# Real-world efficacy of equipment-free reduced-exertion high-intensity interval training in improving physical and mental health in inactive males: A randomized controlled trial

PMID: 40689309
Journal: Journal of Exercise Science and Fitness
Published: 2025-06-25
Authors: Hu M, Chen X, Nie J, Shi Q, Kong Z

## Question

Can equipment-free reduced-exertion HIIT, delivered either supervised or in a real-world self-managed format, improve physical and mental health in inactive men compared with cycling SIT and no exercise?

## Summary

In inactive young men, a 12-week program of very brief burpee-style intervals improved body mass, VO2max, blood pressure, and several mental-health questionnaire measures compared with no exercise. A real-world unsupervised version produced smaller VO2max gains than supervised burpees but better affect/enjoyment and no reported adverse events. The evidence is highly relevant to equipment-free HIIT, but only in young men and with short-term follow-up.

## Population

- Inactive healthy young men.
- Sample size: 319
- Age: Mean 20.5 +/- 1.1 years.
- Sex: Male.
- Fitness level: Inactive.
- Health status: Healthy; BMI >30 and chronic disease excluded.

## Methodology

- Four-arm randomized controlled trial.
- 12 weeks.
- University setting in Tianjin, China; supervised office sessions and participant-chosen real-world settings.
- Randomized and controlled study design.

## Protocol

- BIT / BIT-RW.
- Modality: Equipment-free burpee-jump intervals.
- Work intervals: 20 s all-out.
- Recovery: 10 s passive recovery.
- Sets or repetitions: 2 bouts.
- Intensity: All-out; >85% HRmax and RPE >8 thresholds for real-world sessions.
- Session duration: About 2 min including 1-min warm-up.
- Frequency: 3-5 sessions/week.
- Program length: 12 weeks.
- Progression: Maximize completed burpees/jumps; no formal interval progression.
- SIT and control.
- Modality: Cycle ergometer SIT or no exercise.
- Work intervals: 20 s cycling sprint.
- Recovery: 10 s passive recovery.
- Sets or repetitions: 2 bouts.
- Intensity: All-out cycling sprint.
- Session duration: About 2 min including warm-up.
- Frequency: 5 sessions/week for SIT; none for control.
- Program length: 12 weeks.
- Progression: Cycling resistance progressed from 1 kg toward 5% body mass.

## Outcomes

### VO2max
Status: improved
All exercise groups improved VO2max; supervised BIT matched SIT and BIT-RW improved less but still improved versus control.

Exercise groups +8-13%; supervised BIT and SIT +5.0 +/- 0.6 mL/kg/min; BIT-RW +3.0 +/- 0.6 mL/kg/min.

### Body mass and blood pressure
Status: improved
Exercise groups reduced body mass/BMI and blood pressure compared with control.

Body mass reductions about 6-8%, p < .001.

### Mental health and affect
Status: improved
Stress, anxiety, depression, resilience, and quality of life improved; BIT-RW had the most favorable affect/enjoyment.

Reported stress -49-61%, anxiety -37-86%, depression -14-48%, resilience +22-27%, QoL +14-27%.

### Sleep
Status: no clear change
Sleep did not improve significantly by group.

Sleep group effect p = .380; change group effect p = .537.

## Practical Insights

- A 2-min bodyweight HIIT format is highly app-translatable.
- Real-world delivery may improve enjoyment while slightly reducing fitness gains.
- Burpee protocols need lower-impact options and soreness expectations.

## Limitations

- Inactive young male sample only.
- No long-term follow-up.
- No detailed body composition imaging or strength outcomes.
- Healthy baseline mental health limits mental-health generalization.
- No direct energy expenditure, appetite, or hormone data.

## Safety And Adherence

- BIT-RW had no adverse events.
- Supervised BIT caused upper-body and thigh soreness, especially in the first 2 weeks.
- SIT caused four nausea/vomiting events immediately after sessions in weeks 1-4.
- All events were mild-moderate, transient, and resolved without medical intervention.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/40689309/) (pubmed)
- [DOI](https://doi.org/10.1016/j.jesf.2025.06.006) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12273568/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.