# Effect of cluster set resistance training combined with high-intensity interval training on cardiorespiratory and muscular fitness in untrained young men

PMID: 41438108
Journal: PeerJ
Published: 2025
Authors: Ma J, Ye R, Bo S, Cheng Y

## Question

Does cluster-set resistance training combined with HIIT improve cardiorespiratory and muscular fitness differently than traditional resistance training combined with HIIT in untrained young men?

## Summary

In untrained young men, 12 weeks of resistance training plus treadmill HIIT improved strength, training volume, VO2max, jumping, body fat percentage, and muscle thickness. Adding short intra-set rests during resistance training produced similar outcomes to traditional continuous sets.

## Population

- Untrained young men aged 18-28 years
- Sample size: 22
- Age: 18-28 years eligible
- Sex: Male
- Fitness level: No regular physical activity within past year; PARS-3 <=19
- Health status: Excluded exercise contraindications and recent musculoskeletal injury

## Methodology

- Randomized two-arm exercise-training study
- 12-week intervention after 1-week adaptation
- University exercise setting in Beijing, China
- Randomized and controlled study design.

## Protocol

- CSRT-HIIT.
- Modality: Resistance training plus treadmill HIIT.
- Work intervals: HIIT 1 minute.
- Recovery: HIIT 1 minute; CSRT 30 seconds intra-set after 5 reps.
- Sets or repetitions: 4 resistance exercises x 2 sets x 10 reps; 5 HIIT cycles.
- Intensity: 70% 1RM; 85-95% VO2max.
- Session duration: Resistance training plus 15-minute HIIT block after 10 minutes of resistance intervention.
- Program length: 12 weeks.
- TRT-HIIT.
- Modality: Resistance training plus treadmill HIIT.
- Work intervals: HIIT 1 minute.
- Recovery: HIIT 1 minute; 90 seconds between resistance sets.
- Sets or repetitions: 4 resistance exercises x 2 sets x 10 reps; 5 HIIT cycles.
- Intensity: 70% 1RM; 85-95% VO2max.
- Program length: 12 weeks.

## Outcomes

### Fitness
Status: improved
Both groups improved strength, training volume, VO2max, jumping, and muscle thickness.

Within-group p<0.05.

### Body fat
Status: improved
Body fat percentage decreased in both groups.

p<0.05.

### Group difference
Status: no clear change
CSRT-HIIT and TRT-HIIT did not differ significantly on the measured outcomes.

Between-group p>0.05.

## Practical Insights

- A short 5 x 1-minute treadmill HIIT block can be combined with resistance training.
- Cluster sets can make strength work feel more manageable without reducing fitness gains.

## Limitations

- Small sample
- Male-only
- No HIIT-only arm
- No long-term follow-up
- Limited adherence/safety reporting

## Safety And Adherence

- Article did not report adverse events or injuries.
- Four of 26 participants withdrew for personal reasons; these withdrawals were not attributed to adverse events.
- The study excluded recent fracture/joint injury and contraindications such as asthma, heart disease, and tumors, used a one-week adaptation phase, and supervised/monitored testing and training.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/41438108/) (pubmed)
- [DOI](https://doi.org/10.7717/peerj.20492) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12721101/) (full text)

## Agent Guidance

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