907 International Journal of Sport Studies. Vol., 4 (8), 907-913, 2014 Available online at http: www.ijssjournal.com ISSN 2251-7502 © 2014; Science Research Publications Acute effect of different warm-up stretch protocols on vertical jump performance in volleyball players Rouhollah Haghshenas (PhD) 1* , Iman Taleb-Beydokhti (MSc) 2 , Sayyed Mohsen Avandi 3 1- Assistant Professor of exercise physiology, Department of Human Science, Semnan University, Semnan, Iran 2- Group of physical education, Department of Human Science, Semnan University, Semnan, Iran 3- Ph.D., Assistant Professor of exercise physiology, Department of Human Science, Semnan University, Semnan, Iran *Corresponding Author, Email: rhm@profs.semnan.ac.ir Abstract The purpose of this study was to examine the acute effects of different stretching protocols on power in volleyball players. Thirty-two female volleyball players (age: 20.41±5.94 years old, weight: 65.06±11.45 kg, height:180.16±7.00 cm and volleyball training experience: 5.09±4.08 years) performed 4 different warm-up protocols in randomly assigned order: (a) no stretching, (b) static stretching, (c) dynamic stretching, and (d) combined stretching. The results analyzed using ANOVA showed that There was a significant increase in power after dynamic stretching (49.09±7.04) vs. Static stretching (47.37±7.08) at p<0.004, but there were no significant differences among dynamic stretching vs. Combine (static+dynamic) stretching (48.25±6.87) at p<0.080, and combine (static+dynamic) stretching (48.25±6.87) vs. Static stretching at p<0.067. It was concluded that static stretching as part of a warm-up may decrease height jump performance, whereas dynamic stretching seems to increase height jump performance. Key words: Anaerobic power, Combine stretching, Dynamic stretching, Static stretching. Introduction The vertical jump is an explosive activity a number of athletes are required to perform in many different sports such as basketball, soccer, and volleyball. power plays a key factor in many sports, and its improvement of efficiency during training and competition can be developed with proper warm-up (Faigenbaum, McFarland et al. 2006). It is believed that the use of stretching as part of a warm-up routine may improve performance and decline the risk of injuries and postponed onset muscle soreness (Knudson and Bennett et al. 2001). However, conventional beliefs regarding the routine practice of pre-event static stretching have recently been questioned (Shrier 2004; Thacker and Gilchrist et al., 2004; Small and Naughton et al., 2008). Several studies have shown that static stretching exercises that are commonly used by athletes prior to training or competition may impair vertical jump performance (Young and Elliott 2001, Cornwell, Nelson et al. 2002, McNeal and Sands 2003, Young and Behm 2003, McMillian, Moore et al. 2006, Bradley, Olsen et al. 2007, Hough and Ross et al. 2009), but others report that static stretching has no effect at all on vertical jump(Fowles, Sale et al. 2000, Bacurau, Monteiro et al. 2009). On the other hand, the dynamic general or specific explosive movements that are typically performed during warm-up may induce a phenomenon called post-activation potentiation (PAP) that enhances muscular power and speed (Fletcher and Jones 2004, Faigenbaum, Bellucci et al. 2005, Hodgson, Docherty et al. 2005, Little and Williams 2006, Hilfiker, Hübner et al. 2007, Kilduff, Bevan et al. 2007, Needham, Morse et al. 2009, Gelen 2011, Amiri-Khorasani and Fattahi-Bafghi 2013, Kruse, Barr et al. 2013). According to previous studies, there were conflicting finding performance (Church, Wiggins et al. 2001, Knudson, BENNETT et al. 2001, Burkett, Phillips et al. 2005, Samuel, Holcomb et al. 2008). Therefore, some researchers suggested that players should not use static stretching before activities that depend of high levels of