Modulation of Free Radical – Scavenging Pathways in Response Passive Stretch Training in Mice

Abstract

• Muscle injury generated by lengthening contractions has damaging effects including pain, muscle weakness, and decreased range of motion in patients ranging from athletes to the elderly. • Training with various types of exercise (passive stretch, isometric contractions, and prior training with lengthening contractions) has been shown to protect skeletal muscle from such injury. • Passive stretch training is of particular interest because it provides protection to skeletal muscle in adult and elderly mice and is non-damaging. • Recent research has revealed that reactive oxygen species are produced by skeletal muscle during non-damaging contractions as well as during damaging contractile activity, suggesting that free radicals may play some role in the induction of adaptive responses to contractile activity. • We hypothesized that passive stretch training protects skeletal muscle from lengthening contraction-induced muscle injury through endogenous modifications in free radical scavenging pathways, particularly via increases in activities of two key antioxidant enzymes, superoxide dismutase (SOD) and catalase. • Thus, our goal was to determine whether administering a protocol of passive stretches known to provide protection from subsequent lengthening contractioninduced muscle injury resulted in increased SOD and catalase activity levels.