The Effect of Dominant Side Leg Exercise in Different Environments with and without Resistance on Non-Dominant Leg Muscle Activation: Sitting Position

Objective: This study aimed to investigate the effects of dominant-side resistance exercise on the muscle activity of the non-dominant side according to the exercise condition, and to propose more effective exercise methods for improving the muscle strength imbalance between the dominant and non-dominant legs. Design: A cross-sectional study Methods: Twenty-one healthy adults aged 20–30 participated in this study. There were 10 males and 11 females, with an average height of 170.35 cm and weight of 66.7 kg. Each participant performed eight exercises: Leg, resistance leg, non-surface leg, non-surface resistance leg, visual block leg, visual block resistance leg, ankle support leg, and ankle support resistance leg exercises. The exercise order was randomized. Surface electromyography was used to measure the activation of the rectus femoris, vastus medialis oblique, vastus lateralis, tibialis anterior, gastrocnemius, and biceps femoris muscles in the non-dominant leg during dominant leg exercises. Average values of three measurements were considered as the final results. Results: Rectus femoris, vastus medialis oblique, vastus lateralis, tibialis anterior, and biceps femoris muscles showed the highest activation during visual block resistance leg exercise, whereas gastrocnemius muscles exhibited the highest activation during ankle support resistance leg exercise (p<0.05). Therefore, muscle activation varied depending on the resistance level and exercise type. Conclusions: Overall, this study demonstrated that resistance level and exercise type significantly influenced the non-dominant leg muscle activation. Our results provide foundational data for the development of balanced training and rehabilitation programs to improve the lower limb strength.