# Effects of cycling high-intensity interval training on body composition and cardiorespiratory fitness in adults: a systematic review and meta-analysis

PMID: 41580784
Journal: BMC Sports Science, Medicine and Rehabilitation
Published: 2026-01-24
Authors: Cheng H, Song S, Shu H, Li H, Tao M, Liu B

## Question

How does cycling HIIT compare with moderate-intensity continuous training for body composition and cardiorespiratory fitness in adults?

## Summary

This meta-analysis of adult randomized trials found that cycling HIIT produced small average improvements in BMI and VO2peak compared with moderate-intensity continuous training, but did not significantly change body fat, fat mass, or lean mass overall. Effects varied strongly by population and protocol.

## Population

- Adults aged 18-60 across cycling HIIT randomized trials, including obese, sedentary, and clinical populations
- Sample size: 527
- Age: 18-60 years by inclusion criteria
- Sex: Mixed; sex-stratified analysis not available
- Fitness level: Varied: obese, sedentary, and disease groups
- Health status: Included healthy sedentary/obese adults and adults with conditions such as PCOS, diabetes, and fibromyalgia

## Methodology

- Systematic review and meta-analysis of randomized controlled trials
- Included interventions ranged from 2 to 24 weeks
- Adult cycling HIIT trials from database search
- Controlled study design.

## Protocol

- Cycling HIIT across included RCTs.
- Modality: Cycling.
- Work intervals: Varied by study, including 10-second sprints, 30-second intervals, and 4-minute intervals.
- Recovery: Varied by study.
- Sets or repetitions: Varied by study.
- Intensity: HIIT defined as 80-100% VO2peak or maximum heart rate.
- Session duration: Varied; examples ranged roughly 20-60 minutes.
- Frequency: 3-5 sessions per week.
- Program length: 2-24 weeks.
- Progression: Varied by trial.
- Moderate-intensity continuous training.
- Modality: Cycling.
- Work intervals: Continuous exercise.
- Intensity: Generally 50-75% HRmax, HR reserve, or VO2peak depending on study.
- Session duration: At least 20 minutes; commonly 20-60 minutes.
- Frequency: Varied by study.
- Program length: 2-24 weeks.
- Progression: Varied by study.

## Outcomes

### BMI
Status: improved
Cycling HIIT slightly reduced BMI compared with MICT overall, with stronger benefit in obese subgroup and opposite direction in disease subgroup.

Overall SMD about -0.24 to -0.25, 95% CI about -0.45 to -0.05, P about 0.012-0.014; high heterogeneity I2 about 78-80%

### Body fat
Status: no clear change
No significant overall body-fat effect.

SMD about -0.16 to -0.17, P = 0.160

### Fat mass
Status: no clear change
No significant overall fat-mass effect.

SMD about -0.18 to -0.19, P = 0.134

### Lean mass
Status: no clear change
No significant overall lean-mass effect.

SMD about -0.10 to -0.11, P = 0.461

### VO2peak
Status: improved
Cycling HIIT modestly improved VO2peak compared with MICT overall.

SMD about 0.25 to 0.26, 95% CI about 0.07 to 0.44, P = 0.007; I2 about 82-83%

## Practical Insights

- Cycling HIIT evidence supports small average VO2peak benefits over MICT, but protocols are heterogeneous.
- Body composition effects are not uniformly superior to MICT and may depend on obesity status and diet.
- The review's clinical suggestions emphasize screening and modified progression in comorbid populations.

## Limitations

- High protocol and population heterogeneity.
- Sex-stratified analyses were not possible.
- Dietary confounding across included trials.
- Allocation concealment and blinding were limited in many trials.
- Subgroup findings may be driven by few studies.

## Safety And Adherence

- The meta-analysis did not summarize adverse events, injuries, adherence, or tolerability from included trials as safety outcomes. It did report 527 completers across included RCTs and recommended pre-exercise risk screening, lower-intensity progression, close monitoring, and caution to avoid exercise-related adverse events in people with obesity plus comorbidities such as diabetes or fibromyalgia.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/41580784/) (pubmed)
- [DOI](https://doi.org/10.1186/s13102-025-01519-2) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12911145/) (full text)

## Agent Guidance

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