Cross-Correlation of Lower Limb Joint Angular Kinematic Signal for Coordination Assessment During Impulse Phase on Standard Maximum Vertical Jump

This study presents and applies cross-correlation analysis of lower limb joint angular kinematic signal for coordination assessment during impulse phase of standard Maximum Vertical Jump (MVJ). Standard MVJ has been applied for noninvasive subject specific analysis at Counter Movement Jump (CMJ) and Drop Jump (DJ) with long and short Counter Movement (CM) for comparison with Squat Jump (SJ) and no CM. Long and short CM are intrinsically related to the underlying mechanisms of muscle Stretch–Shortening Cycle (SSC) with the integration of muscular action and synergistic joint coordination an open issue on the contribution for the task to perform. Lower limb joint coordination has thus received increasing research interest as an external observed result of the neuromuscular control mechanisms and the hypotheses of training and repetition contribution for stereotyped coordination with the need of objective tools considering entire time series while avoiding subjective point selection for coordination assessment. The results of maximum cross-correlation (CCr max) and corresponding time delay (τ) from entire time series of the Hip (H), the Knee (K) and the Ankle (A) joints angular displacement (θ), angular velocities (ω) and angular accelerations (α) during a fifty-four trial sample with long, short and no CM performed by a group of healthy untrained subjects conduced to detection of maximum synchrony with null τ of the lower limb θ at different conditions, whereas ω and α CCr led to detection of different time delay for CCr max with dominant negative τ values corresponding to a proximal–distal coordination sequence at H–K-A. These results point thus for the need to consider entire time series of joint ω and α in addition to joint θ to detect different joint coordination and avoid subjective point selection for coordination assessment.