Ankle strategies for step-aside movement during quiet standing

Abstract

The mediolateral ankle strategy plays a crucial role in providing ankle stability in ground obstacle-avoidance behavior. This is achieved by changing basic walking patterns according to the characteristics of the obstacle. In daily life, it is more common to use step-aside movement (i.e., dodging step) for collision avoidance rather than side-stepping (i.e., widening standing base) when encountering an approaching pedestrian or bicycle. While studies have been conducted on the mediolateral ankle strategy contribution in obstacle avoidance using side-stepping, knowledge of step-aside movement is still inadequate. Therefore, we conducted an electromyography (EMG) analysis on the tibialis anterior (TA), peroneus longus (PL), and soleus (SOL) muscles, as well as measured center of pressure (CoP) displacement, and vertical ground reaction force (vGRF) of the standing leg, in order to understand the role of ankle muscles in step-aside movement during quiet standing. Fifteen healthy young men repeated twelve step-aside movements in both left and right directions. A Bayesian one-sample t-test was used to determine the sufficient step and participant counts. Multiple linear regression analysis was used to investigate the correlation between the muscle activity and CoP displacement or vGRF. The regression coefficients (β) of the left push phase and the right loading phase were tested against zero using a Bayesian one-sample t-test to identify the correlation between independent and dependent variables. We used the one-dimensional statistical parametric mapping (SPM1d) method to analyze the differences between and within the groups of EMG data based on the continuous time series. The results showed that the PL displayed a substantial contribution to the mediolateral ankle strategy during the push phase of step-aside movement, and also contributed to maintaining ankle stability during the loading phase. This suggested that screening for PL weakness and providing appropriate interventions and/or training approaches is especially critical for populations with walking stability problems.

Ankle Strategies for Step-Aside Movement during Straight Walking

“…Multiple linear regression analyses were performed for the left CoP (left CoPx, left CoPy) and left GRF (left F-GRF) models. PL contraction dominated the mediolateral ankle strategy in step-aside movements ( Table 1 ), which aligns with our previous findings [ 1 ]. F-GRF generation was strongly correlated with independent variables in the left push phase for both movements, indicating that the combination of ankle muscle contraction and CoP displacement significantly influenced F-GRF generation.…”

“…Our results reveal significantly higher bilateral ankle muscle activation during step-aside movement than during straight walking in the selected period of the left push phase, particularly in the left PL muscle, as previously reported [ 1 ]. The results support our hypothesis that the CoP trajectories in the left push phase within the selected ROI would significantly differ.…”

“…Step-aside movement (dodging step) during walking is a common maneuver to avoid obstacles; however, it is associated with fall risk owing to differences in neural control mechanisms and ankle strategies compared to straight walking. In our previous study, the mechanisms of ankle muscle contraction, foot center of pressure (CoP) displacement, and ground reaction force (GRF) generation in step-aside movements during standing were explored, excluding the influence of walking [ 1 ]. The current study aimed to extend previous findings by studying these mechanisms during straight walking, offering potential avenues for understanding obstacle avoidance.…”

“…Building on a previous study, which demonstrated the crucial role of the PL in the push and loading phases of step-aside movement and the substantial contribution of the TA to toe clearance in the push phase [ 1 ], we hypothesized that: The PL would exhibit the greatest contraction during the left push phase of the step-aside movement, and all three ankle muscles would show increased contractions in the right loading phase compared to straight walking. The TA would have the most significant contraction to achieve left-toe clearance.…”

Trend change analysis in the assessment of body balance during posture adjustment in reaction to anterior-posterior ground perturbation

“…Research conducted by Xie et al . [ 4 , 5 ], revealed that PAs may result from the internal initiation of movement (preparation to perform a certain activity). Similarly, Cleworth et al .…”