A novel approach to improve hamstring flexibility: A single-blinded randomised clinical trial.

Background: The hamstrings play a major role in body posture. Shortening or tightness of the hamstrings affects postural alignment and results in possible musculoskeletal pain.

Objectives: The aim of this study was to develop a novel approach to improve hamstring flexibility in young adults.

Method: A single-blinded randomised clinical trial included 60 participants aged 18-24 with shortened hamstrings recruited from the Hashemite University, Zarqa, Jordan. The range of motion of knee extension was measured with the hip at 90° flexion using a simple goniometer to detect the level of hamstring flexibility. Participants received either a passive hamstring stretch (PS), followed by two sets of 10 tibial nerve neurodynamic technique (ND), or PS followed by three sets of 10 repetitions of active knee extension-quadriceps activation (QA), or PS only.

Results: There was a significant improvement of hamstring flexibility in the QA group compared to the PS group (13.4 ± 12.1° vs. 6.2 ± 6.4°, = 0.05). There was a significant improvement in hamstring flexibility post-intervention compared to pre-intervention in the PS group by 6.2 ± 6.4 (30.5 ± 10.8° vs. 36.6 ± 9.5°, = 0.001), ND group by 9.3 ± 6.2 (26.7 ± 10.9° vs. 36.0 ± 9.5°, = 0.001) and QA group by 13.4 ± 12.1 (20.3 ± 9.0° vs. 33.4 ± 8.9°, = 0.001).

Conclusion: Quadriceps muscle activation following passive stretching of the hamstrings appears to be superior to the PS and ND techniques in improving hamstring muscle flexibility.

Clinical Implications: Quadriceps activation following passive hamstring stretching can be used in physiotherapy settings to improve hamstring muscle flexibility.