Assessing High-Intensity Acceleration Efforts Using Local Positioning System—Introducing the Concept of the Relative Acceleration Threshold to Ice Hockey

Current methods for assessing acceleration efforts (acc_efforts) in ice hockey do not account for the influence of initial skating speed on maximal voluntary acceleration capacity, which may lead to a biased evaluation of acc_effort intensity. In this study, we introduce the conceptual approach of the relative acceleration threshold (rel_threshold) to ice hockey and outline its potential benefits for the assessment of acc_efforts. Locomotion data derived from observations of 17 players across 10 official games were used to model the initial-skating-speed-dependent maximal voluntary acceleration capacity (a_max-v_{init capacity}), from which a team-specific rel_threshold was determined (rel_{threshold_75%} = 3.23 - 0.365v_init), and, subsequently, applied to assess acc_efforts alongside a fix threshold set at 2 m·s^-2 (fix_{threshold_2}). Differences in acc_efforts depended on the method used (rel_{threshold_75%} vs. fix_{threshold_2}) as well as the playing position when using the rel_{threshold_75%}. The fix_{threshold_2} reported 89.1 ± 35.8% more acc_efforts than the rel_{threshold_75%}. However, only one-third of these acc_efforts exceeded rel_{threshold_75%}, which is considered indicative of neuromuscularly intense acc_efforts according to the modeled a_max-v_{init capacity}. Moreover, at skating speeds above 4 m·s^-1, the fix_{threshold_2} only assessed a negligible number of acc_efforts, whereas the rel_{threshold_75%} assessed 27.2 ± 9.3% of all its acc_efforts. In line with established theoretical rationales, the observational findings of this study suggest that an acceleration threshold adapted to the initial skating speed offers a conceptually more valid approach to assessing acc_efforts in ice hockey.