Hindawi Publishing Corporation Journal of Sports Medicine Volume 2013, Article ID 481490, 7 pages http://dx.doi.org/10.1155/2013/481490 Research Article The Acute Effects of Upper Extremity Stretching on Throwing Velocity in Baseball Throwers Michael Williams, Lanisa Harveson, Jason Melton, Ashley Delobel, and Emilio J. Puentedura Department of Physical herapy, School of Allied Health Sciences, University of Nevada Las Vegas, 4505 Maryland Parkway, P.O. Box 453029, Las Vegas, NV 89154-3029, USA Correspondence should be addressed to Emilio J. Puentedura; louie.puentedura@unlv.edu Received 29 June 2013; Revised 31 August 2013; Accepted 19 September 2013 Academic Editor: Mark Willems Copyright © 2013 Michael Williams et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Purpose. To examine the efects of static and proprioceptive neuromuscular facilitation (PNF) stretching of the shoulder internal rotators on throwing velocity. Subjects. 27 male throwers (mean age = 25.1 years old, SD = 2.4) with adequate knowledge of demonstrable throwing mechanics. Study Design. Randomized crossover trial with repeated measures. Methods. Subjects warmed up, threw 10 pitches at their maximum velocity, were randomly assigned to 1 of 3 stretching protocols (static, PNF, or no stretch), and then repeated their 10 pitches. Velocities were recorded ater each pitch and average and peak velocities were recorded ater each session. Results. Data were analyzed using a 3×2 repeated measures ANOVA. No signiicant interaction between stretching and throwing velocity was observed. Main efects for time were not statistically signiicant. Main efects for the stretching groups were statistically signiicant. Discussion. Results suggest that stretching of the shoulder internal rotators did not signiicantly afect throwing velocity immediately ater stretching. his may be due to the complexity of the throwing task. Conclusions. Stretching may be included in a thrower’s warm-up without any efects on throwing velocity. Further research should be performed using a population with more throwing experience and skill. 1. Introduction Baseball throwers commonly use stretching to prepare for and improve throwing performance. Performance can be measured in several ways, but one of the most common mea- sures for throwers is throwing velocity. Stretching has long been associated with a typical warm-up for most athletes. Beneits from stretching are thought to include increased range of motion (ROM) and increased lexibility [1]. he neu- romuscular mechanisms that may be associated with these efects include relex inhibition of the Golgi tendon organ and lengthening of the musculotendinous unit [1] which ulti- mately is believed to increase overall performance in a desired sport or activity, including throwing. However, research has consistently shown that in lower extremity activities that rely on quick bursts of power stretching negatively afects muscle strength and power output immediately ater the stretch [2– 4]. Researchers have suggested that the observed decrease in power output is most likely due to a decrease in stifness of the musculotendinous unit. his results in a decreased ability of the muscle to generate force [2]. Less research has been conducted investigating whether these efects would also be observed in the upper extremity. One study, conducted by Haag et al. [5], analyzed the efects of an upper extremity stretching protocol on throw- ing velocity. heir stretching protocol consisted of 6 static stretches performed in the directions of horizontal adduc- tion, horizontal abduction, external rotation, internal rota- tion, lexion, and extension. he muscles involved in these motions were chosen because they are active in at least one point of the throwing motion. When compared to the control group, which consisted of a team warm-up without stretching, no diference in throwing velocity was found [5]. heir study focused on increasing the overall ROM of the shoulder. However, based upon results from electromyo- graphy (EMG) studies, the shoulder internal rotators are