# Faster Club Hockey Athletes Have Reduced Upper Leg Muscular Co-contraction During Maximal-Speed Sprinting

## TL;DR

Faster hockey athletes show less muscle co-contraction in their upper legs during sprinting, which may help them run faster.

## Contribution

This study provides novel insights into muscle coordination patterns during sprinting in collegiate athletes.

## Key findings

- Faster athletes had lower co-contraction index (CCI) in rectus femoris and biceps femoris.
- Reduced CCI was observed during the late swing phase of sprinting.
- Findings suggest coordination between these muscles is linked to sprinting velocity.

## Abstract

Most electromyographic (EMG) data for muscular activation patterns during ambulation is limited to older adults with existing chronic disease(s) walking at slow velocities. However, we know much less about the lower extremity muscle co-contraction patterns during sprinting and its relation to running velocity (i.e., performance). Therefore, we compared lower extremity muscular activation patterns during sprinting between slower and faster collegiate club hockey athletes. We hypothesized that faster athletes would have lower EMG-assessed co-contraction index (CCI) values in the lower extremities during over-ground sprinting.

Twenty-two males (age = 21[1] yrs (median[IQR]); body mass = 77.1 ± 8.6 kg (mean ± SD)) completed two 20-m over-ground sprints with concomitant EMG and asynchronous force plate testing. We split participants using median running velocity (FAST: 8.5 ± 0.3 vs. SLOW: 7.7 ± 0.3

m/s, p < 0.001). Faster athletes had lower CCI between the rectus femoris and biceps femoris (group: p = 0.05), particularly during the late swing phase of the gait cycle (post hoc p = 0.02). In agreement with our hypothesis, we found lower CCI values in the upper leg musculature during maximal-speed over-ground sprinting. These data from collegiate club hockey athletes corroborate other reports in clinical populations that the coordination between the rectus femoris and biceps femoris is associated with linear over-ground sprinting velocity.