Background The architectural and morphological adaptations of the hamstrings in response to training with different exercises have not been explored.
Purpose 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). BFLH fascicle 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 with baseline, BFLH fascicles were lengthened in the NHE and HE groups at mid-training (d=1.12–1.39, p<0.001) and post-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). BFLH volume 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).
Conclusion NHE and HE training both stimulate significant increases in BFLH fascicle length; however, HE training may be more effective for promoting hypertrophy in the BFLH.
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Contributors MNB was the principle investigator and was involved with study design, recruitment, analysis and manuscript write up. SJD and RGT were involved in data collection. MDW, DAO, GKK and AJS were involved with the study design, analysis and manuscript preparation. AAN was involved in MRI data acquisition. All the authors had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis.
Funding This study was funded by the Queensland Academy of Sport's Centre of Excellence for Applied Sports Science Research.
Competing interests None declared.
Patient consent Obtained.
Ethics approval The study was approved by the Queensland University of Technology Human Research Ethics Committee and the University of Queensland Medical Research Ethics Committee.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement The authors are happy to share data.
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