title: Impact of the Nordic hamstring and hip extension exercises on hamstring architecture and morphology: implications for injury prevention.
abstract: BACKGROUND
  The architectural and morphological adaptations of the hamstrings in response to training with different exercises have not been explored.
  
  
  OBJECTIVE
  To evaluate changes in biceps femoris long head (BFLH) fascicle length and hamstring muscle size following 10-weeks of Nordic hamstring exercise (NHE) or hip extension (HE) training.
  
  
  METHODS
  30 recreationally active male athletes (age, 22.0±3.6 years; height, 180.4±7 cm; weight, 80.8±11.1 kg) were allocated to 1 of 3 groups: (1) HE training (n=10), NHE training (n=10), or no training (control, CON) (n=10). BFLHfascicle length was assessed before, during (Week 5) and after the intervention with a two-dimensional ultrasound. Hamstring muscle size was determined before and after training via MRI.
  
  
  RESULTS
  Compared withbaseline, BFLHfascicles were lengthened in the NHE and HE groups atmid-training(d=1.12-1.39, p<0.001) andpost-training(d=1.77-2.17, p<0.001) and these changes did not differ significantly between exercises (d=0.49-0.80, p=0.279-0.976). BFLHvolume increased more for the HE than the NHE (d=1.03, p=0.037) and CON (d=2.24, p<0.001) groups. Compared with the CON group, both exercises induced significant increases in semitendinosus volume (d=2.16-2.50, ≤0.002) and these increases were not significantly different (d=0.69, p=0.239).
  
  
  CONCLUSIONS
  NHE and HE training both stimulate significant increases in BFLHfascicle length; however, HE training may be more effective for promoting hypertrophy in the BFLH.
authors.affiliation: Department of Rehabilitation, Nutrition and Sport, La Trobe Sport and Exercise Medicine Research Centre, Melbourne, Victoria, Australia.|Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia.|Queensland Academy of Sport, Centre of Excellence for Applied Sport Science Research, Brisbane, Queensland, Australia.
authors.forename: Matthew N
authors.initials: MN
authors.lastname: Bourne
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia.|Faculty of Health, School of Exercise and Nutrition Science, Queensland University of Technology, Brisbane, Queensland, Australia.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Duhig
authors.affiliation: School of Exercise Sciences, Australian Catholic University, Melbourne, Victoria, Australia.
authors.forename: Ryan G
authors.identifier: http://orcid.org/0000-0003-4964-1848
authors.initials: RG
authors.lastname: Timmins
authors.affiliation: Faculty of Life Sciences and Education, School of Health, Sport and Professional Practice, University of South Wales, Wales, UK.
authors.forename: Morgan D
authors.initials: MD
authors.lastname: Williams
authors.affiliation: School of Exercise Sciences, Australian Catholic University, Melbourne, Victoria, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Opar
authors.affiliation: Centre for Advanced Imaging, University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Aiman
authors.initials: A
authors.lastname: Al Najjar
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia.|Faculty of Health, School of Exercise and Nutrition Science, Queensland University of Technology, Brisbane, Queensland, Australia.
authors.forename: Graham K
authors.initials: GK
authors.lastname: Kerr
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia.|Faculty of Health, School of Exercise and Nutrition Science, Queensland University of Technology, Brisbane, Queensland, Australia.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Shield
mesh_terms: D000328:Adult; D001265:Athletic Injuries / Q000517:prevention & control*; D000070633:Hamstring Muscles / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D052580:Muscle Stretching Exercises; D014463:Ultrasonography; D055815:Young Adult
keywords: Hamstrings; Injury prevention; Physiotherapy; Strength