Effects of ankle dorsiflexion on active and passive unilateral straight leg raising.

The purpose of this study was to analyze the straight-leg-raising (SLR) maneuver while the ankle was fixed in dorsiflexion or relaxed in plantar flexion. Twenty-two healthy subjects underwent active and passive SLR with the ankle in each position. We used cinematography to document movement of the right lower limb and pelvis and electromyography to document hamstring muscle activity. Analyses of variance of the angles of maximum SLR and change in the pelvic position showed a significant F ratio (p = .01) among the active and passive trials. Post hoc analyses demonstrated significant differences (p = .01) between SLR with dorsiflexion and SLR with plantar flexion. The EMG activity among trials was not significantly different. The possible causes of the effects of dorsiflexion on SLR are discussed. We encourage clinicians to document and compare SLR with dorsiflexion and SLR with plantar flexion, and we recommend additional research to examine the relative influence of tissue structures on SLR.