The sudden cardiac deaths of 387 young American athletes (under age 35) were analyzed in a 2003 medical review:

While most causes of sudden cardiac death relate to congenital or acquired cardiovascular disease, an exception is commotio cordis, in which the heart is structurally normal but a potentially fatal loss of rhythm occurs because of the accident of timing of a blow to the chest. Its fatality rate is about 65% even with prompt CPR and defibrillation, and more than 80% without.

Age 35 serves as an approximate borderline for the likely cause of sudden cardiac death. Before age 35, congenital abnormalities of the heart and blood vessels predominate. These are usually asymptomatic prior to the fatal event, although not invariably so. Congenital cardiovascular deaths are reported to occur disproportionately in African-American athletes.

After age 35, acquired coronary artery disease predominates (80%), and this is true regardless of the athlete's former level of fitness.

Screening athletes for cardiac disease can be problematic because of low prevalence and inaccurate performance of various tests that have been used. Nevertheless, sudden death among seemingly healthy individuals attracts much public and legislator attention because of its visible and tragic nature.

As an example, the Texas Legislature appropriated US$1 million for a pilot study of statewide athlete screening in 2007. The study employed a combination of questionnaire, examination and electrocardiography for 2,506 student athletes, followed by echocardiography for 2,051 of them, including any students with abnormal findings from the first three steps. The questionnaire alone flagged 35% of the students as potentially at risk, but there were many false positive results, with actual disease being confirmed in less than 2%. Further, a substantial number of screen-positive students declined repeated recommendations for follow-up evaluation. (Individuals who are conclusively diagnosed with cardiac disease are usually told to avoid competitive sports.) It should be stressed that this was a single pilot program, but it was indicative of the problems associated with large-scale screening, and consistent with experience in other locations with low prevalence of sudden death in athletes.

Cheating at the Paralympic Games has caused scandals that have significantly changed the way in which the International Paralympic Committee (IPC) manages the events.

Testing for performance-enhancing drugs has become increasingly strict and more widespread throughout the Games, with powerlifting seeing the most positive results. Competitors without disabilities have also competed in some Paralympic Games, with the Spanish entry in the intellectually disabled basketball tournament at the 2000 Summer Paralympics being the most controversial.

Commotio cordis may also occur in other situations, such as in children who are punished with blows over the precordium, cases of torture, and frontal collisions of motor vehicles (the impact of the steering wheel against the thorax, although this has decreased substantially with the use of safety belts and air bags). In one fatality, the impact to the chest was the result of an exploding whipping cream canister.

In contrast, the precordial thump (hard blows given over the precordium with a closed fist to revert cardiac arrest) is a sanctioned procedure for emergency resuscitation by trained health professionals witnessing a monitored arrest when no equipment is at hand, endorsed by the latest guidelines of the International Liaison Committee on Resuscitation. It has been discussed controversially, as—in particular in severe hypoxia—it may cause the opposite effect (i.e., a worsening of rhythm—commotio cordis). In a normal adult, the energy range involved in the precordial thump is five to 10 times below that associated with commotio cordis.

Commotio cordis is a very rare event, but nonetheless is often considered when an athlete presents with sudden cardiac death. Some of the sports which have a risk for this cause of trauma are baseball, American football, association football, ice hockey, polo, rugby football, cricket, softball, pelota, fencing, lacrosse, boxing, karate, kung fu, and other martial arts. Children are especially vulnerable, possibly due to the mechanical properties of their thoracic skeleton. From 1996 to spring 2007, the USA National Commotio Cordis Registry had 188 cases recorded, with about half occurring during organized sports. Almost all (96%) of the victims were male, the mean age of the victims during that period was 14.7 years, and fewer than one in five survived the incident.

Doping in Russian sports has a systemic nature. Russia has had 51 Olympic medals stripped for doping violations – the most of any country, four times the number of the runner-up, and more than a third of the global total. From 2011 to 2015, more than a thousand Russian competitors in various sports, including summer, winter, and Paralympic sports, benefited from a cover-up.

Side effects in women include:

- hair loss

- male pattern baldness

- hypertrophy of the clitoris

- increased sex drive

- irregularities of the menstrual cycle

- development of masculine facial traits

- increased coarseness of the skin

- premature closure of the epiphysis

In countries where the use of these drugs is controlled, there is often a black market trade of smuggled or counterfeit drugs. The quality of these drugs may be poor and can cause health risks. In countries where anabolic steroids are strictly regulated, some have called for a regulatory relief. Steroids are available over-the-counter in some countries such as Thailand and Mexico.

