NCT07328568

Effect of Low Volume Sprint Interval Training on Cardiorespiratory Fitness

Active, enrolled NA Last updated 9 January 2026

What this trial tests

NA trial testing High intensity interval training in Inactivity, Physical in 60 participants. Participants enrolled and being followed up; not accepting new ones.

Timeline

1 September 2025

Primary endpoint
30 August 2028

30 August 2028

Quick facts

Lead sponsor	California State University, San Marcos
Phase	NA
Status	Active, enrolled
Study type	INTERVENTIONAL
Allocation	randomized
Design	parallel
Masking	none
Primary purpose	prevention
Enrollment	60
Start date	1 September 2025
Primary completion	30 August 2028
Estimated completion	30 August 2028
Sites	1 location across United States

Drugs / interventions tested

• High intensity interval training

Conditions studied

• Inactivity, Physical — all drugs for Inactivity, Physical →
• Overweight (BMI > 25) — all drugs for Overweight (BMI > 25) →
• Healthy Participants — all drugs for Healthy Participants →

Sponsor

California State University, San Marcos

Who can join

Adults 18 to 64, any sex, with Inactivity, Physical or Overweight (BMI > 25). Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

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.

Publications & conference data

1 peer-reviewed publication reference this trial (live from Europe PMC):

1. The effect of low volume sprint interval training on cardiorespiratory fitness: study protocol for a definitive randomized controlled trial.
   Astorino TA, Metcalfe RS, Vollaard NBJ. · · 2026 · PMID 41872855 · DOI 10.1186/s13063-026-09647-x