The Neuromuscular Control Mechanism Of Functional Ankle Instability And Effectiveness Of Proprioceptive Neuromuscular Facilitation

Objectives:Functional Ankle Instability (FAI) was a disability condition related with repeat ankle sprain. The underlying reason was unknown and the effective of treatment was doubted. The purpose of this study was to investigate the kinematics and kinetics of single-leg jumping test with FAI. Muscle activation pattern, which involved pre-programme activity and reactional activity, proprioception and the range of motion in three dimensional plane were analyzed. The application of Proprioception Neuromuscular Facilitation to FAI was in progress. In order to explore the neuromuscular control mechanism of FAI and effectiveness of PNF.Methods:28 unilateral FAI males and 28 males without low limb injury experience were tested. With single-leg jumping test, the range of motion in three dimensional plane and sEMG of 5 key muscles was collected by BTS SMART-D Integrate Motion Analysis System. Proprioception of active closed-chain was assessed. Testing was repeated after 4 weeks PNF application.Result:①Muscle activation time pre-contact was significant difference in FAI group(P<0.05), biceps femoris delaied(P<0.05), tibial anterior and gastronimus lateralis advanced (P<0.05).②Muscle activation rate of tibial anterior and gastronimus lateralis pre-contact were significant difference(P<0.05), there was no difference post-contact (P>0.05).③There was significant difference in sagittal plane momvent, knee flexion increased and ankle plantar flexion decreased. (P<0.05), no difference in coronal plane and horizontal plane (P>0.05);④After PNF training, muscle activation time of biceps femoris was significant improved(P<0.05), and gastronimus lateralis activation pattern improved to control group level(P< 0.05). There were significant difference in tibial anterior activation pattern and angles of sigittal plane after training. (P<0.05);⑤There were significant difference in active close-chain proprioception assessment. The average length error of medial-lateral direction and average of trace error of multidiretion increased in FAI group (P<0.05), both of them decreased to control group level after PNF training (P>0.05);⑥After PNF training, ankle joint functional assessment score increased and the frenqucy of giving way decreased (P<0.05)。Conclusions:①During single leg jumping test, kinesiology, kinematic and muscle activation changed with functional ankle instability. Feedfoward and feedback of neuromuscular control changed.②Gastronimus lateral is and tibial anterior were the key muscles of feedfoward neuromusclar control of functional ankle instability.③D2 pattern of PNF training modified muscle activation pattern both pre-and post-contact, changed neuromuscular control of proximal joint, improved proprioception. PNF was effective to improve ankle stability and function of FAI.