Resistance Training vs. Static Stretching: Effects on Flexibility and Strength

Morton SK, Whitehead JR, Brinkert RH, Caine DJ.  Journal of Strength and Conditioning Research.  2011 Sept 30

It is important for both athletes and non-athletes to have adequate range of motion (ROM) in their muscle-joint complexes.  Long-standing beliefs of how static stretching and resistance training affect strength and flexibility are now being challenged by recent research.  The purpose of this study was to determine how full-range resistance training affected flexibility and strength compared to static-stretching of the same muscle-joint complexes in untrained adults. The authors posit that static-stretching increases flexibility compared to control, but those gains would not be superior to resistance training.  The study design included a five-week intervention with pre- and post-strength and flexibility testing of hamstring extension, hip flexion and extension, shoulder extension flexibility, and peak torque of quadriceps and hamstring muscles.  Volunteers were randomized to a resistance-training group or static stretching group.  Subjects then performed 5 weeks of either strength training or static stretching.  The enrolled subjects were provided supervised training in their chosen group.  The control group consisted of inactive volunteers.  No difference was found between the 2 intervention groups in hamstring flexibility, hip flexion, and hip extension, but both groups demonstrated superior ROM gains compared to controls.  The resistance-training group had improved knee extension peak torque compared to controls.  There were no differences found between any of the groups with shoulder extension flexibility and knee flexion peak torque. 

Most athletes are involved in an exercise program with goals of improving their performance and preventing injury.  Weight training and stretching are two important components of this.  Proper stretching is usually emphasized before, during, and after resistance training to maintain flexibility.  The results they obtained supported their hypothesis that resistance training does not decrease flexibility.  The authors recognize the limitations of this small, pilot study and acknowledge it in their discussion.  One other possible limitation of the study is the type of weight-training used.  Athletes use a variety of regimens, varying the number of repetitions in each set and the amount of weight used to match their goals for their specific sport.   It would be interesting to see if a lower repetition workout with higher weights would give the same results as a higher repetition, lower weight workout that was likely used in this study.  In this study design, these athletes were instructed and observed to ensure that they maintained full range of motion throughout all exercises in the resistance-training regimen.  Most athletes do not have constant monitoring during their workouts to ensure proper form.  If these findings are consistently replicated in future studies, it might change our clinical recommendations regarding the type of exercise required to maintain flexibility.  It would also be interesting to study the combination of strength training and static stretching since this is common practice for all athletes.  I agree with the authors that further studies are needed to make any change in recommendations at this time.  How do you view and/or instruct stretching with your athletes?  Do you feel resistance training can increase flexibility without any stretch or soft tissue mobilizations? 

Written by: Kris Fayock, MD & Marc I. Harwood, MD
Reviewed by: Stephen Thomas

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Morton SK, Whitehead JR, Brinkert RH, & Caine DJ (2011). Resistance Training vs. Static Stretching: Effects on Flexibility and Strength. Journal of Strength and Conditioning Research PMID: 21969080