Are Running, Speed Change and Kicking Actions During Football Training Associated with Reductions in Hip Adductor Strength?

Abstract

This exploratory cross-sectional study quantified the associations between running, speed change, and kicking actions on acute hip adductor strength from football training. Twelve trained youth football players (34 observations) wore footmounted inertial measurement units during training to track football actions. Maximal isometric hip adductor squeeze strength was performed pre- and post-training to quantify change. Linear mixed models revealed moderate to large associations for all running and speed change actions (accelerations, decelerations) (r = 0.48 to –0.69, p ≤ 0.004) while associations were small and not statistically significant for the kicking metrics: ball releases, release index, and high speed releases (r = –0.24, –0.24 ,0.16, respectively, p > 0.05). The largest strength reductions were predicted by distances of high intensity accelerations (B = –0.31% per meter, 95% CI = –0.47%;0.15%), high intensity decelerations (B = –0.30% per meter, 95% CI = 0.50%;–0.12%), and counts of high intensity speed changes (B = 0.40% per count, 95% CI = –0.57%;–0.23%). On a per meter basis, high intensity accelerations and decelerations predicted a more than seven-times greater reduction in strength than sprint meters, while low intensity accelerations and decelerations predicted similar effect magnitudes when compared to high-speed running. In conclusion, running speed and speed change metrics (accelerations, decelerations) as opposed to kicking actions displayed significant associations with acute hip adductor strength reductions. As high intensity speed-change metrics predicted the largest effects in reducing hip adductor strength, practitioners may monitor and manipulate the programming of these actions within training to manage groin loading and fatigue.