title: Impact of back squat training intensity on strength and flexibility of hamstring muscle group.
abstract: METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Occupational Health, Faculty of Medicine and Health Sciences, University Putra Malaysia, Serdang, Selangor, Malaysia.|Department of Exercise Physiology, Faculty of Sport Sciences, University of Isfahan, Isfahan, Iran.
authors.forename: Ardalan
authors.initials: A
authors.lastname: Shariat
authors.affiliation: Department of Health and Human Performance, Cleveland State University, Cleveland, OH, USA.
authors.forename: Eddie T C
authors.initials: ETC
authors.lastname: Lam
authors.affiliation: Department of Sport and Movement Studies, University of Johannesburg, Doornfontein, Johannesburg, Republic of South Africa.
authors.forename: Brandon S
authors.initials: BS
authors.lastname: Shaw
authors.affiliation: Department of Sport and Movement Studies, University of Johannesburg, Doornfontein, Johannesburg, Republic of South Africa.
authors.forename: Ina
authors.initials: I
authors.lastname: Shaw
authors.affiliation: Department of Exercise Physiology, Faculty of Sport Sciences, University of Isfahan, Isfahan, Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Kargarfard
authors.affiliation: School of Physiotherapy, University of Otago, Dunedin, New Zealand.
authors.forename: Bahram
authors.initials: B
authors.lastname: Sangelaji
mesh_terms: D000328:Adult; D056352:Athletes; D001415:Back; D015992:Body Mass Index; D000070633:Hamstring Muscles / Q000502:physiology*; D006801:Humans; D035002:Lower Extremity; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D055070:Resistance Training / Q000379:methods*; D055815:Young Adult
keywords: High-intensity; injury; maximum strength; multi-joint; resistance training