Effects of Heat Therapy on Exercise Tolerance in a Rat Model of Heart Failure with Preserved Ejection Fraction

Michael D Belbis ^1,2, Bohyun Ro ¹, Luke E Schepers ³

⁰Department of Health and Kinesiology, Purdue University, West Lafayette, IN.

Journal of Applied Physiology (Bethesda, Md. : 1985) +

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June 14, 2025

View abstract on PubMed

Summary

Chronic whole-body heat therapy (HT) improved exercise tolerance and cardiac function in a heart failure with preserved ejection fraction (HFpEF) rat model. Heat therapy enhanced body composition and muscle oxygenation, offering a potential new treatment for HFpEF patients.

Area Of Science

Cardiovascular Physiology
Metabolic Disease Research
Therapeutic Modalities

Background

Heart failure with preserved ejection fraction (HFpEF) is characterized by impaired cardiac and skeletal muscle function, leading to reduced exercise capacity.
Current therapeutic options for improving physical function in HFpEF are limited.
Whole-body heat therapy (HT) has emerged as a potential intervention for various cardiovascular conditions.

Purpose Of The Study

To investigate the effects of chronic whole-body heat therapy (HT) on exercise tolerance and physiological adaptations in a pre-clinical model of HFpEF.
To test the hypothesis that HT induces central and peripheral adaptations that enhance exercise capacity in HFpEF.

Main Methods

Male obese ZSF1 rats were subjected to 8 weeks of daily whole-body heat therapy (HT) at 39°C or control (CON) conditions at room temperature (~22°C).
Comprehensive assessments included exercise tolerance tests, body composition analysis, echocardiography, and skeletal muscle interstitial oxygenation (PO2) measurements.
Nitric oxide synthase inhibition (L-NAME) was used to evaluate the role of nitric oxide bioavailability.

Main Results

Heat therapy (HT) prevented the decline in exercise tolerance observed in the control (CON) group, maintaining performance post-intervention.
HT preserved left ventricular ejection fraction, whereas the CON group showed a significant decline.
HT improved body composition by reducing fat mass and increasing lean mass, and enhanced skeletal muscle oxygenation (PO2), partly through increased nitric oxide bioavailability.

Conclusions

Chronic whole-body heat therapy demonstrates significant benefits in improving exercise tolerance and cardiac function in a pre-clinical model of HFpEF.
HT promotes beneficial central and peripheral adaptations, including improved body composition and enhanced muscle oxygenation.
These findings suggest that heat therapy is a promising non-pharmacological intervention for managing HFpEF and improving physical capacity.

Keywords:

HFpEF body composition nitric oxide obese ZSF1 skeletal muscle

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