Table of contents :

Sports medicine now comprises two main areas: the health benefits of regular physical activity and the health problems associated with sport and physical activity. The first area has become increasingly important now that inactivity and obesity are common. The health problems associated with sport have also assumed increasing importance because of increased participation and professionalism in sport. One of the most important advances in medicine is the documentation that regular physical activity reduces the risk of premature mortality, coronary heart disease, hypertension, colon cancer, obesity, and diabetes mellitus^ref. Recent studies have shown that inactivity and low cardiorespiratory fitness are as important predictors of mortality and morbidity as overweight, obesity, smoking, and raised cholesterol levels and blood pressure^{ref1, ref2, ref3, ref4, ref5, ref6}. Physical activity also protects against breast cancer, and possibly prostate, lung, and endometrial cancer^ref. Substantial health benefits can be obtained by undertaking a moderate amount of physical activity on most, if not all, days of the week^ref. Most recommendations suggest moderately intense exercise with large muscle groupssuch as brisk walkingfor 30 minutes. Recent evidence suggests that exercise sessions may be split into shorter bouts of 5-10 minutes' duration, or even shorter bouts if exercise intensity is high enough.
Recent advances :

• daily, moderately intense exercise such as walking for 30 minutes yields substantial health benefits
• regular physical activity attenuates the health risks associated with overweight and obesity
• strength training in elderly people prevents bone loss with age and improves balance, thus reducing the risk of falls and osteoporotic fractures
• balance training and bracing and taping of the ankle prevent recurrent ankle sprain
• knee injuries may be prevented by balance training and strength and agility training
• balance training may also prevent injuries to the anterior cruciate ligament, which are common among female athletes

• The most important factor in creating a champion are :
• genetic screening : when East African runners began competing internationally, for example, it became apparent that their light frames make them uniquely economical in their use of energy
• in 1968, a Kenyan runner named Kip Keino emerged as a shining star of the Mexico City summer Olympics, setting a world record in the 1500-meter race. Year after year Keino's success has been followed by equally dazzling feats by his compatriots: Kenyan men now hold world records in the 3000-meter track race, the 15-, 20-, and 25-kilometer road races, the half-marathon, and the marathon. Kenyan men have won 13 of the last 14 Boston marathons. Kenyan women are also rising fast: they hold half of the top 10 marathon times and world records in 20-, 25-, and 30-km track races. What is even more remarkable is that most of these athletes come from a small area in Kenya's Rift Valley, from a group of tribes called the Kalenjin who number little more than 3 million people. Altitude is not the key to the riddle, because there's no difference between Kenyans and Scandinavians in their capacity to consume oxygen. And the Kenyan diet is on the low side for essential amino acids and some vitamins as well as fat. The running-to-school hypothesis was demolished as well: Kenyan children aren't any more physically active than their Danish peers. Do Kenyans try harder? The researchers found that the Danes actually pushed themselves harder on a treadmill test, reaching higher maximum heart rates. An important clue is the ability of Kenyans to resist fatigue longer. Lactate, generated by tired, oxygen- deprived muscles, accumulates more slowly in their blood. Comparisons of lactate levels have suggested that Kenyan runners squeeze about 10% more mileage from the same oxygen intake than Europeans can. Compared with Danes, the thinner calves of Kenyans have, on average, 400 grams less flesh in each lower leg. The farther a weight is from the center of gravity, the more energy it takes to move it. 50 grams added to the ankle will increase oxygen consumption by 1%. For the Kenyans, that translates into an 8% energy savings to run a kilometer. Kenyan runners also have a higher concentration of an enzyme in skeletal muscle that spurs high lactate turnover and low lactate production. This results in an "extraordinarily high" capacity for fatty acid oxidation, which helps wring more energy out of the muscles' biochemical reactions. Because intense training alters the body's biochemistry, one can't say for sure whether the ezyme levels are due to genes or training, but experts think it's genetic. Black South Africans, whose running strengths are similar to those of Kenyans, have similar V_O2 max values with white runners--that is, when putting out maximum effort, they used up the same amount of oxygen per kilogram of body weight per minute. But the black runners were more efficient in their oxygen consumption, lasting on a treadmill at maximum speed for twice as long as the whites. As with the Kenyans, the black South African runners accumulated less lactate and had higher levels of key muscle enzymes. Whereas East Africans dominate long- distance running, West Africans have surged to the fore in short-distance events : athletes of primarily West African descent--which includes the majority of U.S. blacks (e.g. Carl Lewis)--hold all but 6 of the 500 best times in the 100-meter race. Various studies have shown that West African athletes have denser bones, less body fat, narrower hips, thicker thighs, longer legs, and lighter calves than whites. But the differences between East and West Africans are even more striking. The fabled Kenyan runners are small, thin, and tend to weigh between 50 and 60 kilograms, whereas West African athletes are taller and a good 30 kilograms heavier. West Africans averaged significantly more fast-twitch muscle fibers--67.5%--than the French Canadians, who averaged 59%. Endurance runners have up to 90% or more slow-twitch fibers. 2 enzymes that are markers for oxidative metabolism have higher activity in the West Africans, meaning they could generate more ATP in the absence of oxygen : in West Africa there may be a larger pool of people with elevated levels of what it takes to perform anaerobically at very high power output. Although training can transform superfast-twitch type IIb fibers into the hybrid type IIa, it is unlikely to cause slow- and fast-twitch fibers to exchange identities. There is evidence that, with extremely intensive long-distance training, fast IIa fibers can change to slow type I fibers. So far, however, there is no evidence that slow-twitch fibers can be turned into fast-twitch ones. As an athlete puts on muscle mass through training, new fibers are not created, but existing fibers become bigger. Homozygosity for the less efficient (X) isoform of a-actinin-3 (ACTN3) (a protein found only in fast-twitch muscle fibers) arising from a common stop-codon polymorphism (R577X) is found in 18% of the members of a group of healthy white Caucasians. The absence of a disease phenotype secondary to a-actinin-3 deficiency is likely due to compensation by the homologous protein, a-actinin-2 (ACTN2). However, the high degree of evolutionary conservation of ACTN3 suggests function(s) independent of ACTN2. There is a highly significant associations between ACTN3 genotype and athletic performance. Both male and female elite sprint athletes have significantly higher frequencies of the wild-type 577R allele than do controls (only 6% of a group of sprinters had the 577X SNP). This suggests that the presence of ACTN3 has a beneficial effect on the function of skeletal muscle in generating forceful contractions at high velocity, and provides an evolutionary advantage because of increased sprint performance. There is also a genotype effect in female sprint and endurance athletes, with higher than expected numbers of 577RX heterozygotes among sprint athletes and lower than expected numbers among endurance athletes. The lack of a similar effect in males suggests that the ACTN3 genotype affects athletic performance differently in males and females. Endurance runners have 2 copies of ACTN2 gene, expressed exclusively in "slow-twitch" muscle fibers, and 26% carry the X form of ACTN3 gene^ref. The less active version, or I allele, of the ACE gene is associated with less muscle, less fluid retention, and more relaxed blood vessels--which would enhance oxygen uptake--and appears to be more prevalent in endurance runners : on the contrary the D isoform is associated with sprinters^ref. In < 2 decades, Kenyans came to dominate the top 20 performances in 6 races ranging from 800 meters to the marathon :


Web resources : International Centre for East African Running Science (ICEARS)
• the Australian Institute of Sport and the Royal Prince Alfred Department of Molecular and Clinical Genetics in Sydney will use muscle and heart performance gene markers to identify future stars : one of the reasons we are identifying the important genes is to get better training programs or maybe redirect athletes to particular sports they may be more likely to be successful in
• long-distance running was crucial in creating our current upright body form : our early ancestors were good endurance runners, and that their habit has left its evolutionary mark on our bodies, from our leg joints right up to our heads. Early humans may have taken up running around 2 million years ago, after our ancestors began standing upright on the African savannah. As a result, evolution would have favoured certain body characteristics, such as wide, sturdy knee-joints. The theory may explain why, thousands of years later, so many people are able to cover the full 42 km of a marathon and it may provide an answer to the question of why other primates do not share this ability. Our poor sprinting prowess has given rise to the idea that our bodies are adapted for walking, not running. Even the fastest sprinters reach speeds of only about 10 m/s, compared with the 30 m/s of a cheetah. But over longer distances our performance is much more respectable: horses galloping long distances average about 6 m/s, which is slower than a top-class human runner. Our savannah ancestors would have been in competition with hyenas, who are also good long-distance runners, to get to the site of a big kill and pick over the remains : you could see a flock of vultures on the horizon and just take off towards them. Or perhaps early humans used their endurance simply to chase prey to exhaustion. Not only do we have springy Achilles tendons and stout leg-joints, our hairlessness and tendency to sweat make us very good at dissipating heat. Running requires a lot of delicate coordination: your legs are off the ground and you need to coordinate your eyes to see where your foot will land^ref. Semicircular canals are unusually large in both modern humans and our evolutionary cousin Homo erectus and this shows that they might have helped primitive runners stay on their feet. In fact, running seems to be the only reason that we have prominent buttocks : when humans walk their gluteus maximus muscles barely fire up, but when they run it goes like billy-o. If the theory is correct, it means that the genus Homo is unique among primates in its running ability. But some experts maintain that there is nothing special about human locomotion, and what separates us from other apes is simply our outsized brains.
• When it comes to athletics, going the distance is not just a matter of fitness. Researchers have found that there is an ideal body mass for running at a certain speed, and for a certain distance. It's common sense that long-distance runners are more lithe than sprinters, but sports scientists have never before managed to work out how or why weight relates to event distance. Weyand and Davis argue against the idea that most of the energy needed for running goes into the effort required to move and accelerate your limbs. This is an important and somewhat controversial issue : during steady-speed running on level ground, the body has mechanical tricks that allow the energy required for swinging and bouncing the limbs to be recycled from stride to stride. That means our elastic tendons do most of the work, letting us bounce along once we are up to speed without requiring much extra energy. Perhaps 90% of work put into our limbs is conserved this way, Weyand estimates. Instead, most of our energy is spent pounding the pavement and supporting the weight of the body. There are no tricks for avoiding gravity. The faster you go, the more energy is spent hitting the ground. To find the relationship between running speed and the force needed to support the body, the researchers tested volunteers on a treadmill. At their personal top speeds both men and women were hitting the ground with a force of around 2.5 times their own body weight. At lower speeds, they exerted less force^ref. If running fast requires a more forceful step, the researchers thought, then you need more muscle, tendon and sinew to support those speeds. But being too heavy would slow you down, because it takes energy to carry weight around. This led them to believe that there might be an ideal body mass for a given speed. The researchers looked at records of élite athletes from a variety of running events, each of which suits itself to a different speed. By collecting the heights and weights of the world's 45 fastest men and women over eight different track distances for the past 14 years, they uncovered a surprisingly simple relationship between event distance and a runner's body size. If you are of a similarly athletic frame, you can find where you lie on this curve, and what your ideal running distance is. Now look up your BMI on this graph, and read downwards from that point to find your ideal running distance. Note this is different for men and women. The graph was compiled using data from athletes, who can attribute more of their weight to muscle than the average person.


