Objective:To study the neuromuscular control characteristics of ankle muscles of patients with chronic ankle instability(CAI)in different phases of stance,in order to provide reference for function evaluation and interven-tion of CAI.Method:CAI patients were collected according to the inclusion and exclusion criteria and matched with healthy individuals based on age,height,weight and sex.Surface electromyography was used to detect the electromyographic activity of the tibialis anterior,peroneus longus,gastrocnemius medialis and lateralis in all subjects during barefoot walking at a self-selected speed.Result:Compare with the control group,the mean normalized root mean square(RMS)value and co-contrac-tion index of peroneus longus in CAI patients were significantly reduced from middle-stance to heel-off(P＜0.05).The normalized RMS of gastrocnemius medialis was significantly increased from heel-off to toe-off(P＜0.05).The co-contraction indexes of tibialis anterior(P＜0.01)and gastrocnemius lateralis(P＜0.05)was signif-icantly decreased from heel-strike to foot flat.Conclusion:In CAI patients during walking,the neuromuscular control of the peroneus longus is reduced from middle-stance to heel-off,and the neuromuscular activation of the gastrocnemius medialis was increased from heel-off to toe-off,while the neuromuscular control of tibialis anterior and gastrocnemius lateralis is sufficient from heel-strike to foot-flat.These abnormalities will affect the posture and movement of foot-ankle at the cor-responding gait phase and increase the risk of ankle sprain.

Objective:To study the neuromuscular control characteristics of ankle muscles of patients with chronic ankle instability(CAI)in different phases of stance,in order to provide reference for function evaluation and interven-tion of CAI.Method:CAI patients were collected according to the inclusion and exclusion criteria and matched with healthy individuals based on age,height,weight and sex.Surface electromyography was used to detect the electromyographic activity of the tibialis anterior,peroneus longus,gastrocnemius medialis and lateralis in all subjects during barefoot walking at a self-selected speed.Result:Compare with the control group,the mean normalized root mean square(RMS)value and co-contrac-tion index of peroneus longus in CAI patients were significantly reduced from middle-stance to heel-off(P＜0.05).The normalized RMS of gastrocnemius medialis was significantly increased from heel-off to toe-off(P＜0.05).The co-contraction indexes of tibialis anterior(P＜0.01)and gastrocnemius lateralis(P＜0.05)was signif-icantly decreased from heel-strike to foot flat.Conclusion:In CAI patients during walking,the neuromuscular control of the peroneus longus is reduced from middle-stance to heel-off,and the neuromuscular activation of the gastrocnemius medialis was increased from heel-off to toe-off,while the neuromuscular control of tibialis anterior and gastrocnemius lateralis is sufficient from heel-strike to foot-flat.These abnormalities will affect the posture and movement of foot-ankle at the cor-responding gait phase and increase the risk of ankle sprain.

Objective To explore the effect and mechanism of preventing ankle instability through exer-cise, so as to provide evidence-based references for practice. Methods The randomized and controlled trials ( RCT) on preventing ankle instability through exercise published before December 2014 were searched for in the NCBI, CNKI, VIP and Wanfang databases by computer, supplemented by manual searching. Each study′s quality was evaluated according to the standards of the Cochrane handbook by 3 researchers. The outcome indexes were ex-tracted and analyzed using RevMan 5.2 software. Results After the initial selection, 665 papers (357 in English and 308 in Chinese) were retained. From these 92 were chosen after reading the titles and abstracts. Ultimately, 14 RCT studies ( 12 in English and 2 in Chinese) met the inclusion criteria. They showed that exercise improved ankle function and symptoms of ankle instability significantly [SMD=0.98, 95%CI (0.65,1.31), P≤0.01], improved muscle strength [SMD=1.50, 95%CI (0.99,2.01), P≤0.01], improved balance and postural stability [SMD=-0.54, 95%CI (-0.84,-0.25) ,P≤0.01] , but did not improve proprioception or neuromuscular functioning sig-nificantly. Conclusions Exercise can effectively improve muscle strength, balance and postural stability, but not proprioception or neuromuscular functioning. The details of these findings may be related to the exercise intervention chosen.