| Objective: The study aimed to compare the possible effects of heel heights on human ankle biomechanics and static balance ability during normal walking.The applicability of different heels was evaluated by several parameters and related indicators to promote the application in the field of sports rehabilitation of lower extremity injury.Subjective and methods: Twelve male college students in Nanjing Sport Institute were enrolled.Three different heel heights(negative heels,flat shoes and barefoot)were used in this study.The data of gait spatial and temporal parameters,ground reaction force(GRF),ankle motion angle,ankle torque,the surface electromyography signal of main muscle around the joint,static balance ability and other indicators were collected.The indicators above were analyzed by oneway analysis of variance(ANOVA)at a significance level of P<0.05.Results:(1)The effects of different heel heights on gait parameters: the step length of negative-heel shoes group was larger than that of barefoot group(P<0.05).The step speed and stride rate of negative-heel shoes group was smaller than that of barefoot group(P<0.05).There were no significant differences in step width(P>0.05).The proportion of stance phase in negative heel shoes group was larger than that in barefoot group and flat shoes group(P<0.05).There were no significant differences in swing phase parameters(P>0.05).(2)The effects of different heel heights on the ground reaction force(GRF)of walking: the standardized GRF of negative-heel shoes and flat shoes were significantly larger than those of barefoot during the phase of left foot landing and off the ground(P<0.01).However,there were no significant differences between the negativeheel shoes group and the flat shoes group(P<0.05).There were no significant differences among the groups(P>0.05)in the left foot stance phase and the second peak stage.During the left foot off the ground,the standardized GRF of negativeheel shoes were significantly larger than those of flat shoes group and barefoot group(P<0.01).(3)The effects of different heel heights on ankle angles and moments: in sagittal plane,the metatarsal flexion angles of negative-heel shoes group and barefoot group was larger than that of flat shoes group(P<0.05).However,there were no significant differences between negative-heel shoes group and barefoot group(P>0.05).The metatarsal flexion moments of negativeheel shoes group were less than those of barefoot group(P<0.05).Besides,the dorsiflexion moments of flat shoes group were significantly larger than those of barefoot group(P<0.05).Moreover,the dorsiflexion moments of negative-heel shoes were larger than those of barefoot group and flat shoes group during the left foot stance phase(P<0.05).There were no significant differences in joint angles between the two groups in other phases(P>0.05),however,in the second peak period,the dorsiflexion moments in the flat shoes group were less than those in the barefoot group(P<0.05)while there were no significant differences from the negative-heel shoes group(P>0.05).In frontal plane,there were no significant differences in joint angle between the negative-heel shoes group during the left foot landing phase and stance phase(P>0.05).The joint angles between the negative-heel shoes group and the flat shoes group was significantly higher(P<0.01).Besides,the flat shoes group and the barefoot group were statistically different(P<0.05).The frontal eversion angles of the negative-heel shoes group and flat shoes group were significantly less than those of the barefoot group(P<0.01).During the left foot landing phase,there were no significant differences among the groups in left foot stance phase(P>0.05).The inversion moments of negative-heel shoes group and flat shoes group were larger than those of barefoot group(P<0.05),besides,there were no significant differences among the groups(P>0.05).(4)The characteristics of surface electromyography of main muscles around ankle joint: there were no significant differences in the integral electromyography(i EMG)and root mean square(RMS)of medial gastrocnemius among the different heel heights groups(P>0.05).As for the tibialis anterior muscle,the i EMG of negative-heel shoes group were significantly larger than those of barefoot group(P<0.01)and flat sole group(P<0.01).There were also significant differences in RMS(P<0.05).Among the peroneus longus,the i EMG and RMS of negative-heel group were significantly larger than those in the barefoot group(P<0.05)and the flat shoes group(P<0.05).(5)The effects of different heel heights on static balance ability index: in the eye opening test and eye closing test,the elliptical areas of negative-heel shoes group and flat shoes group were less than those of barefoot group(P<0.05).However,there were no statistical differences between negative-heel shoes group and flat shoes group(P>0.05).In the eye opening test period,the movement lengths of the negativeheel shoes group were significantly less than those of the barefoot group and the flat shoes group(P<0.05).On the contrary,there were no significant differences between the barefoot group and the flat shoes group(P>0.05).During the eye closing test period,there were no significant differences among the three groups(P>0.05).In the eyes opening state,the standard deviations of anterior to posterior in the negative-heel shoes group were less than those of the barefoot group(P<0.05).However,there were no significant differences between the negativeheel shoes group and the flat shoes group(P>0.05).In the eyes closing period,there were no significant differences in the standard deviations of anterior to posterior between the negative-heel shoes group and the flat shoes group(P>0.05).Both of them were less than the barefoot group(P<0.05).There were no significant differences in the transverse standard deviation among the groups in the opening and closing eyes tests(P>0.05).Conclusions:(1)The negative-heel shoes were more stable than the flat shoes and barefoot,but they tended to withstand greater GRF during the swing phase in a gait cycle.(2)The stability in sagittal plane of the ankle joint was increased by the negative-heel shoes in walking.Besides,the activation level of the main muscles of the lower extremity was larger.However,but the stability of the negative-heel shoes was less than that of the flat shoes during the single stance phase.(3)The negative-heel shoes were beneficial to improve the ability of static balance and the ankle control strategy,which can be used as a static balance training method. |
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