Active hip and spine ROM differs when comparing unconstrained motion with voluntary segmental constraint

Active range of motion trials are frequently used as a baseline for normalizing other data. However, previous research has not focused on methods utilized to achieve maximum active range of motion.

Twenty-seven males (age 20-38 years) participated in this study. Active hip extension in upright standing was compared to active lumbar extension with regards to degrees of total hip and spine extension obtained. Similarly, active spine rotation whereby participants attempted to constrain associated pelvis and hip rotation was compared to rotation trials in which the pelvis and hips were free to rotate concurrently. An infra-red motion capture system and associated software were used to capture movement and determine joint angles.

Results indicate that average degrees of hip extension did not differ between the two methods (p = 0.138), nor did either method result more frequently in the highest measurement. Spine extension values were significantly greater in the active spine extension manoeuvre compared to the associated back extension that occurred when participants were asked to actively extend their hip (p < 0.001). Average degrees of spine rotation were greater in the unconstrained trials: when concurrent hip and pelvis rotation were allowed to take place (p < 0.001). Of the 27 participants, 23 obtained maximum rotation during the unconstrained trials.

To obtain maximum active hip joint extension, both hip and back extension trials should be collected. Maximum spine rotation is more likely to occur when the pelvis and hips are unconstrained.