Comparison of lower extremity electromyography activity between male and female athletes in the Jump - landing tasks: A systematic review

Women are two to eight times more likely than men to tear the anterior cruciate ligament. The most common mechanism of anterior cruciate ligament injury is non-contact, which accounts for about 72% of all ligament injuries and occurs during activities such as deceleration, jump landing, and cutting. Among these, jump-landing is the most commonly reported mechanism of ACL injury in sports, as an inappropriate technique during jump-landing manoeuvres can cause considerable force on the ACL and result in rupture. Although exercise manoeuvres lead to excessive loads on the knee in both sexes, these manoeuvres cause more injury to women. This significant increase in the incidence of injuries in women has led to extensive studies on gender differences. Therefore, the purpose of this systematic review was to the studies that compared the electromyography activity of the lower limb muscles in the jump-landing task between men and women.

Papers in English were searched in the Google Scholar, Science Direct, PubMed, WOS, Scopus, ProQuest, and Cochrane Library databases without time limitation until 2020 and with keywords related to "electromyography", "jump-landing", and "gender". Inclusion criteria included cross-sectional and gender comparisons studies in which samples were male and female athletes with no history of sports injury, the task was one or two jump–landing and lower extremity electromyography activity was measured before or after ground contact. The modified checklist of Downes (1998) was used to evaluate the quality of the studies.

Searching for selected keywords in different databases led to finding 1018 articles. Then duplicate articles were removed (415) and 603 articles and their abstracts were reviewed, and after the screening, 66 articles were studied in more detail. Seventeen articles were excluded from the review process due to differences in the type of assignment or unrelated information provided. Some studies provided information only about female athletes or did not directly compare men and women (33, 34)or the task presented in them was not according to our criteria (35). Finally, Eight articles were selected for a comprehensive review. Quality index score was obtained for all articles above 6, so the included articles had a desirable level in terms of quality. Numerous studies have examined muscle activation in the feedforward and feedback stages (before and after foot contact with the ground) during the jump landing task to determine gender differences and the causes of ACL injuries. The jump landing conditions studied include two-legged landings from heights of 20 and 40 cm (36), 30 cm (38) and jump-landings that are normalized with respect to the maximum vertical jump of the subjects (39). Sex differences in rectus femoris muscle activation were seen in one study (43) out of 5 studies (36, 39, 41, 43, 44). However, Ebben (39) showed that this muscle is used significantly earlier in women. Only Ebben (39) reported significant sex differences in external hamstring muscle activation so that men showed more activity before and after contact. Four studies (36, 39, 40, 42) examined the mean and maximum activity of internal extensor muscle. The results of Ebben study (39),which examined the timing of activity, showed that the vastus medialis muscle was activated earlier in women. Few authors have studied the activity of the medial and lateral gastrocnemius muscles. Rozzi (40) examined the lateral gastrocnemius muscle, and Rozzi and Zazulak (40, 43)studied gastrocnemius medial and in neither of them was there a significant difference between the two sexes while performing the jump landing task in this muscle. Activation of the gluteus medius muscle was measured in 4 studies (38, 42-44), and no significant difference was reported in the activation of the gluteus medius between the two sexes. Zazulak (43)studied the mean and maximum activity of the gluteus maximus muscle which showed that the mean and maximum muscle activity after foot contact with the ground is higher in men than women (43)but before contact with the ground, there is a significant difference between the two sexes. The results of studies examining the activity of the muscles of the rectus femoris, vastus medialis, vastus lateralis, medial hamstring, lateral hamstring, gastrocnemius and gluteus medius in the feedforward and feedback stages during the landing task were performed at different altitudes. There is no difference between men and women in terms of the muscle activation pattern.

The results showed that men and women show similar patterns of muscle activation before and after jump-landing when the intensity of the task is appropriate to their ability. Therefore, the cause of womenchr('39')s greater vulnerability should be sought in other cases such as biomechanical and hormonal factors. It was also found that the type of exercise and the level of physical fitness of individuals can affect the pattern of muscle activation..