Standardizing Fatigue in Resisted-Sprint Training: The Role of a Time-Based Training Approach

Studies comparing acute responses after resisted-sprint training (RST) have traditionally used running distances for prescribing volume. The aim of this study was to compare the acute responses to heavy and light sled RST loads where volume was matched by sprint time instead of distance.

Twenty-one physically active men completed 2 experimental sessions, each consisting of eight 5-second bouts of sled RST with 2 minutes of rest between bouts. The RST loads were set to reduce unresisted 20-m sprinting speed by 10% (light load; VL10) and 50% (heavy load; VL50). Blood lactate concentration, countermovement jump (CMJ) height, and 10- and 20-m sprint times (T10 and T20) were assessed before and after each protocol. Performance variables were also measured at 24 hours postexercise.

No significant differences between loads were observed in CMJ height and sprint times. Lactate significantly increased (ηp2=.86; P < .001; VL10: 7.0 [3.2]; VL50: 8.7 [4.3]) for both groups. VL10 and VL50 significantly impaired their CMJ height after training (ηp2=.43; P < .001; VL10: -5.6% [6.2%]; VL50: -8.4% [6.9%]) but not T10 and T20. At 24 hours, CMJ height was restored while sprint performance significantly decreased (ηp2=.31 and .29 for T10 and T20, respectively; P < .001).

Coaches and practitioners can prescribe RST volume based on sprint time to ensure a consistent training stimulus regardless of the load used. By standardizing sprint duration rather than distance, athletes can experience similar mechanical and physiological responses across different resistance levels, which minimizes confounding variables.