Investigation into the force runners exert on the ground might explain this curve, with more muscular runners pounding the ground hard for short sprints and skinny runners having a more gentle step over the long haul. The research also contributes to ongoing debate about the running ability of large animals, including dinosaurs. Based on observations of skinny long-distance runners and the lumbering elephant, scientists have previously concluded that heaviness of any kind is bad for track times. In 2002, scientists hit the headlines by suggesting that, at 6,000 kg, Tyrannosaurus rex would have been unable to manage more than a brisk walk^ref. It may be time for a rethink about the running abilities of larger animals. Without sufficient musculoskeletal mass, faster running speeds cannot be attained. Having to carry extra mass is not always a performance detriment.
• training :
• Roger Bannister, who in 1954 became the first person to run a mile in under 4 minutes - trained for only 35 minutes a day. That's barely considered a warm up today, when the mile record stands at 3 minutes 43.3 seconds.
• video feedback can hep athletes focus their more traditional training in events such as high-jump and diving
• electromyography (EMG) : the muscle groups coaches had been focusing on for the Maltese cross - a challenging move on the rings where a gymnast holds his body up in a horizontal position - were not the ones that the gymnast was actually using for the trick
• many athletes report that training at high altitude helps to boost endurance. The low-oxygen environment stimulates the body to produce more RBCs, meaning that more O₂ is delivered to muscles. But the thin air at high altitude makes exercise hard work, so any gains are likely to be offset by the added physical stress, especially in the case of sprinters who operate in short, explosive bursts. Trainers are increasingly recommending the "live high, train low" phylosophy for endurance athletes. Training at sea levels allows such athletes to exercise hard, while benefiting from the raised RBC count triggered by their high-altitude lifestyle. Some studies have shown an increase in the level of haemoglobin found in RBCs^ref, whereas other have found no change in blood markers at all^ref. If one could look at all the genes that are induced by low oxygen levels in a big enough pool of athletes, one would learn how to predict which ones would benefit from altitude training. Eero Mantyranta, the 1964 Finnish cross-country skiing gold medallist, for example, had a mutation in gene encoding for EPO, which sports scientists believe accounted for his extraordinary stamina. What science can bring to the athlete is perhaps 0.1% : 99.9% is still down to athletes themselves.

Web resources : Colorado Altitude Training
• technique : Mont Hubbard's Sports Biomechanics Laboratory on the Davis campus has studied, among other things, the mechanics of the high jump and the pole vault, the aerodynamics of the discus and the shot put, the flight of punted footballs, the bend of curveballs, the flexing of fishing rods and racehorse forelimbs, the swiveling of skateboards, and the rolling of basketballs around rims. In the 1980s, he developed a system to help javelin throwers launch their spears at just the right angles. In the '90s, he built a bobsled simulator for U.S. Olympians. Currently, Hubbard and his group are analyzing ski jumping, women's gymnastics, trampoline, bungee jumping, and Frisbee flight. In November 2003, Mont Hubbard and colleagues argued in the American Journal of Physics that a well-hit curveball would sail farther than a perfectly struck fastball--even though the curveball moves slower and packs less energy, both before and after it's walloped. That's because a batted ball travels farther if it has more backspin to give it aerodynamic lift. The top-spinning curveball approaches the batter already turning in a direction that increases the backspin of the batted ball. On the other hand, the back-spinning fastball comes at the batter spinning the wrong way, which decreases the backspin of the outgoing orb. As a result, an optimally struck curveball will travel around 455 feet (138 meters), about 12 feet (3.5 meters) farther than a well-hit fastball. But Robert Adair, a physicist at Yale University and author of The Physics of Baseball, contends that Hubbard and colleagues must have overestimated the lifting effect of spin. Such ruminations also underscore the appeal of muscle-building anabolic steroids : once an athlete has perfected a technique, the only way to throw farther is to boost strength and arm speed--for some, a pursuit that knows no bounds.
• state-of-the-art technology can be essential, particularly in sports that rely on specialized equipment, such as tennis or pole vaulting
• when the International Olympic Committee declared at the last minute that "sharkskin" swimsuits were legal for the 2000 games in Sydney, Australia, swimmers had just 1 day to decide whether to ditch their tried-and-true swimwear for the flashy new ridged bodysuits that could potentially shave seconds off their times. In a traditionally low-tech sport, choice of equipment suddenly took on make-or-break significance. For some of the world's best swimmers 4 years later, the choice is no longer theirs. Stars such as Michael Phelps, Inge de Bruijn, Lindsay Benko, and Grant Hackett are obligated to wear Fastskin, a swimsuit made by Speedo, their sponsor. The companies TYR and Arena also have swimmers wearing their versions of the suit, inspired by sharkskin and intended to cut down on drag, the friction that slows any body moving through water. On its Web site, Speedo states that Fastskin reduces drag up to 4%. Other companies make similar claims. Sharkskin is textured with ridges, known as "riblets," that reduce the amount of skin surface area that comes in contact with water. That allows sharks to glide through water with much less friction than one would expect. In 1987, the hull of an America's Cup sailboat was textured to mimic the skin of pelagic sharks; it won the race and was so fast that the texturing was outlawed. The advantage made sense: Pelagic sharks cruise long distances at speeds approaching those of sailboats, around 15 knots, or 28 kilometers per hour, so the benefit from the riblets was transferred from beast to boat. The suits are designed to lower two types of drag: skin friction and pressure drag. The trick for reducing skin friction is making the riblets just the right size. If they are too big or too small, water floods the valleys, creating more surface area than a standard suit has. Pressure drag, meanwhile, occurs when water flowing over irregular shapes, such as eyebrows, chins, and breasts, peels off in sheets, creating suction. Imagine water flowing over a beach ball until it reaches a critical angle and falls away, creating a vacuum that sucks at the ball. To reduce this effect, the Speedo suit is dimpled, like a golf ball, in strategic places. The indentations set up miniature eddies; turbulent water is more likely to stick to the swimmer than is smooth-flowing water. The suits are designed to keep "sticky" water continuously flowing over the body, thus reducing pressure drag. Speedo's models are based on body scans of 2 Olympic medalists, a man and a woman (Speedo will not reveal their names), in a streamlined diving position. Mannequins of the swimmers match the model's calculated drag predictions to within a few percent, Bixler says. However, neither the mannequins nor the computer-generated swimmers, the basis for calculations of passive drag, stroke or kick the way a human would. We know that if passive drag is less, active drag will also be less. By Speedo's calculations, the bodysuits reduce passive drag 4% in men and 3% in women, whose hips and breasts tend to increase pressure drag. The biggest thing with these suits is the mental aspect. The suit supposedly makes you swim faster, so when you're wearing them--you swim faster
• specially designed rubber track surfaces absorb the impact of each footfall, reducing the wear and tear on runners' joints. Not only will hard surfaces harm runners in the long term, but jarred joints interrupt the smooth flow of runners' strides, slowing them down. Mondo Track, the brand used by the Olympics, is made of natural vulcanized rubber and has a waffle-iron texture on the inside that deforms when stepped on. But it's not too soft, lets the runners' feet sink as if they were running on sand. The track is textured to give traction and avoid skids and spills^ref
• chance also plays a part: cool temperatures or wind might add that extra push for a runner or long jumper
• psychology is vital. Athletes need enormous focus and drive to win. Many people think that the main barrier to breaking the four-minute mile was a psychological one: once Roger Bannister did it in 1954, several others clocked sub-4-minute times shortly afterwards. Sometimes breaking a record involves taking a risk in an event, such as breaking from the pack with a full lap to go, and that takes a certain mindset.
• the discovery comes from an analysis of combat events in 2004 Olympic Games in Athens. In 4 of these events (boxing, tae kwon do, Greco-Roman wrestling and freestyle wrestling) combatants are randomly assigned either blue or red outfits. Those wearing red won 55% of all competitions. In bouts deemed to be evenly matched, the bearers of red did even better, winning > 60% of the time. The reasons for this red advantage are unclear. A red face is commonly associated with anger and aggression, so a bright red shirt or headgear may intimidate an opponent. Alternatively, red clothes could actually boost the wearer's testosterone levels : maybe you get a surge when you pull on that red shirt. Elsewhere in the animal kingdom, red coloration is a marker of high testosterone and superior physical fitness. This has led to some strange effects in studies of animal behaviour : some male birds given brightly-coloured leg bands for identification in long-term experiments have found themselves catapulted to the top of the mating ranks. In human societies, red's aggressive, winning quality may explain why many military uniforms and medals feature the colour. But colour choice can also have a cultural basis. Red might not be the top colour around the world. If you have faith that purple is an imperial colour, then you will be happy wearing purple. Red makes teams perform better. They looked at Euro 2004 soccer tournament in Portugal, and in particular at the 5 teams that wore 2 different colours, one of them red, in different games during the competition. Those teams tended to perform better when wearing red as opposed to their other colours. Of course, a red kit is no full substitute for talent. After all, the perennially successful Brazilian national team wears yellow. But elsewhere the correlation seems to be borne out: England's 2 most historically successful clubs, Manchester United and Liverpool, both have red in their uniforms^ref. Another data set from the 2004 Olympics showed that similar winning biases occur in contests in which neither contestant wears red, indicating that a different mechanism may be responsible for these effects^ref.

