# A 12-Week Pilot Study Comparing High-Intensity Interval Training and Peripheral Heart Action Training on ISAK-Based Anthropometric Outcomes and Perceived Psychophysical Well-Being in Young Adults

PMID: 41893593
Journal: Sports
Published: 2026-03-04
Authors: Domenico FD, Ceruso R, Raiola G, Aliberti S, Esposito G

## Question

How do 12 weeks of HIIT and PHA training differ in ISAK anthropometric outcomes and perceived psychophysical well-being in moderately active young adults?

## Summary

This small non-randomized pilot study compared 12 weeks of supervised HIIT with peripheral heart action circuit training in 24 moderately active adults. Both groups improved several anthropometric indicators over time, while HIIT showed larger reductions in selected skinfolds and higher perceived performance improvement, and PHA showed larger increases in arm circumferences and mesomorphy. Because allocation was non-randomized, there was no inactive control group, and adherence was not systematically quantified, findings are exploratory.

## Population

- Twenty-four adults recruited from a personal training studio; HIIT n=12 and PHA n=12.
- Sample size: 24
- Age: Overall 30.9 +/- 3.5 years; HIIT 30.42 +/- 3.37; PHA 31.42 +/- 3.65
- Sex: 12 males and 12 females overall; HIIT 5M/7F, PHA 7M/5F
- Fitness level: Moderately active; regular physical activity for at least 12 months
- Health status: Adults without medical conditions limiting exercise; baseline BMI 24.5 +/- 3.3 kg/m2

## Methodology

- Non-randomized longitudinal pilot trial with repeated measures
- 12 weeks
- Supervised real-world personal training studio in Salerno, Italy
- Controlled study design.

## Protocol

- Functional circuit HIIT.
- Modality: Mixed functional circuit.
- Work intervals: 30 sec per exercise.
- Recovery: 30 sec passive recovery; 1 min between rounds.
- Sets or repetitions: Six exercises, four rounds.
- Intensity: 80-95% HRmax.
- Session duration: About 45-50 min including 10-min warm-up, 24-min circuit, and 10-min cool-down.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.
- Progression: Uniform protocol across participants; substitutions limited to functionally equivalent movements.
- Peripheral heart action training.
- Modality: Circuit alternating upper- and lower-body exercises.
- Work intervals: 40 sec per exercise.
- Recovery: 20 sec rest; 1 min between rounds.
- Sets or repetitions: Six exercises, four rounds.
- Intensity: 70-80% HRmax.
- Session duration: Approximately 50-60 min.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.
- Progression: Uniform protocol across participants; one exercise substitution reported in PHA.

## Outcomes

### Anthropometric/body composition indicators
Status: improved
Both groups improved several anthropometric indicators over time, including reductions in BMI, waist/hip circumference, skinfolds, and endomorphy.

LMM time effects for body mass, BMI, sum of skinfolds, waist circumference, hip circumference, endomorphy, and mesomorphy were significant; p values ranged from <0.05 to <0.001

### Protocol-specific adaptation patterns
Status: mixed
HIIT favored reductions in selected skinfolds; PHA favored arm circumference and mesomorphy increases. Overall superiority was not established.

Significant Time x Group interactions for body mass p<0.001, BMI p<0.01, sum of skinfolds p<0.01, waist circumference p<0.05, and endomorphy p<0.05

### Psychophysical well-being
Status: mixed
Psychological and physical/functional well-being did not differ between groups, but HIIT reported higher perceived performance improvement.

Performance improvement: HIIT 4.63 +/- 0.43 vs PHA 3.04 +/- 0.54, p<0.001; psychological p=0.225; physical/functional p=0.415

## Practical Insights

- A supervised HR-monitored HIIT circuit is feasible in a personal training studio, but this study did not quantify attendance or compliance rates.
- Claims about body composition effects should remain exploratory without randomization or a non-exercise control group.
- The HIIT protocol requires multiple pieces of equipment and is not directly app-only translatable.

## Limitations

- Small pilot sample.
- Non-randomized allocation by schedule and previous training routine.
- No non-exercise control group.
- Psychophysical questionnaire was non-validated and administered only after the intervention.
- No objective performance or VO2max outcome.
- No sex-stratified inferential analysis.
- Attendance and lifestyle compliance were not systematically quantified.

## Safety And Adherence

- No formal adverse event counts were reported. Exercise substitutions were required in 3 participants because of orthopedic or technical limitations.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/41893593/) (pubmed)
- [DOI](https://doi.org/10.3390/sports14030102) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13030102/) (full text)

## Agent Guidance

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