Author(s): YOKOTA, K., YOSHIHIRO, N.1, AYUMU, U.1, HIROYUKI, T.2, Institution: NATIONAL INSTITUTE OF FITNESS AND SPORTS, Country: JAPAN, Abstract-ID: 2066

INTRODUCTION:
Moment-to-moment changes in agonist and antagonist muscle activity during sprint running can be evaluated using surface electromyography (sEMG). Lissajous figures provide a means of visualizing these activity patterns, while the cross-correlation function (CCF) quantifies their temporal relationships. This study aims to evaluate antagonistic bi-articular thigh muscle activity patterns during sprint running using these techniques.
METHODS:
Forty male track and field athletes performed maximal effort sprint running over 50m. During this test, sEMG signals were recorded from the rectus femoris (RF) and biceps femoris (BF) and ground reaction force (GRF) data were collected using a 50m force plate system, which recorded 25 steps. Sprint cycles were defined based on GRF data, with one cycle (1Cycle) from ipsilateral toe-off to foot-strike. The CCF R-values (≥ 0) were used as an index of similarity, and the mean R-value at zero time lag was calculated for each 1Cycle1. Participants were then categorized into two groups based on their CCF R-values using the mean ± 1 SD as the threshold: those with R-values above this range were classified as the High-group, and those below this range were classified as the Low-group. Lissajous figures were examined to characterize differences in muscle activation patterns between the groups.
RESULTS:
The mean CCF R-value across all participants was 0.656. The High-group exhibited R-values ranging from 0.732 to 0.848, whereas the Low-group showed R-values between 0.345 to 0.540. The Lissajous figures of the High-group displayed an irregular spiral shape, suggesting greater coactivation of RF and BF, whereas the Low-group exhibited a reciprocal activation pattern between RF and BF.
CONCLUSION:
This study applies established methods to quantify and visualize antagonistic bi-articular thigh muscle activity specifically during sprint running. The observed differences in coactivation and reciprocal activation patterns suggest potential variations in neuromuscular control strategies among sprinters. These findings may aid in developing training approaches to optimize sprint-related muscle activation patterns.
REFERENCE:
1 Tishya et al., (2006), Journal of Biomechanics 39, 2714:2718