Does Biological Sex Influence the Cardiac Output Response to Sprint Interval Exercise Training in Humans?

The primary purpose of this study is to determine whether biological sex influences the peak cardiac output response to 12 weeks of sprint interval exercise training. Peak cardiac output will be determined non-invasively using an inert gas rebreathing technique. Each session of sprint interval exercise training will involve a 10-minute period of cycling on a stationary ergometer. The protocol will consist of a two-minute warm-up; three, 20-second 'all out' efforts that are separated by two minutes of recovery; and a three-minute cool down. Three sessions of training will be performed each week for a total of 12 weeks. Groups of male and female participants will be recruited and tested using best practice guidelines for sex-based comparisons of exercise responses. The study will advance knowledge regarding the potential for biological sex to influence the cardiovascular response to brief vigorous cycle exercise training.

Inclusion criteria

• Being untrained based on a self-report of engaging in < 1 h of weekly moderate to vigorous physical activity based on the Canadian Society for Exercise Physiology Get Active Questionnaire.
• Having an estimated cardiorespiratory fitness in the lower 50% of adults in the specified age range based on the online fitness calculator available at: www.worldfitnesslevel.org.
• Females who are naturally cycling (i.e., not using any form of hormonal contraceptive) or are using a 2nd generation oral contraceptive.

Exclusion criteria

• Experiencing a condition that might preclude safe participation in physical activity and exercise, as determined by answering "Yes" to any question on Page 1 of the Canadian Society for Exercise Physiology Get Active Questionnaire.
• Females with a positive pregnancy test.