Effect of muscle action, load and velocity variation on the bilateral neuromuscular response

The purpose of this study was to assess the neuromuscular asymmetry of the medial and lateral gastrocnemius (MG, LG) and soleus (SOL) of the dominant and non-dominant limbs during different muscle actions via electromyography (EMG). Fifteen active male participants completed isometric and isotonic (maximum, submaximum, bodyweight), isokinetic (1.05 rad·s^-1, 1.31 rad·s^-1, and 1.83 rad·s^-1), squat jump, and 20 m sprint conditions on the same day. Bilateral asymmetry was only observed in the isokinetic (6.8% to 10.8%) and the squat jump (6.0% to 15.5%) conditions for the SOL, MG, and LG (P≤0.05). No relationship was found between magnitude of bilateral asymmetry and load levels. Isometric max (0.4% to 4.2%) and isometric bodyweight conditions (0.6% to 4.2%) showed the lowest bilateral asymmetry ranges across all muscles. Understanding of bilateral asymmetry induced by different muscle actions is important to prevent muscle imbalance and to understand the potential mechanisms of muscular recruitment in tasks.