How do movement patterns in weightlifting (clean) change when using lighter or heavier barbell loads? – a comparison of two principal component analysis-based approaches to studying technique

This
study compared whole-body kinematics of the clean movement when lifting three
different loads, using two data analysis approaches based on PCA.

Nine
weightlifters were equipped with 39 markers and their motion captured with 8
Vicon cameras at 100 Hz. Lifts of 60%, 85% and 95% of the one repetition
maximum were analysed. The first PCA (PCA_trial) analysed variance among
time-normed waveforms compiled from subjects and trials; the second PCA
(PCA_posture) analysed postural positions compiled over time, subjects and
trials.

PCA_trial
scores differed in the first and fifth principal component, suggesting that
increased barbell load produced higher initial elevation, lower squat position,
wider feet position after squatting, and less inclined arms.

PCA_posture revealed significant timing
differences in all components.