The active knee extension test and slump test in subjects with perceived hamstring tightness

Background. Reduced hamstring extensibility is commonly assumed to be due to stiffness or decreased length of the hamstring muscle group. The first aim of this study was to collect data on the results of the active knee extension test in subjects with perceived reduction in hamstring extensibility. The second aim was to establish the prevalence and location of symptoms induced by the Slump test in those subjects with perceived hamstring tightness. Methods. Forty-two asymptomatic subjects (M = 21, F = 21, mean age 23.6, range 18–35) with perceived right hamstring tightness performed the active knee extension test followed by the Slump test. A goniometer and digital photography were used to measure the knee flexion angle of the active knee extension test. A body chart was used to record the location of pain or discomfort produced or relieved during the active performance of the Slump test. Results. Subjects had an average knee flexion angle of 35.2° (SD 14.2; range 15.6–70°). During the Slump test 66.7% (n = 28) of the subjects reported symptoms in the posterior knee, 35.7% (n = 15) reported symptoms in the posterior thigh and 33.3% (n = 13) reported symptoms in the posterior leg. Combined prevalence of cervical and thoracic symptoms was 14.2%, with only 7.1% experiencing symptoms in the thoracic region. At the last stage of the Slump test 12.0% (n = 5) of subjects had no change in symptoms, whilst 83.3% (n = 35) of subjects had either partial relief (n = 19) or complete relief (n = 16) of symptoms. Discussion and conclusion. Subjects with perceived hamstring tightness did not appear to have reduced hamstring extensibility when compared to the available normative data. Only 7.1% of subjects reported thoracic symptoms during the Slump test, compared to other reports of thoracic symptoms in approximately 50% of asymptomatic subjects. The high prevalence of posterior lower extremity symptoms induced by the Slump test amongst asymptomatic subjects, which are relieved by cervical extension, suggests that neural structures may contribute to perceived hamstring tightness and the sensation of discomfort produced during hamstring stretches.