Modifications to the net knee moments lead to the greatest improvements in accelerative sprinting performance: a predictive simulation study

Abstract

The current body of sprinting biomechanics literature together with the front-side mechanics coaching framework provide various technique recommendations for improving performance. However, few studies have attempted to systematically explore technique modifications from a performance enhancement perspective. The aims of this investigation were therefore to explore how hypothetical technique modifications affect accelerative sprinting performance and assess whether the hypothetical modifications support the front-side mechanics coaching framework. A three-dimensional musculoskeletal model scaled to an international male sprinter was used in combination with direct collocation optimal control to perform (data-tracking and predictive) simulations of the preliminary steps of accelerative sprinting. The predictive simulations differed in the net joint moments that were left ‘free’ to change. It was found that the ‘knee-free’ and ‘knee-hip-free’ simulations resulted in the greatest performance improvements (13.8% and 21.9%, respectively), due to a greater knee flexor moment around touchdown (e.g., 141.2 vs. 70.5 Nm) and a delayed and greater knee extensor moment during stance (e.g., 188.5 vs. 137.5 Nm). Lastly, the predictive simulations which led to the greatest improvements were also found to not exhibit clear and noticeable front-side mechanics technique, thus the underpinning principles of the coaching framework may not be the only key aspect governing accelerative sprinting.

Lower-limb coordination changes following a six-week training intervention that elicited enhancements to maximum velocity sprint performance

“…For thigh-shank coordination, the INT group reduced clockwise and increased anti-clockwise thigh rotation during ipsilateral early swing, reflecting reduced backside mechanics, which has recently been shown via predictive simulations to be associated with improved sprint acceleration performance (Haralabidis et al, 2022). During contralateral early swing (lead thigh retraction after maximum thigh separation) an earlier onset of clockwise thigh rotation was observed for the INT group (Figure 2).…”

“…For example, Clark et al (2020) demonstrated a strong positive linear relationship between average thigh angular velocity across the entire stride cycle and ground reaction force production during subsequent stance, indicating the importance of thigh angular velocity for achieving increased maximal velocity. Additionally, the 'front-side' mechanics framework proposed by Mann and Murphy (2015) suggests that swing phase thigh rotations are crucial to maximal sprint velocity, with recent predictive simulations supporting the importance of reducing thigh extension in early swing (Haralabidis et al, 2022). However, an evaluation of how functionally linked system components move relative to each other (i.e.…”