# Differences in left and right lower limb control strategies in coping with visual tracking tasks during bipedal standing

## TL;DR

This study found that the right lower limb is better at tracking visual targets during balance tasks compared to the left.

## Contribution

The study reveals novel insights into asymmetrical lower limb control strategies during visual tracking.

## Key findings

- The right lower limb showed significantly better tracking ability in the anterior-posterior direction for both predictable and random visual tasks.
- No significant difference was found between the lower limbs in the medio-lateral direction during tracking.
- The right limb's enhanced tracking suggests a potential role in balance control based on visual stimuli.

## Abstract

Differences in motor control between the lower limbs may influence the risk of sports injury and recovery from rehabilitation. In this study, differences in the visual feedback ability of the left and right lower limbs were assessed using visual target tracking tasks.

Thirty-four healthy young subjects (aged 20.4 ± 1.2 years) were asked to move their bodies back and forth while tracking a visual target displayed on a monitor in front of them for 30 s. The two target motions were sinusoidal (i.e., predictable patterns) and more complex (random) patterns. To assess the ability of the lower limbs to follow visual target tracking, antero-posterior CoP (right limb, CoPap–r; left limb, CoPap–l) and medio-lateral CoP (right limb, CoPml–r; left limb, CoPml–l) data were measured using a stabilometer. Tracking ability by visual feedback ability was calculated as the difference in displacement between the target signal and the trajectories of the right and left pressure centers as trapezoidal areas, and a smaller sum of area (SoA) over the entire measurement time was defined as a greater tracking ability.

Regarding the SoA in the anterior-posterior CoP, the mean SoA in the sinusoidal and random tasks was significantly lower in the CoP-r data than in the CoP-l data, indicating that the right lower limb had a more remarkable ability to follow visual target tracking. Regarding the SoA in the medial-lateral direction (CoP), the mean SoA in the sinusoidal and random tasks did not significantly differ between the two legs.

The right lower limb may have a tracking function activated by the target signal when responding to visual stimuli. Identifying the motor strategies of each lower limb in response to visual stimuli will not only help identify potential differences between each lower limb but also suggest the possibility of enhancing the role of each lower limb in balance control.