STUDY DESIGN: Repeated-measures experi­mental design. OBJECTIVE: To examine the acute effects of static stretching on peak torque, the joint angle at peak torque, mean power output, and electromyo­graphic and mechanomyographic amplitudes and mean power frequency of the vastus lateralis and rectus femoris muscles during maximal eccentric isokinetic muscle actions. BACKGROUND: A bout of static stretching may impair muscle strength during isometric and concentric muscle actions, but it is unclear how static stretching may affect eccentric force production. METHODS AND MEASURES: Fifteen men (mean 6 SD age, 23.4 6 2.4 years) performed maximal eccentric isokinetic muscle actions of the dominant and nondominant knee extensor muscles at 60°·s–1 and 180°·s–1 on an isokinetic dynamometer, while electromyographic and mech­anomyographic amplitudes (root-mean-square) and mean power frequency were calculated for the vastus lateralis and rectus femoris muscles. Peak torque (Nm), the joint angle at peak torque (°), and mean power output (W) values were recorded by the dynamometer. Subsequently, the dominant lower extremity knee extensors underwent static stretching exercises, then the assessments were repeated. RESULTS: There were no stretching-related changes in peak torque, the joint angle at peak torque, mean power output, electromyographic or mechanomyographic amplitude, or mean power frequency (P>.05). However, there were expected velocity-related, limb-related, and muscle-related differences (P≤.05) that were unrelated to the stretching intervention. CONCLUSION: These results suggest that static stretching does not affect maximal eccentric isokinetic torque or power production, nor does it change muscle activation.  

J Orthop Sports Phys Ther. 2007;37(3):130-139. doi:10.2519/jospt.2007.2389 

KEY WORDS: EMG, muscle activation, muscle stiffness, stretching-induced force deficit