In sports where physical strength is favored, athletes have used anabolic steroids, known for their ability to increase physical strength and muscle mass. The drug mimics the effect of testosterone and dihydrotestosterone in the body. They were developed after Eastern Bloc countries demonstrated success in weightlifting during the 1940s. At the time they were using testosterone, which carried with it negative effects, anabolic steroids were developed as a solution. The drug has been used across a wide range of sports from football and basketball to weightlifting and track and field. While not as life-threatening as the drugs used in endurance sports, anabolic steroids have negative side effects, including:

Yunnan sudden death syndrome is a label used to define unexplained cases of cardiac arrest, which afflicted significant numbers of rural villagers in Yunnan province, in southwest China. Cases occurred almost always during the midsummer rainy season (from June to August), at an altitude of . The cause turned out to be a mushroom now blamed for an estimated 400 deaths in the past three decades.

The mysterious fatalities were recorded for decades before researchers from the Chinese Center for Disease Control and Prevention isolated a significant factor common in every case: a tiny unknown mushroom which was unintentionally gathered and consumed during wild mushroom harvests in the region. Previously the syndrome was thought to be caused by Keshan disease, caused by the Coxsackie virus.

The mushroom, "Trogia venenata", is also known as 'Little White'. It has been determined that families collecting fungi to sell have been eating these Little White mushrooms as they have no commercial value. Three amino acids present in the mushrooms have been shown to be toxic. The mushrooms have also been shown to contain very high quantities of barium, and it may be that some of the deaths are simply from barium poisoning.

In the hours before death, about two-thirds of the victims had such symptoms as nausea, dizziness, heart palpitations, seizures and fatigue.

However, in December 2012 it was announced that Dr Xu Jianping (徐建平) has been collecting samples of "Trogia venenata" in Yunnan for the past three years, and his research now shows that barium levels in the wild mushroom are no higher than those of common foods such as poultry and fish. Nonetheless, it appears the mushroom will still likely play a role. Since publication of the widely circulated 2010 "Science" article, no instances of Yunnan sudden death syndrome have been reported.

The World Anti-Doping Agency (WADA) is the main regulatory organization looking into the issue of the detection of gene doping. Both direct and indirect testing methods are being researched by the organization. Directly detecting the use of gene therapy usually requires the discovery of recombinant proteins or gene insertion vectors, while most indirect methods involve examining the athlete in an attempt to detect bodily changes or structural differences between endogenous and recombinant proteins.

Indirect methods are by nature more subjective, as it becomes very difficult to determine which anomalies are proof of gene doping, and which are simply natural, though unusual, biological properties. For example, Eero Mäntyranta, an Olympic cross country skier, had a mutation which made his body produce abnormally high amounts of red blood cells. It would be very difficult to determine whether or not Mäntyranta's red blood cell levels were due to an innate genetic advantage, or an artificial one.

Gene doping is the hypothetical non-therapeutic use of gene therapy by athletes in order to improve their performance in those sporting events which prohibit such applications of genetic modification technology, and for reasons other than the treatment of disease. , there is no evidence that gene doping has been used for athletic performance-enhancement in any sporting events. Gene doping would involve the use of gene transfer to increase or decrease gene expression and protein biosynthesis of a specific human protein; this could be done by directly injecting the gene carrier into the person, or by taking cells from the person, transfecting the cells, and administering the cells back to the person.

The historical development of interest in gene doping by athletes and concern about the risks of gene doping and how to detect it moved in parallel with the development of the field of gene therapy, especially with the publication in 1998 of work on a transgenic mouse overexpressing insulin-like growth factor 1 that was much stronger than normal mice, even in old age, preclinical studies published in 2002 of a way to deliver erythropoietin (EPO) via gene therapy, and publication in 2004 of the creation of a "marathon mouse" with much greater endurance than normal mice, created by delivering the gene expressing PPAR gamma to the mice. The scientists generating these publications were all contacted directly by athletes and coaches seeking access to the technology. The public became aware of that activity in 2006 when such efforts were part of the evidence presented in the trial of a German coach.

Scientists themselves, as well as bodies including the World Anti-Doping Agency (WADA), the International Olympic Committee, and the American Association for the Advancement of Science, started discussing the risk of gene doping in 2001, and by 2003 WADA had added gene doping to the list of banned doping practices, and shortly thereafter began funding research on methods to detect gene doping.

Genetic enhancement includes manipulation of genes or gene transfer by healthy athletes for the purpose of physically improving their performance. Genetic enhancement includes gene doping and has potential for abuse among athletes, all while opening the door to political and ethical controversy.

What follows is a list of all the athletes that have tested positive for a banned substance either during or before an Asian Games in which they competed. Any medals listed were revoked.