Personality color test
When statisticians plot how the best performance in a given event changes over time, they see the graph levelling off. And the shorter the event, the smaller are the slivers of time being shaved off. So although Paula Radcliffe has sliced whole seconds off the marathon world record, sprinters are improving by mere hundredths of a second. Perhaps the only way we can recognize the ultimate performance will be retrospectively, after a record has stood for years. Taking the highest value for each crucial physiological factor ever recorded in an athlete, such as the maximum oxygen uptake, the greatest efficiency with which energy is burned and the best stamina. we may one day see a sub-2-hour marathon or even a three-and-a-half-minute mile, but the probability of finding someone with these exceptional abilities is pretty low. Not every sport can be accurately measured, of course. Running and jumping can be quantified with stick or stopwatch, but football and tennis performances are much harder to gauge. As records become harder and harder to break, we may start comparing athletes by other standards, such as the number of gold medals or their performance over time. Lance Armstrong's 6 consecutive wins in the Tour de France, for example, may never be surpassed. Athletes might also invent new sports to test themselves. The emergence of the triathlon in the 1970s was fuelled by runners, swimmers and cyclists looking for a new challenge; it made its début as an Olympic event in 2000.
Women's times in 100-metre Olympic games have been improving steadily faster than men's since 1900. If this trend continues, a woman should be the fastest person in the world 152 years from now, give or take an ample statistical margin of 724 years. Women would triumph in a time of 8.079 seconds compared to men's 8.098^ref. As they were about the previous prediction, sports scientists are sceptical about this one. The reason women's performance has been improving faster is because women have had growing opportunities to participate in sport and train at a competitive level. But this faster pace of advancement will level out before women's times overtake the men's. The conventional view is that there are basic differences between male and female physiology that mean men will always maintain around a 10% advantage in strength and endurance sports. Because the new analysis ignores this, it is flawed at a fundamental level. The gap between the sexes appears to have plateaued, with women performing at about 90% of male levels. We are approaching the limits of human performance in a lot of the one-dimensional events like the 100-meter sprint or marathon : records will continue to be broken, but the price is extremely high. And the percentage of the population that has the genetic potential to excel at this level is infinitesimal. Apart from the marathon, world records for women have been absolutely static for more than a decade. That plateau wasn't evident 12 years ago. In a letter to Nature published on 2 January 1992, titled, provocatively, "Will women soon outrun men?," Brian L. Whipp and Susan Ward of the University of California, Los Angeles, looked at the world records of five standard Olympic running events, from the 200-meter dash to the 26-mile (42-kilometer) marathon, from the 1920s through 1990. They found that women were improving their times at double the rate of men in the short distances and were narrowing the gap even faster in the marathon, in which record-keeping for women only started in 1955. "The gap is progressively closing," the authors wrote. At that rate, they projected that marathon times could converge by 1998 (they did not !) and that gender differences in all races could disappear by 2050^ref. If the marathon --which wasn't an Olympic event for women until 1984--were excluded, the mean performance gap for running events increased from 11% in the mid-'80s to 12% in the mid-'90s. Men's world records were broken far more often in the '90s than women's--largely due to the extraordinary performance of East African runners. From the world records in 8 main running events from 100 meters to the marathon, 7 suggest an increasing gender gap. The marathon is the exception: the gap has narrowed from 11.9% to 8.4%, thanks to Paula Radcliffe's new record in the 2003 London Marathon ran in just under 135 minutes, shaving almost 2 minutes off the record she set in 2002. The current average gap is now 11.01%, up from 10.4% in 1989. At the highest levels of performance, the gender gap in running performance has actually widened over the last 20 years. Much of the female record is clouded by drug use, especially the records set in the 1970s and '80s by Eastern European women that have never been bested. In 1984, 38 women, mostly from the East Bloc, ran 1500 meters in under 4.05 minutes. In 1991, only 9 did. Although the impressive gains in female marathon performance have suggested to some observers that women have greater endurance than men that's not so: women had not developed long distance; that's why the improvement is much greater on the marathon. We don't see any higher oxidative capacity in women. A smaller body frame gives women an edge on endurance but men can run 10% faster even when the difference in body size is controlled for. The typical young man has a maximum oxygen use capacity, or V_O2 max, of about 3.5 liters per minute, compared with 2 liters for a woman. Although individual levels of testosterone vary widely, males tend to have at least 10 times as much of the stuff as women. The hormone stimulates the creation of red blood cells, which means that men's blood holds about 10% more of the oxygen-carrying protein hemoglobin. Further, the performance of male and female athletes on an exercise bicycle after scientists had withdrawn blood, leaving the subjects with equal amounts of hemoglobin in circulation, has a reduced but not eliminated sex difference in V_O2 max^ref, indicating that other factors, particularly musculature, play into the difference. Men have more muscle and larger hearts in relation to body size and this affects aerobic capacity: a trained woman's heart can pump out the same volume of blood as a man's can, but it has to work much harder to do so. Because testosterone spurs growth of muscle tissue, it also affects anaerobic capacity--the ability to produce energy quickly without oxygen--which gives males an edge in sprinting as well. And female reproductive hormones mean that women, including super-lean athletes, tend to carry around more fat for their body weight than men, and this slows them down : men carrying weights that mimicked the body-fat ratio of women put them on a treadmill lose gender gap in performance. Indeed, athletics experts rack their brains to think of any sport in which women's physical characteristics might allow them to outstrip their male counterparts : swimming the English Channel might be one event because fat is so crucial for keeping warm. As for the gender gap in running, I defer to Norway's marathon queen Grete Waitz, setter of world records in the 1970s and '80s, who said: "As long as women are women, I don't think they will surpass men."
• environmental conditions : during the 1984 Olympics in Los Angeles, British runner Steve Ovett collapsed after the 800-metres final with severe respiratory problems and had to spend 2 nights in hospital : pollution (O₃ levels hit highs of 500 mg/m³) was one of the major factors in his exercise-induced bronchoconstriction (EIB). 2 pollutants of particular concern to athletes are ozone and particulates — tiny bits of soot and other matter — both of which can irritate the lungs and cause asthmatic symptoms. In Athens, many August days are characterized by a brownish–yellow smog of photochemical pollutants, which the locals call 'nefos'. When the nefos hangs, ozone levels can rise to > 160 mg/m³, some 40 mg/m³ higher than the WHO's recommended limit. At the same time, particulate concentrations can hit 50–60 mg/m³ — just above the 40–50 mg/m³ limit set by the European Commission. Some 7% of the general population suffer from asthma. Heavy exercise can exacerbate the problem and about 13% of normal people and 20% of athletes report asthma-like symptoms as a result. This figure shoots up to 50% for road cyclists, who tend to breathe heavily during their endurance event. The list of afflicted athletes includes Paula Radcliffe, who holds the world record for the women's marathon, and cyclist Jan Ullrich, who won the Tour de France in 1997 and a gold medal at the Sydney Olympics in 2000. The extent to which athletes are likely to be affected by pollution depends to some degree on their event. Endurance and outdoor athletes are more at risk than, say, table-tennis players. In Athens, road cyclists and marathon runners are likely to be most affected, because the races will take them close to the Parthenon and the Acropolis — one of the most polluted districts of the city. Athletes can cycle about 150 litres of air in and out of their lungs every minute during competition — ten times more than normal — which exposes them to more pollution. To make matters worse, they also inhale much more deeply, taking pollutants into the deepest regions of the lungs. Even spectators who are exposed to these pollutants are easily taken up to the threshold level, but it is the athletes who are at greatest health risk. The performance of highly trained athletes exposed to ozone concentrations of 100 mg/m³ — over half the level expected for a hot and calm August day in Athens, decrease by about 3–4%. The US Olympic Committee took some of its athletes to Athens to see how they would perform : about 20% of the team members are known asthmatics, or are known to suffer from exercise-induced asthma. But a further 30% of the non-asthmatic athletes were sensitive to Athens' air-pollution levels. The difference was subtle, but for these athletes, the pollution made breathing just a little harder. Athletes can then be treated with anti-asthmatic drugs : b₂-agonists are on the Olympic banned list and are available only to proven asthmatics. But other sensitive athletes can take alternative anti-inflammatory medication, including leukotriene antagonists — a new class of anti-asthmatic drug that blocks receptors in the lungs that normally trigger inflammation — or antioxidizing agents such as vitamins C and E. They might not be as effective as b₂-agonists, but at least they are legal. Athens could win gold for the hottest games ever held — a dubious honour currently held by St Louis, the 1904 Olympic host, where the average daily maximum temperature in summer was 31 °C. At those games, only 14 of the 34 starters finished the marathon. the United States has also sent its athletes to islands such as Mallorca and Crete to try to acclimatize them to the Mediterranean climate. Acclimatization to such conditions seems to prevent heat injury. But even with the best preparation, athletes will lose fluid more quickly and will be more prone to collapse. The 2008 summer games in Beijing will likewise be a challenge for athletes. The annual average particulate concentration there is as high as 162 mg/m³ — about 3 times that in Athens — and temperatures are similar to those in the Greek capital. Predictions for Athens in August 2004 : O₃-level high : 160 mg/m³; particulate-level high : 50-60 mg/m³ ; average daily temperature high : 33°C ; humidity : 49%
• contraindications to agonistic sports
• hypertrophic cardiomyopathy (HCM) : Domenico Fioravanti won 2 gold medals at the Sydney Olympics in 2000 — for the men's 100-metre and 200-metre breaststroke. In January, the 27-year-old Italian swimmer was diagnosed with HCM and, under Italian law, he was forced to retire from competitive sport. Fioravanti suffers from the same genetic problem that killed Cameroonian footballer Marc-Vivien Foé in June 2003 while he was playing in the Confederations Cup semi-final against Colombia, followed 7 months later by Hungarian Miklos Feher, who died while playing for Portuguese football team Benfica. Both men died on the pitch — suddenly, and in front of the cameras. Even though Fioravanti knows he has the same condition and is well aware of the risks, his family is campaigning for a relaxation of the Italian law. They want him to keep on swimming — or at least to have the option. In Italy, uniquely, athletes are required by law to get an annual fitness certificate before being allowed to take part in any competitive event. As part of this assessment they are given an electrocardiogram (ECG) and questioned about their family history. If there is a suspicion of disease, they go on to have an echocardiogram which provides information about muscle thickness and the size of the heart's chambers. If this shows an abnormality, the athlete is automatically disqualified — unless the sport is considered low risk, such as snooker or archery. If an athlete sneaks through the system and goes on to die while playing, the doctor who signed the authorizing certificate can be held liable if found negligent. The Italian system seems to prevent instances of sudden death among athletes : of some 34,000 hopeful athletes screened for the condition between 1979 and 1996, 22 had HCM and were disqualified from competitive sport. Only one athlete, who slipped through the tests, subsequently died of HCM^ref. Screening is less efficient at detecting another potentially lethal heart abnormality called arrhythmogenic right ventricular cardiomyopathy (ARVD). Diagnosis of HCM is often not clear-cut, partly because exercise causes non-harmful changes to an athlete's heart muscle that can be mistaken for a sign of HCM. Some of this confusion might be avoided if a genetic test existed. Even if a comprehensive test was available, cost would prohibit its use for young athletes. The Seidmans admit that the price tag of US$3,000 means their test may not be feasible for screening the vast population of young athletes. Even ECG and echo tests are currently considered too expensive for many, but it might be worth considering for the considerably smaller population of Olympic athletes. One case frequently discussed by doctors concerned about this issue is that of Nicholas Knapp. A talented 17-year-old basketball player, Knapp had already been offered a sports scholarship at Northwestern University, Illinois, when his heart stopped at the end of a game in 1994. He was resuscitated, diagnosed with HCM and surgically implanted with a defibrillator. Nevertheless, he accepted the sports scholarship. The university allowed him to keep the scholarship, but barred him from playing intercollegiate basketball on medical grounds. A lengthy court battle ensued, in which Knapp argued that the choice was his, even if by playing he risked death. Northwestern's decision was eventually upheld, but Knapp was free to enrol in another university's basketball programme, and did so. 3 years after his first cardiac arrest, he suffered an episode of tachyarrhythmia — an abnormally fast and irregular heartbeat. His defibrillator discharged, probably preventing a second arrest and saving his life. Since Knapp's case, it has been hard for athletes with a known condition to play competitively in the United States. But, 10 years on, there are still no formal laws to govern these decisions, only guidelines. HCM patients had to wait until this June for a guide^ref on participating in recreational sport. The American Heart Association recommends that people avoid 'burst' activities such as sprinting, and rates the advisability of different sports for people with different conditions. Swimming is listed as "probably permitted" for HCM patients — although this is not meant to apply to athletes at the Olympic level. The median age of HCM sufferers who die while engaged in sport is very young — just 17 years old. In the United Kingdom athletes are not routinely checked for HCM. And when a sudden death occurs relatives are rarely informed about the victim's genetic condition or the possible risk to themselves. Fioravanti considered going to live in another country where he could continue to swim, but decided he would suffer too much away from home. So after the closing ceremony of this year's Olympic Games, he will begin building his new career — as a trainer, rather than a swimmer.

