The effects of antagonist stretching on agonist performance

Introduction The idea of stretching the antagonist muscle to enhance the performance of the agonist muscle has gained considerable attention in recent years. However, most studies have focused on a single stretching duration, leaving a gap in research that compares the effects of varying stretching durations on agonist muscle performance. Purpose The aim of this study was to compare different durations (40-, 80-, and 120-seconds as well as a control condition) of antagonist static stretching (SS) on agonist muscle performance. Methods In this randomized crossover study, 16 participants (six females) who do strength training sessions 2-3 times per week regularly were recruited. The study aimed to investigate the acute effects of tibialis anterior (TA) SS with different durations on the plantar flexion (PF) performance and soleus activation. The participants underwent four sessions, with 24-72 hours interval between sessions. Each session included testing pre- and post-SS and one session for control condition without SS. Measurements included the dominant leg’s slow (60 degrees/s) and fast (240 degrees/s) PF isokinetic peak torque, isometric peak torque, total work, stiff leg drop jump (SDJ) performance including height, reactive strength index (RSI) and peak power, and finally, electromyography (EMG) from TA and soleus. TA SS protocol involved 1x40 (40s), 2x40 (80s), and 3x40s (120s) with 15-seconds rest in between sets. Results There were no significant effects of specific antagonist stretching durations on changes in pre- to post-intervention isometric peak torque, slow or fast isokinetic peak torque, total work, or SDJ height, RSI, and peak power (p > 0.05). However, when combining all stretch durations and the control condition (main effect for time), there was a general decrease in fast and slow isokinetic peak torque, total work, and all SDJ measures (p < 0.05). Soleus EMG decreased from pre- to post-SS significantly after 120s in both isometric (p = 0.002) and slow isokinetic (p = 0.002) peak torque as well as 80s in slow isokinetic peak torque (p = 0.02). Conclusions The main finding of this study was different durations of antagonist stretching (40s, 80s, 120s) did not significantly influence the agonist muscles performance. However, when all stretch durations and control conditions were combined, a general decrease was observed in fast and slow isokinetic peak torque, total work, and all SDJ measures, indicating possible testing effects.