A clear increase in the number of accidents can be noted for nearly all sports during early adolescence. This increase is of course because children of that age practice more sports but also because they take greater risks, especially boys, by practicing sports that are less well supervised than during childhood. It can be noted that the increase in the number of accidents during adolescence happens earlier and more suddenly in school sports especially (gymnastics and ball sports) which, by definition, are practiced by both boys and girls equally. This increase in injuries is followed by a peak then a decrease. In comparing the sexes and all sports combined, this peak occurs at 14 years old for boys and 12 years old for girls depending on the series [10, 31, 49, 53]. It corresponds to the pubescent growth spurt that occurs between 12 and 13 for girls and approximately a year or a year and a half later for boys. The puberty results in profound physical and psychological changes. These changes require major psychomotor readaptation and result in irregular physical performance, which can include a certain clumsiness, thus a greater risk of accidents. For Narring et al. [42] this is especially obvious at puberty because the morphological and psychological developmental changes of girls and boys differ. A lack of practice of motor skills during a period when the body needs to adapt to locomotor changes is certainly a handicap for girls and can increase their risk of accidents. Moreover, body mass increases, especially fat, while boys develop muscle. Thus girls have an unfavorable weight/strength ratio, which can create problems.

There are important differences between the sexes in the causes of injury. There are anatomical, physiological, and psychological criteria [8, 45] as well as differences according to the type of sports practiced. Male athletes seem to have a higher risk of severe sports-related injuries [47], while women are more affected by overuse than men [14, 26, 50, 61]. Distribution of sports injuries between the sexes in the literature is on average 60 % for boys and 40 % for girls, all sports included [15, 31, 51, 56, 58]. Certain studies reported a less marked difference with 51–55 % of injuries for boys [4, 30, 36, 44], while in other series there was a greater difference with 71 % of male injuries [10, 54]. This male predominance is logical if each sport is studied separately. It is most marked in football, where girls only represent 6.5 % of the cases. The only sports where the male predominance is reversed are volleyball, handball, gymnastics, horseback riding, and figure skating [5, 13, 22, 23, 27, 49, 51, 58]. Most of the time this male or female predominance can simply be explained by a greater participation of boys than girls in a specific sport: football and ice hockey are mainly male sports, while dance, skating, and horseback riding are more frequently practiced by girls. All sports combined, the types of injuries are basically the same for the two sexes even if there are some slight variations. The main injury in girls is sprains with a mean 21.5–44 % of sprains versus 16–24 % in boys [15, 29]. Hormonal factors are one of the most important risk factors explaining the difference between the sexes. Numerous studies have evaluated the risk factors of anterior cruciate ligament (ACL) tears in women (Table 2.1) and noted hormonal factors. We know that there are hormone receptors on the ACL in particular estrogen, progesterone, testosterone, and relaxin receptors. Although it is known that these receptors affect the metabolism and mechanical properties of the ACL, at present we do not know what the actual effects are [16, 18, 25, 37]. A review of the literature has shown that the frequency of ACL injuries is not constant during the menstrual cycle. There is a significantly greater frequency of tears during the preovulatory phase than during the postovulatory phase. The study by Wojtys clearly shows a greater prevalence of ACL tears (noncontact pivot) in female athletes during the preovulatory phase of the menstrual cycle [60], and other studies reach the same conclusion [1, 34, 52]. Severe sprains during the preovulatory phase were significantly more frequent than during the postovulatory phase (OR, 3.22). This distinction can be found in numerous epidemiological studies in particular the study by Dugan in 2005 [17], which showed that women athletes who practice sports involving jumps and intermittent efforts had a risk of knee injury that was two to six times greater than their male counterparts.

A significant increase in the intensity of training and changes in the type of activity in sports, and in particular in sports techniques are considered to be risk factors for injuries in the presence of deficient training. To prevent secondary injuries, athletes should receive high-quality training as well as the correct amount of training and recovery and have a healthy lifestyle. Training must absolutely follow strict criteria for regularity, progressivity, adaptation, and recovery. Training should always be preceded by a more or less lengthy warm-up period that is adapted to the specific sport. Warming-up prepares the body for the cardiovascular, pulmonary, muscular, and even psychological stresses to follow. The muscles, organs, and joints will receive better provisions of oxygen and nutrients when the real physical effort begins. To be effective, the warm-up process should follow certain basic rules: it should be long enough. If it is too short, the muscles will tire more quickly. It should be gradual: the effort should be gradually increased and performed faster until it reaches 50–60 % of the athlete’s total capacity. It should be adapted to the situation: the warm-up should be associated with general stretching and relaxation to prepare the muscles and joints for stresses and strains. This should be followed by movements specific to each sport. Increasing muscle strength is an integral part of training, to improve performance, but also to prevent accidents. Tonic and balanced muscle tone helps regulate the stresses and strains on tendons, bones, and joints during daily practice as well as under extreme or dangerous circumstances. Increasing the amount of training, especially suddenly, is associated with a corresponding increase in the number of accidental injuries. Thus for runners, the risk of injury increases when they run more than 35 to 40 kms per week. In the same way, so-called interval training, which alternates several acceleration phases with more or less long recovery phases, is the cause of musculotendinous accidents. Recovery is essential because it allows the body to gradually return to a state of rest. Unfortunately this phase is often too short or even nonexistent. There are different ways to recover: reduce the intensity of the exercises and the frequency of training or simply to rest. Finally a healthy lifestyle is essential for an athlete. Hydration that is regular, continuous, and slightly alkaline, taken before, during, and after training so that the athlete never reaches the threshold of thirst, which is frequently too late, is an effective way to prevent numerous cases of tendinitis. Also the phases of recovery following an effort and in particular the quality of sleep must absolutely be preserved to avoid overtraining. The sports doctor can also suggest a sport to a future athlete that she/he may not have considered but that could be better adapted to his/her morphology or physical capacities. This element is important for the person to be motivated by his/her results and enjoy practicing sports under optimal conditions.

The sports technique must be perfect; otherwise, injuries can develop: tennis elbow in amateur tennis players who practice a backhand with a non-stabilized wrist which overuses the epicondylar muscles [28] and injury to the posterior cubital tendon from repetitive topspin forehands causing excess tension in this tendon. Good quality equipment should be used that is adapted to the player (morphology and level of play). In tennis, to prevent tennis elbow a lighter racket should be used that is not strung too tightly (less than 23 kgs), with a handle that is not too long without forward balance to avoid overusing the elbow muscles. Good training equipment is essential to prevent sports-related accidents and overuse injury, called technopathies. For example, shoes that are adapted to the sport being played, to the terrain, as well as to the player’s weight and feet significantly reduce the risk of developing musculoskeletal problems. In the same way, a bicycle should be adapted and adjusted to the user’s morphology and age. Once again, the best advice can be given by trainers or sports doctors who have in-depth knowledge of the sport and its constraints. Based on their experience, athletes, even amateur athletes, can choose the material that is best adapted to them. For certain sports such as cycling, the equipment can be adapted by the morphology of each individual athlete by a specialist, an ergonomist.