Effect of Lower Limb Muscle Fatigue on Knee Joint Control Strategies during Landing in Young Men

Fatigue is thought to affect the anterior cruciate ligament injury risk; thus, the present study was conducted to investigate kinematics, kinetics, and active muscle control strategies of the knee joint in fatigue conditions during a landing task.
A total of 15 healthy active male individuals (age: 22.09± 3.18 years; height: 58/7 ± 177 cm; weight: 72/7 ± 71 kg) participated in the current quasi-experimental study. Sit to stand fatigue protocol was used for lower limb fatigue and kinematic and kinetic and muscle activity during normal gait before and after fatigue protocol were collected. Shapiro-Wilk test was used to ensure the normal distribution of data and paired t-test was run to compare variables at p≤0.05 level.
Increased knee flexion velocities (P=0.004), increased knee flexion angle at initial foot contact (p=0.016), and peak knee flexion angle (p According to the supportive role of gastrocnemius and hamstrings muscles and contribution of this muscle with ACL ligament at knee joint stability, it seems that lower limb fatigue can lead to ACL injury and reduction of the stability of the knee. Increased flexion angle at foot contact, reduced ground reaction force, and increased time to pike may be related to the nervous system strategy to shock absorption and reduce injury of lower limb joints.