Reliability of the Active Knee Extension Test and the Straight Leg Raise Test in Subjects With Flexibility Deficits.

The objective of this study was to determine the AKE and the SLR intrarater (test-retest) reliability, in subjects with flexibility deficits, as well as the correlation between the two tests. One hundred and two volunteers (48 males, 54 females) participated in this study. They were all recreationally active, injury free to the lower limbs, and had flexibility deficits in the hamstrings muscle group. All participants performed, in each lower limb, two trials with both the AKE and the SLR. The ICC values found for AKE and SLR tests were, respectively, 0.87 – 0.94 and 0.93 – 0.97. The values for SEM were low for both tests (2.6° – 2.9° for AKE; 2.2° – 2.6° for SLR), as well as the calculated MDD (7° – 8° for AKE; 6° – 7° for SLR). A moderate to strong, and significant, correlation between AKE and SLR was determined either for the dominant limb (r = 0.71) or the non-dominant limb (r = 0.67).

These findings indicate that both AKE and SLR have an excellent intrarater reliability. The SEM and MDD values recorded are also very encouraging for the use of these tests in patients with flexibility deficits.