Web resources :
• Guidelines on HCM and sport
• Cardiac Risk in the Young
• recovery :
• cold baths : after an event, athletes will submerge themselves in water at about 12çC for up to a minute, jump out for a minute, and repeat the cycle 3-5 times. Australian swimmers report that it cuts the time they have to spend doing warm-down laps by about 25% - they do these laps untile their lactate levels are below a critical level, measured by pinprick blood samples by the side of the pool. One theory about how cold baths work is that repeated constriction and dilation of blood vessels helps to flush out lactate - an acidic byproduct of the body's combustion of sugars that can stop muscles from contracting properly. And, the baths dull pain, givign athletes a psychological edge in subsequent events. The icy baths used by the Autralians may sound alittle extreme, but htey are not as bad as the cryochambers popular with some European nations such as Germany and Poland. For these, athletes don socks, gloves and face masks before braving air at -110°C to -150°C for up to several minutes. Such chambers may or may not work better than ice baths, but they require constant medical supervision. The more casual sports-person may think that heat should be the way to unwind, but saunas and spas are definitely out as they dehydrate the body, th last thing an overworked athlete needs.
• protein-rich sports drinks may help endurance athletes to stay the pace. Long-distance cyclists pedal up to 40% longer when they regularly refuel with a drink fortified with whey protein and carbohydrates, instead of a carb-only beverage. Endurance runners may experience similar positive effects. Protein-rich drinks may also help to reduce the muscle damage that occurs during gruelling exercise. Drinking the beverage during a workout lowers blood levels of CPK (a marker of muscle injury) by 80%^ref.
• capsaicin, the chemicals that makes chili peppers hot, is often used in pain-relieving balms. But the chemical might be doubly useful to endurance athletes - rats who ingested capsaicin show increased swimming stamina. Capsaicin causes the body to break down fatty acids, instead of glycogen, for energy. As fatty acids convert to energy more slowly than glycogen, a runner's energy stores may last longer, prolonging the time before the athlete "hits the wall". Could a fiery meal the night before a race therefore help runners stay the course ?^ref
• doping (endogenous compounds with abnormal entry way or dosing or xenobiotics that increase physical performance(s)). Doping represents a formidable threat to the future of sport, and the recent advances in this area have been political rather than scientific. The political events providing momentum to the antidoping movement started in 1998 when the Tour de France cycle race was hit by the worst drug scandal in its history. In the same year, authorities investigated the Italian Olympic Committee's testing laboratory. These and other high profile stories, together with much negative media exposure, prompted the International Olympic Committee to reconsider its approach to combating doping and led to renewed discussions about the list of banned substances and methods to detect their use^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8, ref9, ref10}. Current regulations call for a minimum 2 year suspension and heavy fines for athletes found guilty of taking steroids and other performance enhancing substances, and the scientific and technical standards and procedures for analyses and equipment have been standardised. In November 1999 the World Anti-Doping Agency (WADA) was established to coordinate testing done outside competitions. However, the WADA is faced with many challenges, including the development of effective testing methods. Taking erythropoietin boosts the body's red blood cell count, improving the blood's ability to transport oxygen to the muscles, and thereby enhancing endurance performance. The potential improvement in performance from using erythropoietin is formidable : maximal oxygen uptake may be increased by more than 10%. Some international sports federations have excluded athletes with packed cell volume or haemoglobin levels above certain limits from participation in competition. However, a substantial improvement in maximal oxygen uptake may be achieved even with normal haemoglobin levels. Although the World Anti-Doping Agency has funded considerable research with promising results, it has still not established efficient testing methods to combat misuse of erythropoietin. The development of more effective methods to detect the misuse of erythropoietin and other hormones is one of the biggest challenges for sports scientists. Sport and physical activity should be part of a healthy lifestyle. Preventing and treating medical problems in active patients is as important as promoting exercise. To do both effectively, primary care doctors need to be educated, and sports medicine must be included in the curriculum at all levels of medical training. Athletes have been seeking an artificial edge since at least the late 1800s, when runners and long-distance bicyclists used nitroglycerin and even cocaine to boost stamina and block pain. But although authorities began testing for banned substances in the 1970s, their efforts had little impact. A series of astounding world-record performances in the 1980s, especially in power sports such as the shot put or hammer throw, were almost certainly fueled by testosterone and other prohibited anabolic steroids. Tucked on the wooded edge of this village in the Saxon hills south of Dresden is a drab, single-story office building with a sinister past. Until 1989 officials of the German Democratic Republic tested their athletes here to certify them as drug-free before international competitions. But it was all a charade. Many of the East German athletes, both men and women, were systematically doped up with testosterone and other anabolic steroids, often without their knowledge. It was the Kreischa lab's responsibility to ensure that the regimen was suspended long enough before a competition to flush out any traces of drugs. Sometimes the drug docs cut it too close : you would hear that a certain famous athlete couldn't travel to a competition because of a 'sudden illness. Drug use helped inflate female performance before the fall of communism :


