Understanding how to precisely program resisted sprinting to enhance sprint phase-based adaptations is an important yet underexplored topic. This pilot study examined the impact of high-load sled-resisted sprint training when varying distance and repetitions for the same overall volume on acceleration capabilities and performance. Twenty under-19 national-level rugby players were divided into 2 groups, performing sprint sets of short or long distances over an 8-week intervention. Resistance (~50% individual maximal velocity decrement, through load-velocity profiling) and overall volume (distance × repetitions) were equated across groups. Preintervention and postintervention testing included 10, 20, and 30 m split times, and acceleration-speed profiles to characterize maximal acceleration and speed capacities. The main effects of group, time, and their interaction were assessed using linear mixed-effects models, with the athletes as random effects, and subsequent analyses of variance. Statistically significant large mean effects were observed across for 10 m split times, maximal theoretical acceleration, and the slope of the acceleration-speed profile (omega-squared = 0.19-0.34, p < 0.044). No significant group or interaction effects were observed for any variables (p > 0.05). The findings align with existing research suggesting that high-load resisted sprinting specifically enhances acceleration capabilities. The absence of clear differences in training outcomes between the groups may be attributed to the similarity of stimuli, indicating a need for greater variation in volume distribution (e.g., increased distances per repetition) to discern effects. However, our results imply that acceleration performance improvements might be less sensitive to volume distribution variations than expected, allowing practitioners flexibility in their programming within this study's parameters.
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