A multi-joint lower-limb tracking-trajectory test for the assessment of motor coordination

This study aimed to determine whether a lower-limb trajectory-tracking task performed on a leg press machine, that is commonly adopted in both rehabilitation and resistance training settings, could yield reliable assessment of motor coordination in able-bodied individuals. Twenty-two female subjects allocated to two experimental groups were tested and retested after 48-72 h. Group A was fully familiarized with the experimental procedures before each test while group B received only verbal instructions. The unilateral coordination test consisted of target tracking during a simulated half squat including eccentric and concentric actions. In both groups, tracking error showed significant test-retest reliability with ICC values of 0.77-0.80 (p < 0.05). Significant group (A < B) and time (day 2 < day 1) main effects were found for tracking error, while there was no significant influence of action mode and dominance. Tracking error significantly decreased in the group A (∼15%) but not in the group B on retest. Action mode (eccentric versus concentric), side dominance and familiarization on day 1 had no effect on tracking error. However, movement control significantly improved at day 2, thus confirming the occurrence of short-term motor learning and the sensitivity of the present trajectory-tracking test. For the first time, a simple test for the assessment of motor coordination during multi-joint closed-kinetic chain action of lower limb muscles has been proposed. Its uniqueness is represented by the specificity for rehabilitation and resistance training settings. Further studies with larger sample groups (e.g., male subjects and patients) and including neurophysiological measurements are needed.