The Relationship between Strength and Flexibility in Powerlifters
Spence, Alyssa-Joy Danielle
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Powerlifting is a strength sport comprised of the squat, bench press, and deadlift. To win, powerlifters must accumulate the greatest total, which is the sum of their heaviest successful attempts in the competition lifts. The addition of chronic stretching to powerlifting training may be beneficial for several reasons. Firstly, the squat and bench press are slow stretch-shortening cycle (SSC) movements, which may benefit from a more compliant musculotendinous unit. Secondly, male powerlifters have less range of motion (ROM) on average than sedentary men about the shoulder, hip, and knee. Finally, the areas with less ROM correspond with common areas of injury in powerlifters. While stretching may be beneficial to improve SSC performance and increase ROM, the stretching practices of powerlifters are unknown, and it is unclear if there is an optimal ROM for powerlifting. Therefore, the aim of this thesis was to investigate the relationship between strength and flexibility in powerlifters. Several investigations were undertaken to examine this relationship. Firstly, a survey was implemented with the purpose of identifying the prevalence and characteristics of stretching practices among powerlifters. Over 300 powerlifters from around the world participated and the main findings from this study were that irrespective of sex or competitive level approximately 50% of powerlifters reported participating in regular stretching. Of those who reported stretching, 78% stretched before training and 84% engaged in static stretching, while only 44% stretched after training. Following this, two cross-sectional studies were employed to determine active single-joint ROM in female and male powerlifters, respectively, compared with recreationally strength-trained controls, and to determine if single-joint ROM could be used to predict strength levels in powerlifters. Interestingly, female powerlifters did not have less ROM than recreationally trained women, and ROM was not a predictor for strength in female powerlifters. Whereas male powerlifters had less ROM in several movements about the shoulder (extension and horizontal abduction) and hip (flexion, extension, and adduction) than recreationally strength-trained men, and several movements (shoulder extension and horizontal abduction, hip flexion and extension) were useful to predict strength. The last series of studies were implemented to investigate the effects of chronic post-training stretching on powerlifting performance, to examine mechanisms that might contribute to changes in performance, and to observe ROM responses to strength training in the absence of stretching. The main finding of the first case study was that ROM did not increase following eight weeks of stretching and it was concluded that stretching programmes like the one implemented may not be sufficient to improve ROM in more flexible strength-trained individuals. Two more case studies were undertaken and included strength-trained men with ROM similar to male powerlifters. Both stretching and strength-training increased ROM; however, stretching was more effective than resistance training. Strength improved in the squat and bench press for both participants irrespective of the area targeted by the stretching intervention. Additionally, there were no clear patterns connecting potential mechanisms to strength or ROM changes. Further research is needed to investigate the effects of chronic post-training stretching on powerlifting performance.