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Comparative Study
, 15, 223

Lower Hamstring Extensibility in Men Compared to Women Is Explained by Differences in Stretch Tolerance

Comparative Study

Lower Hamstring Extensibility in Men Compared to Women Is Explained by Differences in Stretch Tolerance

Paul W M Marshall et al. BMC Musculoskelet Disord.


Background: This study examined whether passive hamstring tissue stiffness and/or stretch tolerance explain the relationship between sex and hamstring extensibility.

Methods: Ninety healthy participants, 45 men and 45 women (mean ± SD; age 24.6 ± 5.9 years, height 1.72 ± 0.09 m, weight 74.6 ± 14.1 kg) volunteered for this study. The instrumented straight leg raise was used to determine hamstring extensibility and allow measurement of stiffness and stretch tolerance (visual analog pain score, VAS).

Results: Hamstring extensibility was 9.9° greater in women compared to men (p = 0.003). VAS scores were 16 mm lower in women (p = 0.001). Maximal stiffness (maximal applied torque) was not different between men and women (p = 0.42). Passive stiffness (slope from 20-50° hip flexion) was 0.09 Nm.°(-1) lower in women (p = 0.025). For women, linear and stepwise regression showed that no predictor variables were associated with hamstring extensibility (adjusted r(2) = -0.03, p = 0.61). For men, 44% of the variance in hamstring extensibility was explained by VAS and maximal applied torque (adjusted r(2) = 0.44, p < 0.001), with 41% of the model accounted for by the relationship between higher VAS scores and lower extensibility (standardized β coefficient = -0.64, p < 0.001).

Conclusions: The results of this study suggest that stretch tolerance and not passive stiffness explains hamstring extensibility, but this relationship is only manifest in men.


Figure 1
Figure 1
Representative results from a man and woman tested in this study for the torque measured during the instrumented straight leg raise test (iSLR). Passive tissue stiffness was measured as the slope (∆y/∆x) through the common range of motion (Megrad, 20-50°), and peak torque applied during the iSLR (Memax). Maximum leg excursion angle (leg°max) was used to represent hamstring extensibility in this study (male, 67°; female, 87°). Observe the lower Megrad, and greater leg°max for the female participant, but similar Memax. Note that VAS pain scores were 66 and 4 mm respectively for the male and female participant results presented here.
Figure 2
Figure 2
Relationship between hamstring extensibility (degrees; °) and visual analog pain scores (VAS; mm) for men (n = 45) and women (45) in this study. Trend lines are displayed for men and women, with a significant association between VAS and hamstring extensibility for men only (adjusted r2 = 0.41, standardized β coefficient = -0.64, p < 0.001).

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