# Effects of heat stimulation after high-intensity interval training on serum adipokines, eHSP72, and immunoglobulins in men with obesity

PMID: 41323564
Journal: Journal of exercise science and fitness
Published: 2025 Oct
Authors: Kim DH, Kim ES, Lee JS, Yoon SJ

## Question

What are the effects of heat stimulation after HIIT on adipokines, eHSP72, and immunoglobulins in men with obesity?

## Summary

In 48 men with obesity, 12 weeks of HIIT followed by heat stimulation, MICT followed by heat stimulation, or heat stimulation alone improved adipokine markers. The HIIT plus heat group and MICT plus heat group improved body weight, BMI, and body fat percentage, and HIIT plus heat showed the largest eHSP72 response.

## Population

- Adult men with obesity aged 20-40 years
- Sample size: 48
- Age: Group means approximately 25.1-28.1 years
- Sex: Male
- Fitness level: No regular exercise programs within previous 3 months
- Health status: Obesity by BMI, body fat percentage, and waist circumference; major cardiometabolic/musculoskeletal/endocrine disorders excluded

## Methodology

- Randomized three-arm controlled intervention
- 12 weeks
- Exercise and heat-stimulation research setting in Korea
- Randomized and controlled study design.

## Protocol

- HIIT plus heat stimulation.
- Modality: Cycle ergometer HIIT and hot water immersion.
- Work intervals: 4 minutes.
- Recovery: 3 minutes active recovery.
- Sets or repetitions: 4 intervals.
- Intensity: 85-95% HRmax for work bouts; 70% HRmax recovery; 40 C hot water immersion.
- Session duration: About 33 minutes exercise block plus stretching and 20 minutes heat stimulation.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.
- MICT plus heat or heat only.
- Modality: Cycle ergometer MICT plus hot water immersion; hot water immersion only.
- Work intervals: MICTHS: 40 minutes continuous cycling.
- Intensity: MICTHS cycling at 60-70% HRmax; heat stimulation 20 minutes at 40 C.
- Session duration: MICTHS 40 minutes cycling plus warm-up/stretching and 20 minutes heat stimulation; HS 20 minutes heat stimulation.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.

## Outcomes

### Body composition
Status: improved
HIITHS and MICTHS improved body weight, BMI, and body fat percentage.

### Adipokines
Status: improved
Adiponectin increased and leptin decreased in all groups.

### eHSP72
Status: improved
eHSP72 increased, with the greatest response in HIITHS.

### Immunoglobulins
Status: mixed
IgA and IgG increased; IgE decreased in HIITHS and HS.

## Practical Insights

- Post-exercise heat is a distinct intervention and should not be bundled into ordinary HIIT recommendations.
- Heat exposure after HIIT requires screening and clear dosing.

## Limitations

- No HIIT-only group
- Male-only obesity sample
- Biomarker-focused outcomes

## Safety And Adherence

- No adverse events, heat-related complications, or safety concerns were observed during the 12-week intervention.
- All 48 participants completed the protocol without missed sessions or early terminations related to heat intolerance.
- No participants reported dizziness, nausea, vomiting, excessive fatigue, headache, palpitations, chest discomfort, shortness of breath, muscle cramps, or faintness.
- Post-heat temperatures remained within normal physiological limits, and no sessions required early termination or temperature-management interventions; 20 minutes hot water immersion at 40 C was reported as well tolerated and safe in men with obesity.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/41323564/) (pubmed)
- [DOI](https://doi.org/10.1016/j.jesf.2025.11.002) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12664045/) (full text)

## Agent Guidance

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