Research On The Characteristics Of Lower Limb Neuromuscular Control During Landing Movements In People With Genu Varus

Purposes: To compare the effects and interactions of genu varus,lateral and fatigue factors on landing cushioning strategy and muscle activation,so to explore the changes of lower limb neuromuscular control characteristics of genu varus population,so to put forward reasonable exercise suggestions for genu varus population.Methods: 12 male college students with genu varus were randomly recruited as the experimental group and 12 male college students with normal lower limb morphology as the control group.Using 8-lens infrared high-speed motion capture system,three-dimensional force measuring platform and 14 channels portable wireless telemetry surface electromyography,the kinematics,dynamics and surface electromyography signals of both lower limbs during the landing movement of 45 cm platform before and after the bicycle fatigue scheme were tested simultaneously.Results:(1)Compared with the control group,the hip abduction angle,knee adduction angle,peak hip abduction torque,hip external rotation torque and knee internal rotation torque in the experimental group increased significantly at the moment of left landing(P < 0.05),and the peak plantar flexion torque decreased significantly(P < 0.05);However,the hip flexion torque,hip external rotation torque and plantar flexion torque at the moment of right landing decreased significantly(P < 0.05),and the knee adduction torque and knee internal rotation torque increased significantly(P < 0.05).In the experimental group,the stiffness of both ankles increased significantly(P < 0.05),and the contribution rate of energy absorption of left hip and knee decreased significantly(P <0.05).(2)Compared with the control group,in the pre-activation stage,the RMS and i EMG of medial femoral muscle in the experimental group were significantly increased(P <0.05),the MPF values of lateral gastrocnemius and medial gastrocnemius were significantly decreased(P < 0.05),the VM / VL was significantly increased(P < 0.05),and the co-activation ratio of hip muscle was significantly reduced(P < 0.05).In the post activation stage,RMS and i EMG of lateral gastrocnemius,rectus femoris and biceps femoris increased significantly(P < 0.05),MPF of biceps femoris,medial femoris and lateral gastrocnemius decreased significantly(P < 0.05),and the co-activation ratio and VM / VL ratio of hip muscles increased significantly compared with the control group(P< 0.05).(3)The lateral factors have a significant impact on the kinematic and dynamic indexes.There were significant differences in peak hip extension torque,peak plantar flexion torque,hip abduction angle at touchdown,knee internal rotation torque and peak knee internal rotation torque at touchdown,ankle valgus torque at touchdown,and contribution of energy absorption in sagittal plane of hip joint and knee joint in patients with genu varus(P < 0.05).(4)Fatigue has a significant effect on the characteristics of muscle activation.The MPF of rectus femoris,lateral gastrocnemius,and i EMG,RMS and MPF of biceps femoris in the experimental group were significantly different from those before fatigue(P < 0.05).In addition,in the post activation stage,the co-activation ratio of right hip muscle after fatigue was significantly lower than that before fatigue(P < 0.05),and the co-activation ratio of right knee muscle was significantly higher than that before fatigue(P < 0.05).Conclusion:(1)The load of coronal plane and horizontal plane in the landing stage of genu varus population increases significantly,corresponding to the decrease of sagittal plane load,suggesting that the exercise of the three planes will affect each other.Therefore,exercise should also pay attention to the exercise of maintaining the stable muscle strength related to lateral and rotational movement.(2)In the pre-activation and post activation stages of knee varus,the activation amplitude of medial femoral muscle and lateral gastrocnemius muscle increased,and the activation of rectus femoris and biceps femoris muscle increased after fatigue,suggesting that one of the neuromuscular control strategies of knee varus is to increase the activation of medial femoral muscle and lateral gastrocnemius muscle to stabilize the knee joint,and the other is to increase the co-activation of rectus femoris and biceps femoris.(3)When genu varus occurs,the coronal plane and horizontal plane load incline more to the left,and the capacity of buffering load on the left is weaker than that on the right.This imbalance will accelerate the injury process of unilateral knee osteoarthritis of the left leg.Therefore,it is suggested that people with genu varus should pay attention to the exercise of motor coordination ability of both lower limbs and strengthen the development of lateral strength of left lower limb muscles.(4)With the accumulation of exercise time,the muscle compensation activation of flexor and extensor muscles in genu varus population may become more and more obvious,and the biomechanical injury risk did not change significantly.