Heart rate variability and cortisol responses to acute low-and moderate-intensity exercise in stress-related exhaustion

Published October 25, 2026. Adults with stress-related exhaustion showed different HRV recovery patterns after low- and moderate-intensity cycling than healthy controls. The study may help refine questions about exercise intensity and recovery, but it did not test HRV biofeedback or show that one exercise prescription improves symptoms.

Kling J, Ekblom Ö, Persson Asplund R, Hallman DM, Jiang Y, Blom V.
European Journal of Applied Physiology · Publication date: 2026-10-25
Added to site: 2026-10-27
DOI: 10.1007/s00421-026-06467-4

Published October 25, 2026. Added to Neurofeedback.com October 27, 2026 after being deferred one day by the prior run's five-study cap.

Modalities

Heart rate variability, Salivary cortisol

Clinical focus

Stress-related exhaustion, Exercise intensity, Recovery physiology

Population

Adults with stress-related exhaustion and age- and sex-comparable healthy controls

Sample

30 participants with stress-related exhaustion and 29 healthy controls; about 93% of each group were women

Intervention / method

Each participant completed separate 22-minute cycling sessions at 40% and 55% of estimated maximal oxygen uptake, with HRV and salivary cortisol measured before and after exercise

Comparator

Within-participant low- versus moderate-intensity exercise and between-group comparison with healthy controls

Clinician summary

Participants with stress-related exhaustion had lower RMSSD overall, especially after exercise. Within that group, moderate versus low intensity was associated with lower RMSSD and higher SD2/SD1 and LF/HF; controls showed no intensity effect. HRV during exercise did not differ between groups, and cortisol analyses suggested group differences without clear time-point effects.

How to interpret the findings

The sample was small and overwhelmingly female, limiting generalization. Workloads were based on estimated rather than directly measured maximal oxygen uptake. Physiological differences do not establish clinical benefit, and the study did not test biofeedback, longer-term training, symptoms or functional recovery. The trial was registered retrospectively, and the abstract omits detailed adverse-event and attrition information.

Equipment and disclosures

The study measured HRV and cortisol around exercise and did not test a biofeedback platform. No equipment is attributed to BrainMaster or another vendor.

Retrospectively registered as ClinicalTrials.gov NCT06429423. Crossref lists support from Stiftelsen för Kunskaps- och Kompetensutveckling. Competing-interest information was not available in the checked abstract or retained Crossref record. No correction, retraction or expression-of-concern relation appeared in the retained records; this is a bounded check. AI-assisted source review.

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