Abstract
The passive straight-leg-raise (PSLR) and the sit-and-reach (SR) tests have been widely
used to assess hamstring extensibility. However, it remains unclear to what extent
hamstring stiffness (a measure of material properties) contributes to PSLR and SR
test scores. Therefore, we aimed to clarify the relationship between hamstring stiffness
and PSLR and SR scores using ultrasound shear wave elastography. Ninety-eight healthy
subjects completed the study. Each subject completed PSLR testing, and classic and
modified SR testing of the right leg. Muscle shear modulus of the biceps femoris,
semitendinosus, and semimembranosus was quantified as an index of muscle stiffness.
The relationships between shear modulus of each muscle and PSLR or SR scores were
calculated using Pearson’s product-moment correlation coefficients. Shear modulus
of the semitendinosus and semimembranosus showed negative correlations with the two
PSLR and two SR scores (absolute r value≤0.484). Shear modulus of the biceps femoris
was significantly correlated with the PSLR score determined by the examiner and the
modified SR score (absolute r value≤0.308). The present findings suggest that PSLR
and SR test scores are strongly influenced by factors other than hamstring stiffness
and therefore might not accurately evaluate hamstring stiffness.
Key words
range of motion - ultrasound shear wave elastography - biceps femoris - semitendinosus
- semimembranosus
