Relation between subjective and objective scores on the active straight leg raising test.

DESIGN: Cross sectional. OBJECTIVE: To fill a gap in the validation of the active straight leg raising (ASLR) test concerning the relation between a patient's subjective score on the ASLR test and the objective measured force. SUMMARY OF BACKGROUND DATA: The ASLR test is used to classify patients presenting with pain in the low back and/or pelvic girdle. Although its reliability and validity have been demonstrated, some details are still lacking. METHODS: The ASLR test was performed by 21 parous women with various ASLR scores. Subjective weakness was scored by the patient both with and without a pelvic belt; moreover the isometric forces of leg raising were measured. RESULTS: The correlation coefficients between the subjective ASLR score and objective measured force at 0 and 20 cm elevation were -0.58 (P < 0.01) and -0.52 (P < 0.05), respectively, at the left side; and -0.45 (P < 0.05) and -0.63 (P < 0.01), respectively, at the right side. When measured with a pelvic belt the correlations were, respectively, -0.51 and -0.48 at the left side, and -0.47 and -0.50 at the right side (all P < 0.05). After applying a pelvic belt the mean subjective ASLR score decreased with 0.38 point at the left side and 0.48 point at the right side (both P < 0.05). With the belt, the measured force at 0 cm elevation increased by 11.6% (P < 0.001) at the left side and by 8.6% (P < 0.05) at the right side; at 20 cm elevation the changes in measured force were negligible. No significant correlation was found between the subjective and the objective changes elicited by the pelvic belt. CONCLUSION: The subjective scores on the ASLR test correlate well with the objective measured forces; this supports the reliability of the ASLR test. The subjective influence of a pelvic belt on the ASLR score could not be objectified.