Analysis of fluidity of movement in parkour using one inertial measurement system

Purpose: Fluidity is a multi-parametric aspect of movement; its quantification and the evaluation of its variability may guide the performance evaluation, training and rehabilitation decisions. Therefore, this study’s primary goal was to establish whether a quantitative measure of fluidity through a single wearable MIMU was accurate enough to highlight meaningful differences between advanced and novice athletes.The secondary goal was to highlight intra-individual differences of fluidity between various parts and subsequent repetitions of the same track. Methods: Seventeen parkour participants, subdivided into two groups based on their expertise, were recruited. A wearable inertial measurement unit was worn on the back of the pelvis by each participant during three sequential repetitions of a specially created parkour routine. Two fluidity parameters, namely smoothness and hesitation, were considered. Smoothness was calculated as the number of inflexions on the so-called jerk graph. Hesitation was defined as the percentage of the drop in the CoM velocity. Results: The smoothness is an encouraging parameter to quantitatively estimate the fluidity of movement in an acrobatic sport like parkour. In particular, it resulted significantly lower in advanced athletes (mean: 126.4; range: 36–192) than in beginners (mean: 179.37; range: 98–272) during the wall run’s parkour movement (Kruskal Wallis; p = 0.02). Moreover, a qualitative analysis of hesitation showed that beginner athletes tend to produce more prominent velocity drops and negative deflection than more advanced athletes. Conclusions: A MIMU-based system allows measuring fluidity and assessing its variability, providing unique data about sports performance, potentially beneficial to guide and evaluate the training and rehabilitation process.