Affiliations: [a] Department of Occupational Health, Faculty of Medicine and Health Sciences, University Putra Malaysia, Serdang, Selangor, Malaysia | [b] Department of Exercise Physiology, Faculty of Sport Sciences, University of Isfahan, Isfahan, Iran | [c] Department of Health and Human Performance, Cleveland State University, Cleveland, OH, USA | [d] Department of Sport and Movement Studies, University of Johannesburg, Doornfontein, Johannesburg, Republic of South Africa | [e] School of Physiotherapy, University of Otago, Dunedin, New Zealand
Correspondence:
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Corresponding author: Mehdi Kargarfard, Department of Exercise Physiology, Faculty of Sport Sciences, University of Isfahan, Isfahan, Iran. E-mail:m.kargarfard@spr.ui.ac.ir
Abstract: STUDY DESIGN: True experimental design. BACKGROUND: The back squat is an integral aspect of any resistance training
program to improve athletic performance. It is also used for injury
prevention of the lower limbs. OBJECTIVE: The purpose of this study was to
examine the effect of back squat training at different intensities on
strength and flexibility of the hamstring muscle group (HMG). METHODS: Twenty-two male recreational bodybuilders with at least two years of
experience in resistance training were recruited to participate in a
nine-week training program. They were randomly assigned to a heavy back
squat group (90-95% of one repetition maximum) or a moderate-intensity
back squat group (60-65% of one repetition maximum). RESULTS: The heavy back squat group resulted in a significantly (p < 0.001)
increased in one repetition maximum strength but a significant (p < 0.001)
reduction in HMG flexibility when compared to their counterparts. The
results of the study indicate that while a heavy back squat training program
is effective in improving strength, it has an adverse effect on the
flexibility of the HMG. CONCLUSION: The implication of this study is that there is a tradeoff
between strength and flexibility and trainers should select the appropriate
training protocols for their athletes to maximize athletic performance.
Keywords: High-intensity, injury, resistance training, maximum strength, multi-joint
