Comparison of active, manual, and instrumental straight leg raise in measuring hamstring extensibility

The active manual straight leg raise (ASLR) and passive manual straight leg raise (MSLR) tests are commonly used in clinical settings to assess hamstring tightness. However, to our knowledge, the validity and sensitivity of these tests have not been compared with the instrumental straight leg raise (ISLR). The aim of the present study was to assess the intrarater reproducibility of the ISLR and compare the sensitivity of the ASLR, MSLR, and ISLR to change. Twelve men with hamstring tightness underwent the ASLR, MSLR, and ISLR tests at baseline and after a 4-week home-based right leg stretching program with the left leg serving as a control. The ISLR measurements were repeated consecutively at baseline to assess reproducibility. The intraclass correlation coefficient for the ISLR was 0.94, and the coefficient of reproducibility was 6. Significant differences in the range of motion emerged between all testing methods (p < 0.05). In the stretched legs, the mean +/- SD increases were 17 +/- 5 degrees for ISLR, 10 +/- 8 degrees for ASLR, and 6 +/- 5 degrees for MSLR, whereas the control legs showed a significant mean change only for ASLR (5 +/- 4 degrees ). The mean standard response with the ASLR and MSLR tests did not differentiate between the treated and control legs, but it was almost 10-fold higher in the treated leg than the control leg for the ISLR, clearly differentiating between them. The ISLR had good reproducibility and sensitivity to changes, whereas ASLR and MSLR showed a poor ability to detect changes. Thus, the ISLR test is recommended for use in research evaluating the effectiveness of stretching.