Reduced strength after passive stretch of the human plantarflexors

Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada L8S 4K1 The purpose of this study was to assess strength performance after an acute bout of maximally tolerable passive stretch (PS max ) in human subjects. Ten young adults (6 men and 4 women) underwent 30 min of cyclical PS max (13 stretches of 135 s each over 33 min) and a similar control period (Con) of no stretch of the ankle plantarflexors. Measures of isometric strength (maximal voluntary contraction), with twitch interpolation and electromyography, and twitch characteristics were assessed before (Pre), immediately after (Post), and at 5, 15, 30, 45, and 60 min after PS max or Con. Compared with Pre, maximal voluntary contraction was decreased at Post (28%) and at 5 (21%), 15 (13%), 30 (12%), 45 (10%), and 60 (9%) min after PS max ( P