The competition between testers and abusers is an ongoing cat and mouse game. It might take them only a week or two to develop a new steroid that could not be tested for, but it is much harder to determine whether these chemical tweaks affect the drug's effectiveness. Drug testing was first introduced to the Olympics in 1968 and was used to detect about 20 drugs. The roll-call now numbers more than 150, and is still growing. But the number of illicit substances is probably even larger as we simply don't know how many designer drugs there are out there. Doping labs must then make a judgement about whether the level of a certain body chemical has been artificially elevated. Human beings exhibit a very wide range of body chemistry, and world-class athletes often find themselves at the extremes of that range simply because of a mixture of genetics and training. This has led to a string of appeals against recent bans for alleged nandrolone doping, which damage the credibility of both the athletes and the doping labs. The Atlanta Olympic Games in 1996 marked the first time every specimen was screened by gas chromatography (GC) coupled to high-resolution mass spectrometry (MS). A further improvement may be seen with GC/MS/MS and quadrupole ion traps. Electrospray HPLC/MS has also been applied to the detection and confirmation of peptide hormones in urine. The ability to detect subtle differences in oligosaccharide structure may provide a way to detect abuse of recombinant glycoproteins. Simply decreasing detection limits is not enough; new technology also allows development of a foundation on which to base interpretation. Application of HPLC/MS/MS has allowed direct measurement of steroid conjugates in urine. The relative importance of sulfate, glucuronide, and other conjugates and metabolites of testosterone and epitestosterone can now be assessed. In East Germany athletes were lavishly funded as an international propaganda tool, questioning the value of top-level sports. We are not dealing here with problems of human existence or survival : the world will not come to an end if dopers go uncaught. The motivation is the example that elite athletes set for millions of amateurs: it's important for people to be able to understand that you can do amazing things without doping.
• replacing therapy
• vitamin B₆
• branched chain amino acids
• HCO₃^- : prevents pain perception buffering lactate but may cause diarrhoea.
• L-carnitine and propionylcarnitine increases fatty acid oxidation in myocardium and skeletal muscles and lactic acid clearance, allowing better recovery from efforts (instead the cheaper DL-carnitine lowers L-carnitine concentrations). No side effects.
• creatine occurs naturally in the body. Some is derived from dietary sources, but endogenous synthesis covers individual requirements. Creatine deficiency occurs only in subjects with genetic disorders. Oral creatine supplementation at supraphysiological doses seems to slightly improve the performance of some types of muscle exercise, but only those lasting < 30"; even this small effect is inconsistent. The vague regulatory status of creatine supplements hinders effective monitoring of adverse events. Serious adverse events have been reported in people taking creatine supplements, but it's still unclear whether or not the creatine is responsible. Animal data suggest a link with cancer after long term exposure. The precise composition of creatine supplements is unclear: contamination is possible, and other substances, especially doping agents, are sometimes added. Taking creatine supplements is inadvisable.
• hemotransfusion
• from donors
• autohemotransfusion : 500 mL blood are collected and concentrated and readministered after > 7 weeks, when the hematocrit has returned normal. This allow an hematocrit increase of ~10%, which is annihilated in the following 9 weeks. Autohemotransfusion is considered licit only if practiced within 2-4 weeks, i.e. when it cannot increase final hematocrit.
• splenectomy decreases hemocatheresis and hence increases hematocrit
• banned substances :
• anabolic agents : a group of muscle-building compounds that includes ...
• non-steroidal anabolic agents
• bicalutamide, a commercial drug used to treat cancer of the prostate
• anabolic steroids (AR agonists) [e.g. Marion Jones and Chryste Gaines and world-record sprinter Tim Montgomery]. Although women produce some testosterone naturally, ratcheting up levels even slightly leads to increased body hair and acne and can wreak havoc with the reproductive system. In men, taking steroids suppresses natural production of testosterone, which can lead to bigger breasts, shrunken testicles, and infertility. In both sexes, high doses of the drugs damage the liver and the cardiovascular system. As testing for steroids began to be enforced more strictly in the 1990s, use of the drugs plummeted --and the pace of record-breaking tapered off. The antidoping forces seemed to have the upper hand until 2002, when the sport world was rocked by revelations that a pair of so-called designer steroids--drugs with no legitimate medical use--had been synthesized, apparently to elude doping testers. In one case Catlin's team detected unusually low levels of natural steroids such as testosterone, epitestosterone, and androsterone in the urine of a female cyclist, a sign that something was amiss. Probing further, his group found traces of norbolethone, an androgen developed by Wyeth in the 1960s. In animal tests, Catlin says, norbolethone appeared to be a very effective muscle builder while having relatively few masculinizing side effects. It was tested in short children and underweight patients, but Wyeth shelved the compound, apparently because of toxic side effects. Evidently, someone was cooking up a new supply. A whistleblower made the second discovery possible. In June 2003 Catlin received the residue from a used but empty syringe from the U.S. Anti-Doping Agency. A track coach had sent it to the authorities, suggesting that they take a careful look. Within a few weeks, Catlin and his colleagues had identified tetrahydrogestrinone (THG). The new chemical, which had never before been described, resembles 2 steroids banned for use by professional athletes: gestrinone, prescribed occasionally for the treatment of endometriosis, and trenbolone, which has some uses in veterinary medicine. Both steroids have powerful anabolic effects, and the UCLA team quickly suspected that the derivative had been designed to activate the same receptors while foiling standard screens for known steroids. When authorities tested urine stored from previous competitions, they found at least a dozen THG-tainted samples, many from athletes who had connections to BALCO. Lawyers for athletes who tested positive argued that the authorities couldn't demonstrate that the substance is an anabolic steroid, and therefore it could not be classified as a banned substance. Indeed, the chemical's effects in animals--much less humans--had never been characterized in a legitimate lab; standard animal tests take many months. Under court- imposed time constraints, scientists resorted to a quicker solution, a test originally designed to ferret out environmental pollutants that mimic hormones. The test uses yeast cells altered to make the human version of the testosterone receptor as well as a luminescent protein that glows when the receptor is activated. Using the test, David Handelsman of the ANZAC Research Institute in Concord, Australia, found that THG lights up the cells more brightly than standard anabolic steroids such as trenbolone and even testosterone.
• naturally occurring hormones such as testosterone : hormone levels fluctuate from hour to hour and from person to person, so measuring absolute amounts can't nail a doper. To do that, scientists must find secondary signals indicating that the body's normal chemistry has been tampered with.
• synthetic ones such as
• tetrahydrogestrinone (THG) (it has been linked with high-profile sprinters such as Dwain Chambers in August 2003)
• nandrolone (it has been linked with soccer players) occurs naturally in the body in tiny quantities. Tests actually look for molecules that are produced when the body breaks down this steroid (< 2 ng/mL urine). But traces of the breakdown products from nandrolone are sometimes found in diet supplements that are frequently used by athletes. These traces would be insufficient to affect their performance, but enough to put them over the doping limit.
• xenobiotic norsteroids are xenobiotics with androgenic and anabolic properties known since as far back as the 1930s.
• stanozolol (found in Ben Johnson's urine at the Seoul Olympics in 1988).
Markers : even if mass spectrometer fails to flag unexpected side chains or telltale peaks, it can reveal subtle differences in the ratio of carbon isotopes that can help identify the origin of organic molecules. An unusual ratio of carbon-12 to carbon-13 in certain molecules can raise a red flag in a doping test. If a steroid molecule has a ratio typical of a plant rather than an animal, it is a sign that it comes from an outside source
• xenobiotic norsteroids
• increased [either norandrosterone (19-NA) or noretiocholanolone (19-NE)]_urine > 1-2 ng/mL, which are the main metabolites for nandrolone (NT) and most norsteroids with anabolic properties
• testosterone
• increased [testosterone (T) / epitestosterone (epiT)]_urine (low specificity, e.g. in abnormally low testicular epiT production, probably related to genetic factors)
• increased [testosterone / 17a-hydroxyprogesterone (17-OHP)]_serum^ref
• HCG is manufactured from the urine of pregnant women since it is excreted in un-changed form from the blood via the woman's urine, passing through the kidneys. The commercially available HCG is sold as a dry substance and can be used both in men and women. in women injectable HCG allows for ovulation since it influences the last stages of the development of the ovum, thus stimulating ovulation. In a man HCG stimulates production of androgenic hormones (testosterone). For this reason athletes use injectable HCG to increase the testosterone production. HCG is often used in combination with anabolic/androgenic steroids during or after treatment. Since the body usually needs a certain amount of time to get its testosterone production going again, the athlete, after discontinuing steroid compounds, experiences a difficult transition phase which often goes hand in hand with a considerable loss in both strength and muscle mass. Administering Lepori® HCG directly after steroid treat-ment helps to reduce this condition because HCG increases the testosterone production in the testes very quickly and reliably. In the event of testicular atrophy caused by mega doses and very long periods of usage, HCG also helps to quickly bring the testes back to their original condition (size). Since occasional injections of HCG during steroid intake can avoid a testicular atrophy, many athletes use HCG for 2-3 weeks in the middle of their steroid treatment. It is often observed that during this time the athlete makes his best progress with respect to gains in both strength and muscle mass. Those who are on the juice all year round, who might suffer psychological consequences or who would perhaps risk the breakup of a relationship because of this should consider this drawback when taking HCG in regular in-tervals. A reduced libido and spermatogenesis due to steroids, in most cases, can be successfully cured by treatment with HCG. Most athletes, however, use Lepori®-HCG at the end of a treatment in order to avoid a "crash," that is, to achieve the best possible transition into "natural training." A precondition, however, is that the steroid intake or dosage be reduced slowly and evenly before taking HCG. Although HCG causes a quick and significant increase of the endogenic plasma- testosterone level, unfortunately it is not a perfect remedy to prevent the loss of strength and mass at the end of a steroid treatment. Although Lepori®-HCG does stimulate endogenous testosterone production, it does not help in re-establishing the normal hypothalamic/pituitary testicular axis. The hypothalamus and pituitary are still in a refractory state after prolonged steroid usage, and remain this way while HCG is being used, because the endogenous testosterone produced as a result of the exogenous HCG represses the endogenous LH production. Once the HCG is discontinued, the athlete must still go through a readjustment period. This is merely delayed by the HCG use. For this reason experienced athletes often take Clomid and Clenbuterol following Lepori® HCG intake or they immediately begin another steroid treatment. Some take HCG merely to get off the "steroids" for at least 2-3 weeks. Lepori® HCG package insert states clearly that HCG has no known effect of fat mobilization, appetite or sense of hunger, or body fat distribution." It further states, HCG has not been demonstrated to be effective adjunctive therapy in the treatment of obesity, it does not increase fat losses beyond that resulting from caloric restriction. 5000 I.U. of HCG in a single injection resulted in elevated testosterone levels for six days after the injection. At a dosage of 1500 I.U. the pharmatestosterone level increases by 250-300% (2.5-3fold) com-pared to the initial value. The athlete should inject one HCG ampule every 5 days. Since the testosterone level remains considerably elevated for several days, it is unnecessary to inject HCG more than once every 5 days. The effective dosage for athletes is usually 1500-5000 I.U. per injection and should-as al-ready mentioned-be injected every 5 days. HCG should only be taken for a few weeks. If HCG is taken by male athletes over many weeks and in high dosages, it is possible that the testes will respond poorly to a later HCG intake and a release of the body's own LH. This could result in a permanent inadequate gonadal function. Lepori® HCG can in part cause side effects similar to those of injectable testosterone. A higher testosterone production also goes hand in hand with an elevated estrogen level which could result in gynecomastia. This could manifest itself in a temporary growth of breasts or reinforce already existing breast growth in men. Farsighted athletes thus combine HCG with an antiestrogen. Male athletes also report more frequent erections and an increased sexual desire. In high doses it can cause acne vulgaris and the storing of minerals and water. The last point must especially be observed since the water retention which is possible through the use of HCG could give the muscle system a puffy and watery appear-ance. Athletes who have already increased their endogenous test-osterone level by taking Clomid and intend subsequently to take HCG could experience considerable water retention and distinct feminization symptoms (gynecomastia, tendency toward fat de-posits on the hips). This is due to the fact that high testosterone leads to a high conversion rate to estrogens. In very young athletes Lepori® HCG, like anabolic steroids, can cause an early stunting of growth since it prematurely closes the epiphysial growth plates. Mood swings and high blood pressure can also be attributed to the intake of Lepori® HCG. HCG's form of administration is also unusual. The substance choriongonadotropin is a white powdery freeze-dried substance which is usually used as a compress. Each package, for each Lepori® HCG ampule, includes another ampule with an injection solution containing isotonic sodium chloride. This liq-uid, after both ampules have been opened in a sterile manner, is injected into the Lepori® HCGampule and mixed with the dried substance. The solution is then ready for use and should be injected intra-muscularly. If only part of the substance is injected the residual solution should be stored in the refrigerator. It is not necessary to store the unmixed HCG in the refrigerator; however, it should be kept out of light and below a temperature of 25°C. HCG is a relatively expensive compound.
• psychostimulants
• amphetamines
• cocaine
• ephedrine, which is found in some decongestant products
• in January 2004, the World Anti-Doping Agency removed caffeine from its prohibited list of stimulants.
• narcotics : pain-killing drugs, mostly opiates such as morphine, heroin and methadone; the chemically similar codeine is allowed, however.
• diuretics can help boxers or weightlifters to lose weight very quickly, allowing them to compete in a different weight class within their sport. They can also conceal the presence of other drugs in urine.
• peptides and hormones are difficult to detect as they are part of the body's natural chemistry