Risk factors for developing shin splints include:

- Excessive pronation at subtalar joint

- Excessively tight calf muscles (which can cause excessive pronation)

- Engaging the medial shin muscle in excessive amounts of eccentric muscle activity

- Undertaking high-impact exercises on hard, noncompliant surfaces (ex: running on asphalt or concrete)

- Smoking and low fitness level

While medial tibial stress syndrome is the most common form of shin splints, compartment syndrome and stress fractures are also common forms of shin splints. Females are 1.5 to 3.5 times more likely to progress to stress fractures from shin splints. This is due in part to females having a higher incidence of diminished bone density and osteoporosis.

Women in sports such as association football, basketball, and tennis are significantly more prone to ACL injuries than men. The discrepancy has been attributed to gender differences in anatomy, general muscular strength, reaction time of muscle contraction and coordination, and training techniques.

Gender differences in ACL injury rates become evident when specific sports are compared. A review of NCAA data has found relative rates of injury per 1000 athlete exposures as follows:

- Men's basketball 0.07, women's basketball 0.23

- Men's lacrosse 0.12, women's lacrosse 0.17

- Men's football 0.09, women's football 0.28

The highest rate of ACL injury in women occurred in gymnastics, with a rate of injury per 1000 athlete exposures of 0.33

Of the four sports with the highest ACL injury rates, three were women's – gymnastics, basketball and soccer.

According to recent studies, female athletes are two to eight times more likely to strain their anterior cruciate ligament (ACL) in sports that involve cutting and jumping as compared to men who play the same particular sports (soccer, basketball, and volleyball). Differences between males and females identified as potential causes are the active muscular protection of the knee joint, the greater Q angle putting more medial torque on the knee joint, relative ligament laxity caused by differences in hormonal activity from estrogen and relaxin, intercondylar notch dimensions, and muscular strength.

SIDS rates decrease with increasing maternal age, with teenage mothers at greatest risk. Delayed or inadequate prenatal care also increases risk. Low birth weight is a significant risk factor. In the United States from 1995 to 1998, the SIDS death rate for infants weighing 1000–1499 g was 2.89/1000, while for a birth weight of 3500–3999 g, it was only 0.51/1000. Premature birth increases the risk of SIDS death roughly fourfold. From 1995 to 1998, the U.S. SIDS rate for births at 37–39 weeks of gestation was 0.73/1000, while the SIDS rate for births at 28–31 weeks of gestation was 2.39/1000.

Anemia has also been linked to SIDS (note, however, that per item 6 in the list of epidemiologic characteristics below, extent of anemia cannot be evaluated at autopsy because an infant's total hemoglobin can only be measured during life.). SIDS incidence rises from zero at birth, is highest from two to four months of age, and declines toward zero after the infant's first year. Baby boys have a ~50% higher risk of SIDS than girls.

Although strains are not restricted to athletes and can happen while doing everyday tasks, however, people who play sports are more at risk for developing a strain. It should also be noted that it is common for an injury to develop when there is a sudden increase in duration, intensity, or frequency of an activity.

Breastfeeding is associated with a lower risk of SIDS. It is not clear if co-sleeping among mothers who breastfeed without any other risk factors increased SIDS risk.

After return of heart function, there has been a moderately higher risk of death in the hospital when compared to MI patients without PVF. Whether this still holds true with the recent changes in treatment strategies of earlier hospital admission and immediate angioplasty with thrombus removal is unknown. PVF does not affect the long-term prognosis.

The risk factors for SCD are similar to those of coronary artery disease and include age, cigarette smoking, high blood pressure, high cholesterol, lack of physical exercise, obesity, diabetes, and family history. A prior episode of sudden cardiac arrest also increases the risk of future episodes.

Current cigarette smokers with coronary artery disease were found to have a two to threefold increase in the risk of sudden death between ages 30 and 59. Furthermore, it was found that former smokers risk was closer to that of those who had never smoked.

A stinger is an injury that is caused by restriction of the nerve supply to the upper extremity via the brachial plexus. The brachial plexus is formed by the anterior rami of the nerves at the 5th cervical level of the spinal cord all the way to the nerves at the 1st thoracic level of the spinal cord. The brachial plexus innervates the upper extremity as well as some muscles in the neck and shoulder. Damage to the brachial plexus can occur when the nerves are stretched too far from the head and neck; specifically the upper trunk of the plexus –nerve roots at the 5th and 6th cervical level –are primarily affected. The upper trunk provides part of the nerve to supply to the upper extremity via the Musculocutaneous, Axillary, Radial and Median nerves. It is for this reason that stingers do not affect both arms simultaneously, however it is possible for both arms to accrue injuries. Repeated nerve trauma can cause recurring stingers, chronic pain, and muscle weakness, while recovery can take weeks to months in severe cases.

