Twelve weeks of sprint interval training increases peak cardiac output in previously untrained individuals

William Bostad; Sydney E Valentino; Devin G McCarthy; Douglas L Richards; Martin J MacInnis; Maureen J MacDonald; Martin J Gibala

doi:10.1007/s00421-021-04714-4

Twelve weeks of sprint interval training increases peak cardiac output in previously untrained individuals

Eur J Appl Physiol. 2021 Sep;121(9):2449-2458. doi: 10.1007/s00421-021-04714-4. Epub 2021 May 20.

Authors

William Bostad¹, Sydney E Valentino¹, Devin G McCarthy¹, Douglas L Richards², Martin J MacInnis³, Maureen J MacDonald¹, Martin J Gibala⁴

Affiliations

¹ Department of Kinesiology, McMaster University, Hamilton, ON, L8S 4K1, Canada.
² Department of Medicine, McMaster University, Hamilton, ON, Canada.
³ Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.
⁴ Department of Kinesiology, McMaster University, Hamilton, ON, L8S 4K1, Canada. gibalam@mcmaster.ca.

PMID: 34014402
DOI: 10.1007/s00421-021-04714-4

Abstract

Introduction: Sprint interval training (SIT), characterized by brief bouts of 'supramaximal' exercise interspersed with recovery periods, increases peak oxygen uptake ([Formula: see text]) despite a low total exercise volume. Per the Fick principle, increased [Formula: see text] is attributable to increased peak cardiac output ([Formula: see text]) and/or peak arterio-venous oxygen difference (a-vO_2diff). There are limited and equivocal data regarding the physiological basis for SIT-induced increases in [Formula: see text], with most studies lasting ≤ 6 weeks.

Purpose: To determine the effect of 12 weeks of SIT on [Formula: see text], measured using inert gas rebreathing, and the relationship between changes in [Formula: see text] and [Formula: see text].

Methods: 15 healthy untrained adults [6 males, 9 females; 21 ± 2 y (mean ± SD)] performed 28 ± 3 training sessions. Each session involved a 2-min warm-up at 50 W, 3 × 20-s 'all-out' cycling bouts (581 ± 221 W) interspersed with 2-min of recovery, and a 3-min cool-down at 50 W.

Results: Measurements performed before and after training showed that 12 weeks of SIT increased [Formula: see text] (17.0 ± 3.7 vs 18.1 ± 4.6 L/min, p = 0.01, partial η² = 0.28) and [Formula: see text] (2.63 ± 0.78 vs 3.18 ± 1.1 L/min, p < 0.01, partial η² = 0.58). The changes in these two variables were correlated (r² = 0.46, p < 0.01). Calculated peak a-vO_2diff also increased after training (154 ± 22 vs 174 ± 23 ml O₂/L; p < 0.01) and was correlated with the change in [Formula: see text] (r² = 0.33, p = 0.03). Exploratory analyses revealed an interaction (p < 0.01) such that [Formula: see text] increased in male (+ 10%, p < 0.01) but not female participants (+ 0.6%, p = 0.96), suggesting potential sex-specific differences.

Conclusion: Twelve weeks of SIT increased [Formula: see text] by 6% in previously untrained participants and the change was correlated with the larger 21% increase in [Formula: see text].

Keywords: Central adaptations; Exercise; Inert gas rebreathing; Peak oxygen uptake; Peripheral adaptations.

MeSH terms

Adaptation, Physiological / physiology
Bicycling*
Cardiac Output / physiology*
Female
High-Intensity Interval Training*
Humans
Male
Muscle, Skeletal / physiology
Young Adult