# Asymmetry in Muscle Activation and Co-Contraction Between Lower Limb During Zap-3 Flamenco Footwork

## TL;DR

This study examines muscle activation asymmetries in professional and amateur flamenco dancers during Zap-3 footwork at different speeds.

## Contribution

The study reveals speed-dependent muscle asymmetries in professional dancers during Zap-3 footwork.

## Key findings

- Professionals showed significant asymmetry in gastrocnemius medialis and biceps femoris activation at the fastest speed.
- Higher co-contraction index was observed in dominant legs of professionals at maximum speed.
- Asymmetries were not observed in amateur dancers or at lower speeds.

## Abstract

This study aims to investigate asymmetries in muscle activation and co-contraction of main lower limb muscles during flamenco Zap-3 footwork with consideration of the footwork speed and dancer proficiency. Twelve flamenco dancers participated, including six professionals and six amateurs. Each participant performed the Zap-3 sequence under three speed conditions: 160 beats per minute (bpm), 180 bpm and the fastest speed level (F). The normalized surface electromyography was recorded in the gastrocnemius medialis (GM), biceps femoris (BF), tibialis anterior (TA) and rectus femoris (RF) in the dominant (DL) and non-dominant leg (NDL). The co-contraction index was also calculated for selected muscle pairs. The results showed that significant asymmetries occurred only in professional dancers and exclusively at the F speed level. Specifically, the value of the GM in the NDL was higher than that of the DL (p < 0.05, d = 1.97); the value of the BF in the DL was higher than that of the NDL (p < 0.05, d = 1.86) and the co-contraction index of BF/RF in the DL was higher than that of the NDL (p < 0.05, d = 1.87). Understanding these asymmetries may help to inform individualized training strategies aimed at optimizing performance and reducing potential risks.