# Influence of upper-body high-intensity intermittent training on energy metabolism and maximal oxygen uptake in elite swimmers

PMID: 41030318
Journal: Frontiers in Physiology
Published: 2025
Authors: Zhang L, Li H, Wang T, Chen C

## Question

Does 4 weeks of upper-body high-intensity intermittent training improve energy metabolism and maximal oxygen uptake more than moderate-intensity continuous upper-body training in elite swimmers?

## Summary

In elite swimmers, 4 weeks of supervised upper-body Tabata-style resistance-band HIIT improved VO2max and several energy-system measures more than a matched moderate-intensity circuit. The protocol was short and sport-specific, and the evidence is most relevant to trained athletes rather than general fitness users.

## Population

- Elite freestyle, backstroke, and butterfly swimmers from a local sports faculty.
- Sample size: 24
- Age: 20.71 +/- 1.38 years
- Sex: 16 male and 8 female
- Fitness level: Elite swimmers with about 10.6 years of training history
- Health status: Free from chronic pain and cardiovascular disease; met national first-class athlete standard

## Methodology

- Randomized controlled longitudinal training study
- 4 weeks
- Supervised dry-land training and laboratory testing at a sports faculty
- Randomized and controlled study design.

## Protocol

- Upper-body HIIT.
- Modality: Resistance-band upper-body circuit.
- Work intervals: 20 seconds.
- Recovery: 10 seconds between exercises; 3 minutes between sets.
- Sets or repetitions: Eight upper-body exercises per circuit, repeated for 3 sets.
- Intensity: Maximum effort with target at or above 85% HRmax.
- Session duration: 60 minutes total including 20 minute warm-up, 30 minute main training, and 10 minute cooldown/stretching.
- Frequency: 3 sessions per week.
- Program length: 4 weeks; 12 sessions.
- Progression: No major dose progression reported; intensity maintained by HR and RPE monitoring.
- Upper-body MICT.
- Modality: Resistance-band upper-body circuit using the same exercise menu.
- Work intervals: 60 seconds per exercise.
- Recovery: 20 seconds between exercises.
- Sets or repetitions: Eight exercises repeated for 3 sets.
- Intensity: 60-69% HRmax.
- Session duration: 60 minutes total including the same warm-up and cooldown structure.
- Frequency: 3 sessions per week.
- Program length: 4 weeks; 12 sessions.
- Progression: No major dose progression reported.

## Outcomes

### Glycolysis
Status: improved
HIIT increased glycolytic contribution while MICT did not.

Group x time F(1,22)=87.882, p<0.001, eta2=0.800; HIIT 39.12 +/- 8.69 to 52.42 +/- 8.47, p<0.001; MICT 35.51 +/- 9.19 to 34.66 +/- 8.96, p>0.05.

### Aerobic oxidation
Status: improved
HIIT improved aerobic oxidation more than MICT.

Group x time F(1,22)=63.809, p<0.001; HIIT 104.94 +/- 30.83 to 148.17 +/- 30.73, p<0.001; post-test HIIT greater than MICT, p<0.001.

### Phosphagen
Status: improved
HIIT produced a significant phosphagen-system improvement.

Group effect F=6.376, p<0.05; time effect F=25.342, p<0.001; group x time F=29.338, p<0.001.

### VO2max
Status: improved
VO2max improved after HIIT and was superior to MICT after training.

The article reports significant time and interaction effects for VO2max favoring HIIT, p<0.05.

## Practical Insights

- A dry-land upper-body Tabata circuit can improve sport-relevant aerobic and anaerobic measures in already trained swimmers.
- The intervention used simple resistance-band movements but required close supervision, HR tracking, and athlete-level effort.
- This study should not be used as direct evidence for untrained adults or lower-body/bodyweight HIIT.

## Limitations

- Small sample of elite swimmers.
- Short 4-week intervention.
- No direct swimming race-performance or stroke-kinematic outcomes.
- Upper-body dry-land protocol limits generalization to whole-body HIIT.
- Athlete-only sample limits applicability to general users.

## Safety And Adherence

- All participants completed the training and testing.
- Testing deviations were corrected promptly to reduce injury risk.
- No adverse events were reported in the full text.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/41030318/) (pubmed)
- [DOI](https://doi.org/10.3389/fphys.2025.1636405) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12477251/) (full text)

## Agent Guidance

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