Gender Differences in Time-Frequency EMG Analysis of Unanticipated Cutting Maneuvers

Abstract

Female athletes adopted a different motor unit recruitment strategy that was particularly evident at, and near, IC resulting in lower frequency components in the EMG signal of the lateral hamstring. This strategy may play a role in explaining the gender bias in anterior cruciate ligament (ACL) injury rates. Gender differences in knee kinematics were also observed, exposing the female ACL to higher strain, which may be the result of differences in neuromuscular strategies to stabilize the knee joint.

Ativação muscular do quadril e do joelho em duas aterrissagens realizadas por atletas do sexo masculino

“…However, data analysis of the female population in the study by Hanson et al (18) and Tillman et al (6) suggest that the gender may be an important variable concerning the activation of this musculature, constituting in a potential factor for injury in the ACL in women (10) . Besides gender, other factors which can have influenced on these differences between studies, such as training status (29) , the sport practiced by the tested individuals (30) and the motor conducts used in the test, since to some studies used running with change of direction (18,31) and other different jump and landing types (1,7,17,29) . However, even if all variables were controlled, there could have been discrepancy in the results of the studies in the literature, since the study by Fagenbaum and Darling (17) demonstrated high variability of the activation of the biceps femoris between trials, corroborated in the present study through the high variation coefficient (table 1), which generates the hypothesis of different strategies of motor coordination based on the absence of global strategies, making the individual strategies necessary (32) .…”

Biomechanical Adaptations After Fatiguing Exercise in Healthy and ACL Reconstructed Individuals

“…Greater pelvic rotation increases stride length and may be a compensatory pattern to fatigue without increasing hip flexion. 57 Increased stride length is associated with increased impact shock, 19,63 which must be attenuated at the joint when the knee is extended.…”

“…60,199,202 121,195 Therefore, it is imperative that return to sport assessments for this population include functional assessments during exercise when risk of second injury is greatest and neuromuscular control is compromised. 19,28,173 Individuals with ACLR exhibit muscular and biomechanical adaptations after exercise. These changes include decreased hip flexion angle, external hip flexion moment, and increased external knee flexion moment during jogging.…”

“…4,5,63,69,86 This increased risk of injury during games may be due to adaptive movement patterns responding to unanticipated events, including increased lateral trunk flexion, knee abduction moment, and decreased hip abduction. 19,87 Knee valgus and trunk motion have been associated with increased risk of ACL injury. 58,67,85,100,146 Although prevention programs are appropriate for educating patients about risky movement patterns, 67 athletes often do not consider knee alignment and movement patterns at the end of games when athletes are fatigued.…”

“…118,166 Furthermore, athletes display altered kinematics and muscle recruitment strategy during unanticipated maneuvers in a fatigued state, indicating that injury risk may increase with neuromuscular and cognitive fatigue. 19,28,173 This study served as the first step to identifying adaptive movement patterns in individuals with ACLR after a bout of sport-specific fatiguing exercise. This information will help guide return to play decision-making after ACLR.…”