# Exercise Load Variation at Different Subjective Intensities of High-Intensity Interval Training Using Body Weight

PMID: 40062161
Journal: Cureus
Published: 2025 Feb
Authors: Egoshi S, Kandori T, Ueno M, Shinya M, Wakiji A, Ito R

## Question

Can bodyweight HIIT exercises performed at subjective intensity levels reach a high-intensity oxygen uptake load?

## Summary

In healthy young men, bodyweight squats, front lunges, and side lunges reached more than 60% of peak VO2 when participants performed them at a subjective intensity of 'somewhat hard' or 'hard'. Fast walking reached only about 60% peak VO2 at 'hard'.

## Population

- Twenty-eight healthy male university students.
- Sample size: 28
- Age: 21.1 +/- 0.6 years
- Sex: Male
- Fitness level: Young healthy students; baseline peak VO2 2389.9 +/- 611.4 mL/min
- Health status: Healthy; no respiratory, cardiac, or lower-limb orthopedic disease

## Methodology

- Acute within-participant laboratory comparison of subjective intensity conditions
- Single testing sequence after a separate peak VO2 test
- University laboratory

## Protocol

- Bodyweight subjective-intensity HIIT.
- Modality: Squat, front lunge, side lunge, fast walking, and low-intensity foot stomping.
- Work intervals: 1 min per bodyweight exercise.
- Recovery: 1 min 30 s low-intensity foot stomping.
- Sets or repetitions: Four 1-min higher-intensity exercises alternated with four 1.5-min low-intensity bouts.
- Intensity: Subjective intensity: fairly light, somewhat hard, or hard.
- Session duration: 10 min per subjective intensity condition.
- Frequency: Acute testing.
- Program length: Acute testing.
- Progression: Conditions performed in randomized order with rest until fatigue disappeared.
- Lower subjective intensity conditions.
- Modality: Same bodyweight exercises.
- Work intervals: 1 min per exercise.
- Recovery: 1 min 30 s low-intensity foot stomping.
- Sets or repetitions: Same exercise sequence.
- Intensity: Fairly light or somewhat hard compared with hard.
- Session duration: 10 min per condition.
- Frequency: Acute testing.
- Program length: Acute testing.
- Progression: No training progression.

## Outcomes

### Squat VO2
Status: improved
Squats exceeded 60% peak VO2 at somewhat hard and hard intensities.

53.1 +/- 17.4%, 65.3 +/- 18.0%, and 76.6 +/- 25.3% peak VO2 for fairly light, somewhat hard, and hard

### Lunge VO2
Status: improved
Side and front lunges exceeded 60% peak VO2 at somewhat hard and hard intensities.

Side lunge 56.1%, 70.5%, 81.8%; front lunge 55.5%, 70.5%, 80.9% peak VO2 across the three intensity levels

### Fast walking VO2
Status: mixed
Fast walking produced lower oxygen uptake than the lunge and squat exercises and reached about 60% peak VO2 only at hard intensity.

42.3 +/- 15.8%, 52.2 +/- 16.4%, and 59.1 +/- 14.5% peak VO2

### Subjective intensity
Status: improved
VO2 and heart rate generally rose as subjective intensity increased.

VO2 increased with subjective intensity for squat, side lunge, front lunge, and fast walking (p<0.01), with some nonsignificant differences between somewhat hard and hard for squat and fast walking

## Practical Insights

- Subjective intensity can be a practical cue for bodyweight HIIT when external load is unavailable.
- Squats and lunges are more likely than fast walking to reach high-intensity oxygen uptake in young healthy men.
- Lower-limb joint load should be considered when prescribing repeated squat and lunge intervals.

## Limitations

- Acute oxygen uptake study; no longitudinal training outcomes.
- Only young healthy male university students were studied.
- Exercise depth, tempo, and movement quality were self-adjusted rather than standardized.
- Nutrition, arteriovenous oxygen difference, and muscle activity were not controlled or measured.

## Safety And Adherence

- Adverse events were not reported.
- Authors cautioned that squat and lunge exercises may impose high lower-limb joint loads and joint-pain risk.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/40062161/) (pubmed)
- [DOI](https://doi.org/10.7759/cureus.78595) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11889363/) (full text)

## Agent Guidance

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