• recombinant human erythropoietin (Epo) (r-HuEPO) (banned by the International Olympic Committee in 1990) increases the maximum anaerobic power (V_O2max, whose upper limit anyway depends on ventilation, carrying and diffusion rates) but the increased blood viscosity increases likelihood of irreversible arterial hypertension, heart failure and thromboses (=> AMI and stroke). It became available in the late 1980s in Europe and is thought to have played a role in the deaths of more than a dozen Dutch and Belgian cyclists who died of sudden heart attacks in the 1980s [e.g. the world champion sprinter Kelli White in June 2004]. The detection of r-HuEPO abuse by athletes remains problematic. Because the blood test does not measure illegal r-HuEPO directly, it cannot prove a doping allegation. A new analytical procedure was developed by Lasne and de Ceaurriz in June 2000 (just before Sidney's Olympic Games) for detecting r-HuEPO in urine and was applied to specimens from cyclists participating in the the infamous Tour de France 1998 competition, which was sullied by scandals about EPO doping. Just in time for the 2000 Olympic Games in Sydney, Australia, the IOC introduced the new combined blood and urine test for EPO (the so-called “Australian method”). Owing to microheterogeneity in their structures, natural and recombinant EPO comprise several isoforms, some of which have charge differences and can be separated by isoelectric focusing. The isoelectric patterns of the 2 recombinant EPO-a and b forms are very similar (both have an isoelectric point, pI, in the range 4.42-5.11); although EPO-a has an extra basic band, both differ from natural, purified urinary EPO, which has more acidic bands (pI 3.92-4.42), probably due to post-translational modifications such as glycosylation, which is species- and tissue-type-dependent. Such differences in the urine analysis allows to ascribe excreted EPO to a natural or recombinant origin. An immunoblotting procedure was developed to obtain a reliable image of EPO patterns in urine. The patterns from control subjects consisted of about 10 bands of pI 3.77-4.70, in accord with the purified natural urinary EPO pattern, whereas those from subjects treated with recombinant EPO contained more basic bands, reflecting the presence of recombinant isoforms, and sometimes acidic bands as well, depending on the presence of endogenous isoforms. The presence of exogenous hormone was always evident: any individual injected with recombinant EPO showed a striking transformation of their initial EPO urine pattern. 102 frozen urine samples from participants in the Tour de France 1998 cycling competition were assayed for EPO by using ELISA : 28 of these samples had EPO levels above the normal range of 0-3.7 IU/l (mean, 0.48 IU/l, n=103; 77 samples were below the minimum detectable concentration of 0.6 IU/l). The 14 samples presenting with the highest concentrations (7-20 IU/l) were analyzed : although characterization of the EPO source does not require such high levels for urine analysis, we selected these samples for isoelectric focusing as they were more likely to contain exogenous hormone; indeed, they all gave rise to a banding pattern typical of recombinant hormone. This method for detecting recent exposure to recombinant EPO in athletes could be useful for in-competition controls in events of long duration (for example, cyclists have been known to use exogenous EPO continuously for 6 months at a time), but should find its principal application in out-of-competition testing^ref. 5 indirect markers of altered erythropoiesis (hematocrit (Hct), reticulocyte hematocrit (RetHct), percent macrocytes (%Macro), serum erythropoietin (EPO) and soluble transferrin receptor (sTfr)) are reliable evidence of current or recently discontinued r-HuEPO use^{ref1, ref2}. This test cannot find exogenous EPO if administered 48 hours before the test. Second-generation tests were developed by the Australian Institute of Sport in 2003^ref. The concentration of EPO in urine is fairly low, however, so the test could be foiled if an athlete takes diuretics or other urine-increasing drugs. Analyses performed on the site with a transportable analyser are good and could enable the federations to perform a urinary test to detect rhEPO abuse right after the blood analysis. This time saving is essential to fight efficiently recombinant erythropoietin doping, because the half life of the hormone is very short^ref. A new 2-dimensional electrophoresis (2DE) method for the detection of recombinant erythropoietin (rHuEPO) in urine and its separation from endogenous erythropoietin (HuEPO) involves a one-step acetonitrile precipitation of the proteins in urine, addition of an internal standard, two-dimensional gel electrophoresis (2D PAGE), a single Western blot and chemiluminescent immunodetection. The 2DE method separates HuEPO and rHuEPO isoforms by both iso-electric point and molecular mass. Several urinary proteins have been identified with which the monoclonal EPO antibody used in the current test has non-specific binding. The iso-electric points of these cross-reactive proteins overlap with HuEPO and rHuEPO however, they separate distinctly by the 2DE method. a₂-HS-glycoprotein (HSGP) was identified by peptide mass fingerprinting as one of the urinary cross-reacting proteins, and commercially available purified HSGP was chosen to be added into urine samples as an internal standard prior to separation. Software (EpIQ) was specifically developed that applies four separate criteria to the detection of the migration of rHuEPO and HuEPO relative to the internal standard. The combination of sample preparation, 2D separation, internal standard, standardized blotting procedures and image analysis software enables the 2DE test for rHuEPO in urine to be performed reproducibly and accurately^ref.
• growth hormone (GH) : strengthens bone, cartilage and tendons, but also causes a decrease of fatty tissue and increase of cartilage and muscular tissue (muscles are less elastic !). Authorities have not yet introduced an official test for the compound. Detecting hGH is even harder than detecting EPO, because it doesn't have telltale sugars to betray artificial versions. But in a lucky break for doping sleuths, the pituitary gland's production of growth hormone is rather messy. The gland makes a mixture of variations of the protein as well as protein fragments. The manufactured version, on the other hand, is much cleaner, consisting chiefly of one of the heavier versions, so when someone shoots up with the recombinant protein, the ratio of the different forms is skewed. Endocrinologist Christian Strasburger of the Charité University Clinics in Berlin and his colleagues at the Medizinische Klinik Innenstadt at the University of Munich have developed an immunoassay that measures the ratio of the two forms. The test seems extremely reliable. Another group led by Sonksen of St. Thomas' Hospital has developed a method to measure the effects of growth hormone on the production of other proteins, including insulin-like growth factor-1 (IGF-1) and collagen. The test is not as clear-cut as that developed by Strasburger and his colleagues, but it can detect the effects of hGH weeks after someone has injected it. The Strasburger method works best 24 to 36 hours after injection. Those who go to the trouble and expense--a month's dose costs more than $2500--may not be getting their money's worth. In the normal person with normal levels of growth hormone, adding extra has not been shown to confer a benefit. Yet at the end of the day, if a 0.01% advantage is the difference between winning and losing, a minuscule boost from growth hormone--even if it's purely psychological--might help an athlete to victory. Tackling this murky question, Ho's group is giving growth hormone to healthy volunteers both to screen for biochemical changes that might be picked up in a doping test and to look for performance- enhancing effects. Whether the benefit is real or not, the hormone is on the list of banned substances, and athletes caught using it will forfeit any medals they receive next month in Athens.
• 'restricted' substances : an athlete will not face a ban if they can prove that the substance was not used to enhance sporting performance
• GR agonists, which are used to treat asthma
• b-blockers, which are sometimes used to treat heart conditions
• b₂-AR agonists
• genetic doping : scientists have treated roughly 3,000 humans suffering from life-threatening illnesses with gene therapy, but few cases have been successful and some have been fatal. Given the risks involved, the first gene doping in the sports world may be in an animal sport like dog racing. Microarrays that measure the expression levels of thousands of genes at once could betray blips that might result from gene doping.
• recombinant human GM-CSF-EPO hybrid protein named MEN 11300 was administered biweekly for a total of 6 weeks to rhesus monkeys induced a strong antibody response which neutralized the in vitro biological activity of human EPO while no antibody response could be detected against human GM-CSF. A severe drop in reticulocyte counts at approximately 2 weeks after initiation of treatment was followed by a dramatic decrease in the number of erythrocytes. No effects were observed on GM-CSF-dependent hematopoietic lineages and the clinical chemistry analyses did not reveal signs of general toxicity. Reticulocyte and erythrocyte counts started to recover 3-4 weeks after discontinuation of treatment in concert with a decline in anti-EPO antibody titres. Nevertheless, cell numbers remained below basal levels up to 50 days after the last MEN 11300 administration^ref. Dose response to a single intramuscular injection of rAAV-Epo in monkeys are achievable, although a threshold inoculum of virus is necessary to produce an effect and the therapeutic window is narrow^ref. The 47-year-old Thomas Springstein, a one-time coach of the German Athletics Association (DLV), faces a stiff jail sentence if found guilty of supplying drugs to minors back in 2003 particularly if the accusations of genetic doping (an e-mail containing references to Repoxygen^®) are confirmed. Springstein has also been accused of giving several injections to one of his female athletes to treat an injury despite not having a viable medical permit. Before the doping scandal came to light Springstein worked with some of Germany's top athletes, including East German track stars Katrin Krabbe and Grit Breuer, who were both suspended for 2 years for using the banned steroid clenbuterol in 1992. Krabbe won the 100m and 200m world titles in 1991 while Breuer, who is Springstein's partner, won the 1990 European title at 400 metres^ref.
• marathon mice : the gene engineered in these mice essentially mimics exercise
• engineered mice with constitutively active PPARd burn fat not sugar and have far more of the muscle fibres that work aerobically, and fewer of those that burn anaerobically : this confers endurance (they ran 5,900 feet before quitting and stayed on the treadmill 1 hour longer than the natural mice, which were able to stay running for 90' and travel 2,950 feet) and prevents the modified mice from becoming obese even when they were kept inactive and fed a high-fat diet^ref. Around 80% of the muscle fibres of marathon runners are aerobic, while in non-athletes the percentage is typically 30-40%. This is probably partly due to genetics and partly due to training.
• PPARa inhibitors increase muscle capacity in mice and stop them gaining weight
• mice that lack HIF-1a are less able to switch to anaerobic activity. The mice are churning out less lactic acid, a by-product of anaerobic metabolism commonly thought to cause fatigue, and are clearing it out of their system faster. Again, this has parallels with long-distance runners, who are thought to turn over lactic acid more quickly. But in this case, the animals' athletic feats came at a high price: after four days of extensive exercise, their performance flagged and their muscles showed signs of damage. This may have been because by-products of aerobic metabolism, such as free radicals, had built up to poisonous levels^ref
• Schwarzenegger mice - as they were dubbed by the press for buff action movie star and now California Gov. Arnold Schwarzenegger - were created by Nadia Rosenthal, a developmental geneticist at the European Molecular Biology Laboratory in Monterotondo, Italy, overexpressing a locally acting isoform of IGF-1  (mIGF-1) in fully differentiated, non-dividing muscle cells. They have twice as much muscle as normal mice, live longer, and can recover from injuries that kill their weaker cousins and they avoid scarring. They build muscle without exercising (but when you do exercise them they look even better), and they seem to defy the aging process. EMX2, a protein that is also increased in the regenerating newt limb, is upregulated^ref. Such a treatment would be difficult to unmask, because the doped-up IGF-1 gene, designed to remain in muscle cells where it is produced, would not be detectable in blood or urine : athletes would understandably be reluctant to give muscle biopsies just before a competition. Genentech manufactured and tested IGF-1 in the 1980s but decided not to market it. Tercica, a company in South San Francisco, California, is sponsoring clinical trials of growth hormone plus IGF-1 in short children who don't respond to treatment with growth hormone alone. Preliminary data suggest that the Tercica version does encourage muscle growth. It seems that the body makes at least 4 forms of IGF-1. Another circulates in the bloodstream and suppresses the production of human growth hormone : when production of this form is increased, mice develop oversized and weak hearts and are prone to cancer.
• a Berlin boy was born with a mutation that turns off the gene for myostatin, which in animals seems to block the activation of muscle stem cells. Mice and cattle that carry myostatin mutations have twice as much muscle as normal animals. At 4-and-a-half years old, the boy had the physique of a mini-bodybuilder and could hold out two 3-kg dumbbells with his arms extended^ref. Some experts are thrilled: They suggest that the mutation could be exploited as a treatment for muscle-wasting diseases.
• sport-associated diseases
• unexplained underperformance syndrome (UPS) / over-training syndrome affects perhaps 1 in 10 athletes Although suffereres usually recover after a period of rest, it can ruin preparation for major events. Rowers seen particularly susceptible : athletes in this sport typically train twice a days, 5 or 6 days a week. Whe major competitions approach, they often push their bodies beyond their normal limits for 1 or 2 intense weeks, regularly covering 20 km on the water a day. This overreaching leaves the athletes exhausted in the short term, but in the long term it usually forces their bodies to adapt to intense exertion, improving race performance. But sometimes the strategy results in UPS : continued infections, incrasing fatigue, sleep and mood disturbances, loss of appetite, slow wound healing and gastrointestinal disturbances. If an athlete's performance does not recover after 2 weeks of relative rest, UPS is usually diagnosed^ref. Gauging the prevalence of the condition is difficult, as athletes don't want competitors to know. Researching the condition is also difficult, as serious athletes aren't willing to give regular blood samples, and it would be unethical to induce full-blown UPS in test subjects. In burns patients, levels of anti-inflammatory cytokines, such as IL-4 and IL-10, go up and, apart from calming inflamamtion, also suppress the ability of immune cells that usually attack pathogens, leaving burns patients more vulnerable to long-lasting infections. After a marathon, IL-10 levels shot up, although IL-4 remains constant. But this is nunlikely to be the whole story, as athletes with UPS often complain of tirednes and aching joints when they are apparently infection-free. Levels of IL-6 can rise 100-fold during a marathon and are partly responsible for feelings of tiredness during a race (as when someone has a cold or flu). Injections of IL-6 into healthy individuals will make them tired within a few hours. Some people are more sensitive to the cytokine than others : chronic fatigue sufferers, for example, will become more tired more quickly, and for longer, than control subjects. Injecting a runner before a race will likewise have tiring effects; an experienced club runner typically has a minute added to their time for a 10-km run^ref. Some suspect that over-reaching itself sensitizes athletes to IL-6, making them more likely to feel worse from natural bursts of the cytokine. An ideal experiment would ask runners wll first do a timed 10-km run after an IL-6 injection. They will then "over-reach" by running an incredible 90 km - more than twice as far as a marathon. After a few weeks of rest, they will have an IL-6 injection and run a second 10-km race. If over-reaching sensitizes them to IL-6, one can predict they will perform particulary poorly in this last test. Experts recommend a minimum 6-hour rest between training sessions, as IL-6 levels are significantly higher among subjects who rest for only 3 hours^ref. Psychological stress is thought to contribute to UPS, although no one knows why.
• physical hemolytic anemia, hematuria, hemoglobinuria, proteinuria, and blood cell casts
• ice hockey

