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Effect of Low Volume Sprint Interval Training on Cardiorespiratory Fitness

The Effect of Low Volume Sprint Interval Training on Cardiorespiratory Fitness--a Randomized Controlled Trial

Who can join

Ages 18 to 55 · All sexes

Inclusion Criteria:

* Healthy
* BMI \< 35 kg/m2
* younger than 56 yr old
* no joint issues

Exclusion Criteria:

* Those adults who are currently active and not weight stable
* Adults with BMI \> 35 kg/m2
* Use of medications which may alter study outcomes

About the study

Low levels of physical activity (PA) are related to poor health and greater risk of premature death in adults. Lack of time is cited as a primary barrier to partaking in PA. In the last 20 years, a lot of attention has been directed towards the efficacy of high intensity interval training (HIIT), which consists of brief, intense bursts of PA separated by recovery. One primary benefit of HIIT is a sizable increase in cardiorespiratory fitness (CRF), which enables adults to exercise better and reduce health risks due to the strong link between health status and CRF.

Completion of cardiovascular exercise is typically recommended for all adults to increase CRF, yet it takes a lot of time and may be perceived as boring. Alternatively, HIIT requires less time and tends to cause greater feelings of enjoyment in many adults. Hundreds of studies report an increase in CRF in response to HIIT in various groups of adults ranging from athletes and those with obesity, diabetes, cancer, stroke, and even spinal cord injury, which emphasizes the potency of this vigorous form of PA. Yet, many studies are weakened by a small sample size which questions the feasibility of these findings.

This randomized controlled trial will test the efficacy and feasibility of a very small amount of HIIT, referred to as reduced exertion high intensity interval training (REHIT), in inactive adults. In the proposed study, REHIT will consist of 2 days per week of 1 to two 10 - 20 second sprints on a stationary bike. The proposed sample will include 60 adults who complete 18 sessions of REHIT over a 9 week period, and their responses will be compared to a non exercising control group. During the study, changes in CRF, fuel metabolism, and psychological responses will be monitored, with the latter outcome shedding light on the overall feasibility of HIIT in inactive adults.

Overall, this novel study has profound public health applications as it will assess fitness and health related changes to a small dose of PA in the largest sample to date. If substantial changes in CRF are shown, these data have the potential to modify public health guidelines for implementing PA in inactive adults.

What is being tested

• High intensity interval training (other)

Sponsor: California State University, San Marcos · Participants: 60 · Started: Nov 5, 2025

Contact the study team

• Todd A Astorino, Ph.D · Phone: 760750-7351

Official record on ClinicalTrials.gov — NCT07328568

Locations in the U.S.

Conditions

• Health Risks of an Inactive Lifestyle
• Overweight

From ClinicalTrials.gov, data retrieved Sep 30, 2026. Each study sets its own eligibility; the study team decides who can join.