Related Experiment Video
Updated: Jan 10, 2026
Muscle Imbalances: Testing and Training Functional Eccentric Hamstring Strength in Athletic Populations
Published on: May 1, 2018
The impact of a specific warm-up on hamstring flexibility in individuals with hamstring tightness: A focus on active
1Department of Physical Therapy, College of Health and Welfare, Woosong University, Daejeon, Republic of Korea; Department of Digital Bio-Health Convergence, College of Health and Welfare, Woosong University, Daejeon, Republic of Korea.
Background:
For preventing injury in specific muscles, a targeted warm-up (WU) involving repetitive functional movements may be more effective than a general WU. However, the scientific basis for the commonly recommended six repetitions of active knee extension (AKE) to enhance hamstring flexibility is unclear.
Objective:
This study aimed to examine how the number of AKE repetitions influences hamstring flexibility, specifically by evaluating the effect of a 15-repetition WU protocol in individuals with hamstring tightness.
Methods:
Nineteen healthy young adults with significant hamstring tightness (AKE >15°) participated in the study. Hamstring flexibility was assessed using the straight leg raise (SLR) and AKE tests before (Pre-AKE or Pre-SLR) and after the WU (Post-AKE or Post-SLR). The WU consisted of 15 continuous AKE repetitions performed without rest.
Results:
A moderate correlation was observed between Pre-AKE and Pre-SLR (p = 0.024). Significant improvements in flexibility were found, with mean changes of 6.5° in Post-AKE (p = 0.001) and 6.2° in Post-SLR (p < 0.001). Flexibility gains were most notable early, leveling off after the third to fourth repetition.
Conclusion:
These findings suggest that specific WU can effectively improve flexibility of the targeted muscles, though benefits may plateau after the early repetitions. In clinical settings, to avoid under- or overestimating the intervention effects, WU should be performed in advance.