The overall chance of survival among those who have cardiac arrest outside hospital is 10%. Among those who have an out-of-hospital cardiac arrest, 70% occur at home and have a survival rate of 6%. For those who have an in-hospital cardiac arrest, survival rate is estimated to be 24%. Among children rates of survival is 3 to 16% in North America. For in hospital cardiac arrest survival to discharge is around 22% with many having a good neurological outcome.

Prognosis is typically assessed 72 hours or more after cardiac arrest. Rates of survival are better in those who someone saw collapse, got bystander CPR, or had either ventricular tachycardia or ventricular fibrillation when assessed. Survival among those with Vfib or Vtach is 15 to 23%. Women are more likely to survive cardiac arrest and leave hospital than men.

A 1997 review found rates of survival to discharge of 14% although different studies varied from 0-28%. In those over the age of 70 who have a cardiac arrest while in hospital, survival to hospital discharge is less than 20%. How well these individuals are able to manage after leaving hospital is not clear.

A study of survival rates from out-of-hospital cardiac arrest found that 14.6% of those who had received resuscitation by ambulance staff survived as far as admission to hospital. Of these, 59% died during admission, half of these within the first 24 hours, while 46% survived until discharge from hospital. This reflects an overall survival following cardiac arrest of 6.8%. Of these 89% had normal brain function or mild neurological disability, 8.5% had moderate impairment, and 2% had major neurological disability. Of those who were discharged from hospital, 70% were still alive four years later.

Athlete's heart is not dangerous for athletes (though if a nonathlete has symptoms of bradycardia, cardiomegaly, and cardiac hypertrophy, another illness may be present). Athlete's heart is not the cause of sudden cardiac death during or shortly after a workout, which mainly occurs due to hypertrophic cardiomyopathy, a genetic disorder.

No treatment is required for people with athletic heart syndrome; it does not pose any physical threats to the athlete, and despite some theoretical concerns that the ventricular remodeling might conceivably predispose for serious arrhythmias, no evidence has been found of any increased risk of long-term events. Athletes should see a physician and receive a clearance to be sure their symptoms are due to athlete’s heart and not another heart disease, such as cardiomyopathy. If the athlete is uncomfortable with having athlete's heart or if a differential diagnosis is difficult, deconditioning from exercise for a period of three months allows the heart to return to its regular size. However, one long-term study of elite-trained athletes found that dilation of the left ventricle was only partially reversible after a long period of deconditioning. This deconditioning is often met with resistance to the accompanying lifestyle changes. The real risk attached to athlete's heart is if athletes or nonathletes simply assume they have the condition, instead of making sure they do not have a life-threatening heart illness.

The survival of PVF largely depends on the promptness of defibrillation. The success rate of prompt defibrillation during monitoring is currently higher than 95%. It is estimated that the success rate decreases by 10% for each additional minute of delay.

Sports involving repetitive or forceful hyperextension of the spine, especially when combined with rotation are the main mechanism of injury for spondylolysis. The stress fracture of the pars interarticularis occurs on the side opposite to activity. For instance, for a right-handed player, the fracture occurs on the left side of the vertebrae.

Spondylolysis has a higher occurrence in the following activities:

- Baseball

- Tennis

- Diving

- Cheerleading

- Gymnastics

- Football

- Soccer

- Wrestling

- Weightlifting

- Roller Derby

- Cricket

- Pole Vault

- Rugby

- Volleyball

- Gym

- Ultimate Frisbee (especially during impact from laying out)

Although this condition can be caused by repetitive trauma to the lumbar spine in strenuous sports, other risk factors can also predispose individuals to spondylolsis. Males are more commonly affected by spondylolysis than females. In one study looking at youth athletes, it was found that the mean age of individuals with spondylolisthesis was 20 years of age. Spondylolysis also runs in families suggesting a hereditary component such as a predisposition to weaker vertebrae.

In medicine, a stinger, also called a "burner" or "nerve pinch injury", is a neurological injury suffered by athletes, mostly in high-contact sports such as ice hockey, rugby, American football, and wrestling. The spine injury is characterized by a shooting or stinging pain that travels down one arm, followed by numbness and weakness. Many athletes in contact sports have suffered stingers, but they are often unreported to medical professionals.

Anyone who experiences significant trauma to his or her head or neck needs immediate medical evaluation for the possibility of a spinal injury. In fact, it's safest to assume that trauma victims have a spinal injury until proven otherwise because:

- The time between injury and treatment can be critical in determining the extent of complications and the amount of recovery

- A serious spinal injury is not always immediately obvious. If it is not recognized, more severe injury may occur

- Numbness or paralysis may develop immediately or come on gradually as bleeding or swelling occurs in or around the spinal cord