Effects of static and dynamic stretching on upper limb explosive, isometric and endurance strength, in male volleyball players

The purpose of this study was to investigate the acute effects of both static and dynamic stretching on upper limb strength and to assess whether a cross-over inhibitory effect occurred during the time in which this effect may appear. Eighteen male volleyball players (aged 21.50, standard deviation 3.12 years) underwent the experimental protocol organized in two sessions, one of static and the other of dynamic stretching for upper body muscles. Participants performed three specific strength tests: Ball Throwing, Maximum Voluntary Isometric Contraction, and Push-Up, to assess explosive, isometric and endurance strength respectively, at baseline (T0) and 10, 20 and 60 minutes after the static stretching and dynamic stretching sessions. The Ball Throwing results showed significant differences between the two stretching protocols (F1,14 = 4.967; p = 0.043; ηp2 = 0.262), among the 5 time measures (F4,58 = 7.476; p < 0.001; ηp2 = 0.348), and for the interaction Protocol × Time (F4,58= 8.258; p < 0.001; ηp2 = 0.371). Maximum Voluntary Isometric Ccontraction scores showed significant differences among the time measures (F4,58 = 4.015; p = 0.006; ηp2 = 0.223) and for the interaction Session × Time (F4,58 = 2.625; p = 0.044; ηp2 = 0.158). At the Push-Up test significant differences were found only among the time measures (F4,58 = 5.634; p = 0.001; ηp2 = 0.287). Static stretching may adversely affect upper limb endurance strength, whereas no changes in isometric and explosive strength were found. Dynamic stretching did not have a detrimental effect on upper limb endurance strength, whereas it may improve isometric and explosive strength.