Web resources : Ice hockey at CDC
• gymnastics : when Natalia Yurchenko introduced a new vault at the 1983 World Championships in Budapest, it helped her win a gold medal. The move is fiendishly difficult: Yurchenko would sprint 20 meters, cartwheel, land backward on a springboard, and launch herself into the air. Arching her back, she would reach for a padded apparatus called a horse and then propel herself into the air again, somersault one-and-a-half times, twist, and land facing backward. Following that dizzying lead, gymnasts set out to conquer the Yurchenko vault--and injuries mounted. The vault became notorious in 1988, when 15-year-old Julissa Gómez broke her neck while attempting it at the World Sports Fair in Japan. She was paralyzed, fell into a coma, and later died of complications. Within a year, the U.S. Gymnastics Federation, predecessor of USA Gymnastics, banned the move at levels below Olympic competition. Deaths are rare in gymnastics. That's not the case for injuries. Compared with other kinds of athletics, gymnastics stands out for its singular combination of bone-jarring impacts, intense training, young age, and ever-more-demanding skills. Similar injuries afflict both sexes, but more girls participate and they start training younger. Experts fear that elite teens and preteens, by pushing their bodies to the limits, might be raising their risk of osteoarthritis and other health problems later in life. An elite gymnast trains 25 to 40 hours a week, typically executing more than 250,000 "skills" a year. In the 1970s and '80s, elite gymnasts began competing at younger ages. Although that trend has stabilized, preteens are subjecting their bodies to sprains, fractures, and sometime even deformities of growing bones. In 1996, established routines became worth fewer points, so gymnasts who wanted to outscore the competition had to swing higher into the air, execute more twists and somersaults, and otherwise raise their game. For a few years after that, the U.S. national team had problems with a serious kind of knee injury, a tear of the anterior cruciate ligament. Also raising the risk of injury, equipment has been modified for higher performance. For example, gymnasts can jump higher from new vaulting tables with more spring, allowing more air time for acrobatics. Sports scientists say it is hard to nail down the health risks of competitive gymnastics for children. For starters, there is no reporting system for gymnastics injuries. In the one existing system, run by the National Collegiate Athletic Association, gymnastics usually ranks in the top three sports for injuries, behind football and hockey. But that doesn't shed light on the private clubs that train most gymnasts. Coaches of elite gymnasts often may be too busy to let scientists in for a close look. With fewer than 200 elite gymnasts in the United States, most research is done on less-skilled athletes. These studies back the impression that injuries are common. In a 3-year study of 79 female gymnasts aged 7 to 18, Dennis Caine, a sports-injury epidemiologist at Western Washington University in Bellingham, found that 60 girls suffered a total of 192 sprains, strains, and other injuries. The study also showed that the risk of injury was significantly higher for advanced gymnasts. That makes sense, because as gymnasts get serious, they put in longer hours, work harder, and attempt more difficult routines. Caine and others have shown that the most commonly injured body parts in boys and girls include the lower back, shoulder, and ankle. Wrist pain is especially prevalent. In some cases, the distal end of the forearm bones can be damaged, stunting the radius relative to the ulna. It can be career-ending for some kids, because weight-bearing is too painful. Such nagging injuries can continue to plague gymnasts in college, although he says it's unclear whether they flare up later in life. For girls, another concern is delayed growth and sexual maturation. Elite female gymnasts tend to grow more slowly and go through puberty later than other girls. Some don't think intense training can be blamed; a confounding factor is that larger girls who mature earlier tend to drop out from competition. However, other point to several case and cohort studies that indicate at least a temporary halt in growth of some top-level gymnasts, likely due to intense training and poor nutrition. When the gymnasts lightened their load, or retired, their growth rate accelerated. Many of these issues came to a boil during the 1992 Barcelona Olympics, when European newspapers ran stories about the injuries of young female athletes and the extreme training they had undergone. That spurred a research project that many sports scientists call exceptional in its depth and quality. The Federal Institute for Sport Science in Bonn, Germany, asked Gert-Peter Brüggemann, then director of the Institute for Athletics and Gymnastics at the German Sport University Cologne, to study the effects of high-level performance on gymnasts. His team examined various training regimens, using records from the once top-secret facilities of the former East Germany. Compared with Western gymnasts, the East Germans were put through more frequent repetitions of skill sets and more difficult maneuvers and got less rest. In total, their growing bodies had endure a longer, harder pounding compared with those of West German athletes. Those loads had severe consequences. After reviewing archived x-rays and reexamining 42 women and 26 men who once had been elite gymnasts, Brüggemann's group found a much higher injury rate among the East German team than in 23 West Germans who had competed between 1968 and 1985. Mild deformities and abnormalities of the spine were more than twice as common in the East Germans, Brüggemann and colleague Hartmut Krahl, then of the Alfried Krupp Krankenhaus in Essen, reported in 2000 in Belastungen und Risiken im weiblichen Kunstturnen (Load and Risks in Female Gymnastics). Seeking to prevent such injuries, the group also carried out a 4-year prospective study of 135 young elite gymnasts on German national squads. Working with high-speed video cameras and force-measuring devices in the apparatus and landing mats, they analyzed roughly 100 exercises and measured mechanical loads exerted on the body over time. About half the spinal deformities could be explained by the amount of loading. They also discovered that the severity tended to be worse among those with weaker muscles and connective tissue. Stronger muscles absorb the shock of impacts and bad landings, protecting joints and the spine. Based on those findings, Brüggemann's team devised a healthier training regimen in which girls spent less time learning fancy routines, instead logging more hours in the weight room. Far fewer gymnasts suffered pain or injury during the first 3 years of the strength-training program, they found, with ankle injuries alone falling more than 50%. One beneficiary of the program is Brüggemann's daughter Lisa, who competed in the 1999 and 2001 World Championships and will be heading to Athens on the German team. A similar approach has helped the U.S. national team, which has suffered fewer knee injuries since putting a greater emphasis on strength training in 2000. In her lab, McNitt-Gray takes high-speed video of gymnasts, measures forces and muscle movements, and creates computerized stick models to test the effects of modifying the moves. The gymnasts are outfitted with tiny sensors to track their motions and muscle use. This system can be used to warn trainers if the gymnasts are nearing their limits, McNitt-Gray says. Also on the agenda is improving the equipment. By filming the vault board and spring floor with a high-speed camera, Sands and his colleagues found that it wobbles underfoot before heaving the gymnast up. It looks like the gymnast has landed on a waterbed. That's part of what makes the equipment risky, because gymnasts must cope with boards that often compress unevenly and unpredictably. Boards have improved over the years but are still not good enough. Similarly, the characteristics of the safety mats that gymnasts land on depend on their construction, age, and other factors. Brüggemann and his colleagues have recommended that safety mats be stiffened for better stability during landing. Most competitive gymnasts cannot avoid an occasional injury, but little is known about the long-term damage to their health. Anecdotal evidence suggests that elite gymnasts risk developing osteoarthritis and chronic musculoskeletal pain. The few studies that have tested this hypothesis have yielded conflicting results. Experts insist that gymnastics can be made safer without diminishing its elegance and power. Perhaps the most important message is not to cross the pain threshold. The old adage 'No pain, no gain' is inappropriate when it comes to kids. In the pursuit of Olympic gold, however, that message can easily get lost.

