What are gender differences in lower limb muscle activity during jump-landing tasks? A systematic review and meta-analysis.

BACKGROUND: Gender differences in muscle activity during landing have been proposed as a possible contributing factor to the greater incidence of anterior cruciate ligament injuries in women. Conflicting results among a few studies in this regard makes it impossible to reach correct conclusions. OBJECTIVES: The aim of this study was systematic review and the meta-analysis of previous studies which have compared the electromyographic activity of lower limb muscles in gluteus muscles (maximus and medius), quadriceps (rectus femoris, vastus medialis and lateralis), hamstrings (biceps femoris and semimembranosus), and gastrocnemius in men and women in jump-landing task. METHODS: A systematic search of the PubMed, SCOPUS, Science Direct databases was performed for eligible articles in October 2020. Cross-sectional studies that compared the muscle activity of male and female athletes without a history of previous injury in the jump-landing task were included. Unisex and non-athlete's studies were extracted from the included studies. The data were synthesized using a fixed and random effects model. RESULTS: Eight studies involving 145 participants were included. All participants were people who participated in regular exercises. The meta-analysis of timing and muscle activity was performed in the feedforward (pre contact) and feedback (post contact) stages. There were no significant differences in the muscle activity of biceps femoris (MD = -12.01; 95% CI - 51.49 to 27.47; p = 0.55; I2 = 87%), vastus medialis (MD = -53.46; 95% CI - 129.73 to 22.81; p = 0.17; I2 = 91%), semimembranosus (MD = 1.81; 95% CI - 6.44 to 10.07; p = 0.67; I2 = 0%), gluteus medius (MD = -3.14; 95% CI - 14.24 to 7.96; p = 0.58; I2 = 48%), and rectus femoris (MD = -5.83; 95% CI - 14.57 to 2.92; p = 0.19; I2 = 87%) in the pre contact phase between two sexes. There was a significant difference between men and women in the activity of vastus lateralis muscle in the post contact phase (MD = -34.90; 95% CI - 48.23 to - 21.57). No significant difference was observed between the men and women in the timing of semimembranosus (MD = 23.53; 95% CI - 14.49 to 61.54; p = 0.23; I2 = 56%) and biceps femoris muscle activity (MD = -46.84; 95% CI - 97.50 to 3.83; p = 0.07; I2 = 82%). CONCLUSION: The results showed that in all lower limb muscles except vastus lateralis there were no significant differences between muscle activity and muscle contraction timing in both sexes before and after foot contact. Therefore, it can be concluded that the reason for the greater susceptibility of ACL injuries in women than men is maybe related to other factors such as biomechanical and hormonal. Additional good quality research in this regard is required to strengthen these conclusions.

Hop Stabilization Training Improves Neuromuscular Control in College Basketball Players With Chronic Ankle Instability: A Randomized Controlled Trial.

CONTEXT: Neuromuscular control deficit has been reported in people with chronic ankle instability (CAI) and hopping exercises have been recommended as a functional training tool to prevent lower limb injury, but its effects on lower-extremity neuromuscular control in those with CAI are unclear. OBJECTIVE: To investigate the effect of hop stabilization training on neuromuscular control and self-reported function in college basketball players with CAI. STUDY DESIGN: A randomized controlled trial. SETTING: Research Laboratory. Patients (or Other Participants): A total of 28 college basketball players with CAI were randomly assigned to the experimental hop stabilization group (age = 22.78 [3.09] y, weight = 82.59 [9.51] kg, and height = 187.96 [7.93] cm) or the control group (age = 22.57 [2.76] y, weight = 78.35 [7.02] kg, and height = 185.69 [7.28] cm). INTERVENTION: Participants in the experimental group performed supervised hop stabilization exercises 3 times per week for 6 weeks. The control group received no intervention. MAIN OUTCOME MEASURES: Preparatory and reactive muscle activation levels and muscle onset time were assessed from 8 lower-extremity muscles during a jump-landing task before and after the 6-week training program. RESULTS: Significant improvements in preparatory muscle activation, reactive muscle activation, and muscle onset time were noted across the lower-extremity in the experimental group relative to the control group (P < .05). Self-reported function also improved in the experimental group relative to the control group (P < .05). CONCLUSIONS: These findings demonstrate that 6 weeks of hop stabilization training is effective in improving neuromuscular control and self-reported function in college basketball players with CAI. Hop stabilization exercises can be incorporated into the rehabilitation program for CAI.