Interlimb asymmetry thresholds that negatively affect change of direction performance in collegiate American football players

Abstract

Purpose: Investigations into the effects of interlimb asymmetries on different aspects of sport performance have been of increased interest to researchers and strength and conditioning practitioners over the past couple of years. Interlimb asymmetries have been found to negatively impact performance in key performance indicators (KPI) such as jumping, sprinting, and changing directions, within various sports populations. However, there is no consensus with regard to a meaningful threshold at which asymmetries start to negatively impact KPIs or performance. The aim of this study was to investigate a potentially meaningful threshold for three asymmetry metrics (mean peak velocity (mPV), mean peak power (mPP), mean average power (mAP)) that were extracted from the Bulgarian split squat and found to be significantly related to change of direction performance (via L-drill test) within a sample of collegiate American football players. Methods: We used receiver operating characteristic (ROC) curves to identify asymmetry thresholds for all metrics that discriminate between faster and slower performers in the L-drill. Results: Asymmetry thresholds of greater than 10.65% (mAP), 14.59% (MPP), and 14.96% (mPV) were the thresholds identified by ROC curves as approximately 15% for both metrics, whereby players with asymmetries over this threshold were more likely to be classified as low performers. Conclusion: These findings may be helpful for practitioners interested in screening athletes for interlimb asymmetries that may negatively impact their change of direction performance.

Reducing Limb Asymmetry in Females Collegiate Basketball: A Randomized Trial

“…This raises questions about the specificity and transference of asymmetry effects across different performance indicators. Philipp et al (2020) extended this discourse, emphasizing that interlimb asymmetry could indeed have a deleterious impact on an athlete's ability to perform key tasks such as jumping and sprinting. However, the study was inconclusive regarding the "critical threshold" at which asymmetry impacts performance , a lacuna echoed by Dos'Santos (2020).…”

“…Basketball as a sport places unique demands on lower extremity capabilities, thereby necessitating a deeper understanding of how limb strength asymmetry could affect performance and injury susceptibility in female collegiate athletes. Previous research has underscored the negative consequences of interlimb strength asymmetry on key performance metrics such as jumping and sprinting (Philipp et al, 2020;Boccia et al, 2018). However, these studies often produce inconsistent results, and the field lacks a universally accepted threshold to determine what level of asymmetry is "problematic" (Dos'Santos, 2020; Bettariga et al, 2022).…”