Web resources : Gymnastics at CDC
• forced foot
• athlete's foot / tinea pedis
• (American) football

Web resources : (American) football at CDC
• soccer :
• little leaguer's elbow
• sporadic amyotrophic lateral sclerosis (ALS)
Web resources : Soccer at CDC
• diving :

Web resources : Trampolines at CDC
• baseball :
• baseball pitchers' elbow
Web resources : Baseball and softball at CDC
• golf :
• golfer's elbow
• boxe :
• boxer's traumatic encephalopathy
• tennis :
• lateral epicondylitis / tennis elbow
• tennis wrist
• tennis thumb
• endurance sports
• cycling :
• pudendal nerve entrapment => genitalia numbness (50-91%)
• erectile dysfunction (13-24%)
• raised serum PSA level
• prostatitis
• infertility
• priapism
• penile thrombosis
• hematuria
• torsion of spermatic cord
• perineal nodular induration
• When the seat is too high, it can increase stress on the lower back and hamstrings. If it's too low, problems with the distal quadriceps and anterior knee can occur. If you pedal slowly with high resistance (using the big chain ring and smaller cogs), you can strain your quadriceps or knee. Pedaling fast with low resistance can cause increased pressure on the base of your pelvic region and back. Most experienced cyclists will have a cadence (revolutions per minute) between 90-100. For beginning cyclists, a reasonable and energy-efficient cadency might be between 60-80. For activities, including warm-ups, lasting less than one hour, water is sufficient. If the activity lasts longer than an hour, carbohydrate supplements in the form of sports drinks, carbohydrate bars or gels would be beneficial. Cramping also can be avoided by drinking plenty of fluids during exercise. Sports drinks are a good source of fluids, carbohydrates and salts, and between four to eight ounces should be consumed every 15 to 20 minutes. Most sports drinks have 6 percent to 8 percent carbohydrates, which have been found to cause fewer gastric problems and are ideal for absorption. Chafing and skin irritation - often called "saddle sores" - are a common annoyance for cyclists. But they can be minimized by buying properly fitted seats and wearing cycling shorts with plenty of moisture-absorbing padding in the bottom to help protect skin. Cyclists should remove sweaty clothing as soon as possible after training or racing and shower. In addition, one should wash clothes after every use to prevent irritation or infection of broken skin. One of the most important things for cyclists to learn is how to avoid heat-related problems. It takes approximately two weeks to acclimate to heat, longer for extreme heat. If preparing to ride in high heat for a prolonged period of time, a cyclist should build up slowly, by initially limiting workouts to one hour or less, train during the cooler parts of the day and always hydrate. The athlete can then increase training load. In hot temperatures, take a drink every 10 to 15 minutes, even if not thirsty.
• mountain bike
• spinal cord injuries (SCI) (Apsingi S., Dussa C.U.& Soni B.M. . American Journal of Sports Medicine, 34. 1-3)
Endurance athletes have long been warned about getting dehydrated, and many tend to drink more on race day than they do during training. Runners, hikers, bikers, even soldiers on long maneuvers risk dilutional hyponatremia. Hyponatremia occurs in a substantial fraction of nonelite marathon runners and can be severe. In participants to the 2002 Boston Marathon considerable weight gain while running, a long racing time, and BMI extremes were associated with hyponatremia, whereas female sex, composition of fluids ingested, and use of NSAIDs were not^{ref1, ref2}.
• basketball

Web resources : Basketball at CDC
• skateboarding

Web resources : Skates and skateboarding at CDC
• skiing, sledding and snowboarding : in 1983, Oh and Schmid argued that helmet use should be mandatory in skiers up to the age of 17 owing to the risk of severe head injuries^ref. Guided by compelling evidence that helmets are effective at preventing head, brain, and facial injuries in bicyclists, helmet use would seem to be reasonable^ref. Helmets are not yet widely recommended in skiers and snowboarders because of the paucity of information on their effectiveness. The best evidence suggests they are protective, but this was based on a study that was restricted to participants aged < 13 years, had a small sample size, and lacked control for potential confounders^ref. Helmets may increase the risk of spinal injury owing to the biomechanics of the association between the helmet and the head and neck^ref—a particular concern for children, who have a greater head to body ratio. A helmet may exert large bending or twisting forces on the neck in the event of an otherwise "routine" fall. Wearing a helmet while skiing or snowboarding may reduce the risk of head injury by 29% to 56%—that is, for every 10 people who wear helmets, three to six may avoid head injuries. This may even be an underestimate if, as in cycling, the helmets were worn incorrectly or were in poor condition, or were not designed for skiing or snowboarding. The effect of helmet use on neck injuries is less clear. Although a study found no statistically significant estimates for neck injury and no evidence of effect modification by age, their sensitivity analysis suggests an increased risk of neck injuries with helmet use^ref.

Web resources : Skiing, sledding, snowboarding at CDC
• prevention of ankle injuries

Ankle injuries are the most common, with an incidence of 1 per 100 000 people a day, accounting for about 20% of all sports injuries. Most ankle injuries are moderate ligament sprains. With proper functional treatment the patient can return to work or sport within a few weeks or even days, and most injuries heal without sequelae. Some ankle sprains, however, cause prolonged disability in the form of persisting pain or instability. The protective effects of taping and bracing have been shown persuasively in soccer and basketball, but only for players with previous ankle injury^{ref1, ref2, ref3}. Taping or bracing reduces the incidence of sprains and results in less severe sprains, whereas the efficacy of "high top" basketball shoes is unclear. Braces seem to be more effective than tape in preventing ankle sprains^{ref1, ref2}. Bracing is also more comfortable and more cost effective if used long term^{ref1, ref2}. Different types of braces are widely available commercially. Taping can be performed by the doctor, physiotherapist, or even the patient with a little instruction.

An ankle brace (right ankle) or tape (left ankle) should be worn during sporting an