60-Second Static Stretching of Lower Limb Muscles Disrupts Muscular Performance and Control in Active Male Adults

This study aimed to investigate the effects of 60-second static stretching on the neuromuscular control strategies of lower limb muscles during a squat jump (SJ), with a specific focus on changes in muscle synergy patterns, muscle weightings, and temporal activation characteristics. The muscles targeted for stretching included the quadriceps, hamstrings, and triceps surae. Electromyography (EMG) was used to assess the activity of the biceps femoris (BFL), triceps surae(TS), rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM). Twenty-five active males completed experiments under both a static stretching condition (SS) and a non-stretching condition (NS). Electromyography and non-negative matrix factorization (NMF) were employed to extract muscle synergy and the muscle weightings along with temporal activation characteristics were subsequently analyzed. The results revealed two distinct muscle synergy patterns in both the SS and NS. 60-second static stretching had no significant impact on the number of muscle synergy patterns during the squat jump. However, it significantly altered the contribution and temporal activation characteristics of individual muscles. Notably, post-stretching muscle activation levels were lower during the early phase of the jump, necessitating compensatory activation in the later phase to maintain performance. Additionally, jump heights were significantly lower in the stretched compared to the non-stretched condition.These findings suggest that while 60 seconds of static stretching before explosive movements may impair neuromuscular efficiency, ensuring proper and balanced static stretching for all muscle groups could help mitigate over-reliance on individual muscles.