Decreasing sprint duration from 20 to 10 s during reduced-exertion high-intensity interval training (REHIT) attenuates the increase in maximal aerobic capacity but has no effect on affective and perceptual responses.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 29172029 · doi:10.1139/apnm-2017-0597
What was done
Thirty-six sedentary or recreationally active participants (17 women, age 22 ± 3 years, BMI 24.5 ± 4.6 kg·m⁻², maximal aerobic capacity 37 ± 8 mL·kg⁻¹·min⁻¹) were randomized to either a standard REHIT protocol (2 × 20-s sprints) or a shortened protocol (2 × 10-s sprints). Both groups completed 3 weekly sessions for 6 weeks. Maximal aerobic capacity was measured before and after training, and acute affective responses and perceived exertion were assessed during training.
What was found
The 20-s sprint group experienced significantly greater improvements in maximal aerobic capacity (+10%, from 2.77 ± 0.75 to 3.04 ± 0.75 L·min⁻¹) than the 10-s sprint group (+4%, from 2.58 ± 0.57 to 2.67 ± 3.04 L·min⁻¹; group × time interaction p < 0.05, d = 1.06). Across both groups, positive affect and vigour increased post-exercise, while tension, depression, and total mood disturbance decreased, and negative affect was unchanged. Affective responses and perceived exertion did not differ between the 10-s and 20-s protocols and were not altered across the training period.
Why it matters
This study defines a minimum effective sprint duration for REHIT, showing that reducing sprint duration to 10 seconds compromises cardiorespiratory fitness gains without conferring any affective or perceptual advantages.
Limits
The sample was small (n = 36) and restricted to young (mean age 22), healthy adults, limiting generalizability to older or clinical populations. The study only examined a 6-week intervention and did not assess long-term compliance or broader metabolic health endpoints.
Cited by
- supports The reduced-exertion high-intensity training (REHIT) protocol developed by researchers Metcalfe and Vollaard consists of a 10-minute total workout incorporating only one to two 10- to 20-second maximal efforts.