Age-related Ankle Function And Neuromuscular Characteristics Of Male Recreational Runners

Purpose: The aim of the study is to investigate the characteristics of foot arch shape,ankle range of motion,ankle isometric strength,and s EMG in running gait in healthy male runners of different ages from 20 to 60 years old.And through investigating the changes of the above indices in different age groups after20-kilometer track and field run,we analyze the reasons for the differences and the relationship between age and above indices,so as to provide more scientific guidances for runners of different age groups in running training and running injury prevention.Methods: Select 63 healthy physically active male subjects between the ages of20 and 60 were divided into four groups: Group A(20～29 years old,N=14),Group B(30～39 years old,N=17),Group C(40～49 years old,N=16),and Group D(50～60years old,N=16).The foot posture index,normalized navicular height,ankle range of motion,ankle isometric strength and lower limbs s EMG while running at a speed of 3～3.3m/s were evaluated before and after a 20-kilometer track run,and record the fatigue level after running.Results:(1)Before running,the FPI of Group B,Group C and Group D was lower than that of Group A,the NNH of Group D was higher than that in Group A(P<0.05).After running,the FPI of Group C and Group D increased(P<0.05).The NNH of Group D decreased(P < 0.05).After covariance,the FPI of Group D was higher than that of Group B,and normalized navicular height was lower than that of Group B(P < 0.05);(2)Before running,there was no significant difference in active and passive ankle ROM in the four groups.The ROM of active and passive dorsiflexion after running decreased in Group D(P<0.05).After covariance,the activity of active inversion and dorsiflexion in Group D was lower than that in Group C(P < 0.05);(3)Before running,ankle inversion muscle strength in Group D was lower than that in Group C(P<0.05).After running,dorsiflexion and inversion muscle strength decreased in all four groups(P < 0.05).In addition,the eversion muscle strength in Group D also decreased(P < 0.05);(4)Before running,the RMS of tibialis anterior muscle during the pre-swing phase in Group D was less than that in Group A(P < 0.05).After running,the MPF of tibialis anterior muscle during the pre-swing phase and the stance phase of Group D significantly decreased(P < 0.05).After covariance,the RMS of tibial anterior muscle in Group D and at the loading stage was less than that in group C(P < 0.05),and that of group A at the loading stage was less than that of group C(P < 0.05);(5)During 20 km run,the pace of Group A and Group B was higher than that of Group D(P < 0.05),and the subjective fatigue level of Group D was higher than that of Group A,B and C(P < 0.05).Conclusion:(1)Under the load of 20 km run,runners will show a tendency of arch fatigue deformation.Older runners were also more likely to develop arch fatigue;(2)With the increase of age,there was no difference in the range of motion of the runners’ ankles,related to the high activity.After 20 km run,the active and passive dorsiflexion of ankle joint decreased in runners over 50 years old,related to tibial anterior muscle fatigue;(3)Before the age of 50,the strength of the runner’s ankle joint increased with age.The 20 km run will cause the decrease of the ankle flexion and inversion muscle strength of the runners..The runners aged 30 to 39 have a strong ability to maintain the ankle eversion muscle strength;(4)After a 20 km run,the tibialis anterior muscle of runners aged 40 to 49 has a strong anti-fatigue ability,while runners aged over 50 are prone to tibialis anterior muscle fatigue;(5)Runners between 30 and 39 years old performed the best in 20 km run,which may be related to the strong anti-fatigue and deformation ability of the arch.