Dynamic Balance and Muscle Activity in Lifesavers: A Study on Intrinsic and Extrinsic Foot Muscles

Activities on sandy soil are known to contribute to improved leg strength and balance. Lifesavers (LSs) have shown that sandy soil activity promotes intrinsic foot muscle development and improves balance. LS improves leg strength and balance through activities on sandy soil. However, the effect of foot muscle development on the actual muscle activity of LS remains unclear. We aimed to evaluate the effect of foot muscle development on muscle activity in lifeguards on a sandy beach compared with the corresponding in healthy participants. Fifteen LSs and 15 healthy adults underwent a Y-balance test to assess dynamic balance and surface electromyography to measure muscle activity. The LSs exhibited a significantly higher percentage of maximum voluntary contraction values in the tibialis anterior muscle in all directions than the healthy adults. The LSs showed increased peroneus longus and abductor hallucis muscle activity in the posterolateral and posteromedial directions, suggesting their involvement in contralateral postural control during dynamic balance. These findings suggest that engaging in barefoot activities on sandy soil enhances foot muscle activity and improves dynamic balance in LSs.