Impact of Different Sprint Pedal Resistances Within Heat-Based Sprint Interval Training on Repeated Sprint Ability, Time Trial Exercise, and Recovery

Abstract McGregor, C, Marley, A, and Babraj, J. Impact of different sprint pedal resistances within heat-based sprint interval training on repeated sprint ability, time trial exercise, and recovery. J Strength Cond Res XX(X): 000–000, 2026—Sprint interval training (SIT) in temperate and hot conditions induces timely adaptations but SIT pedal resistance research is lacking. This study examined 2 sprint pedal resistances in 14 active adults assigned to a training group (TG): 0.075 kg·kg −1 (7.5 TG; 6 men, 1 female) or 0.085 kg·kg −1 (8.5 TG; 5 men, 2 women). A 15-minute time trial (TT) was completed followed by a 3-week control period and a postcontrol TT. Subjects then undertook a 3-week intervention (3 sessions/week), comprising 6 × 15-second sprints with 30 seconds recovery followed by 30 minutes of low-moderate cycling. One week later, postintervention TT began. Testing/training was performed at 38° C and 30% relative humidity. Significance was set at p ≤ 0.05. There was no change in TT distance covered during the 15-minute TT after training. Both groups improved repeated sprint ability from first to last session during sprint 1 (s1) and sprint 6 (s6) by increasing power produced during the fast desaturation (FD) phase (8.5 TG: s1: 0.0 ± 0.6 W·kg −1 , s6: 0.8 ± 0.8 W·kg −1 vs. 7.5 TG: s1: 0.1 ± 0.5 W·kg −1 , s6: 0.2 ± 0.7 W·kg −1 ). Both groups from first to last session during s1 and s6 increased FD rate (8.5 TG: s1: −2.8 ± 4.2%/s, s6: −1.8 ± 3.1%/s vs. 7.5 TG: s1: −0.4 ± 2.4%/s, s6: −1.3 ± 1.3%/s) while reducing the duration (8.5 TG: s1: −2 ± 2 seconds, s6: −2 ± 3 seconds vs. 7.5 TG: s1: −1 ± 3 seconds, s6: 0 ± 2 seconds). The 7.5 TG increased the skeletal muscle oxygen saturation recovery limit (s1: 9.0 ± 13.7%, s6: 19.3 ± 17.3%), while the 8.5 TG saw no change (s1: −9.9 ± 20.3%, s6: −10.3 ± 10.3%). Although 15-minute TT performance remained unchanged, both groups improved sprint power while the 7.5 TG favored recovery adaptations. These mechanistic findings suggest pedal resistance should align with training goals but warrant cautious interpretation.