Autonomic adaptation to repeated cold water ingestion: time-resolved HRV analysis

Heart rate variability, ECG minor changes, and HRV–ECG coupling associated with an adjunctive structured breathing–meditation protocol in combat-exposed military personnel

Introduction Combat-related stress is associated with autonomic nervous system (ANS) dysregulation—sympathetic predominance, reduced vagal tone, and decreased heart rate variability (HRV)—linked to increased cardiovascular risk. Non-pharmacological interventions targeting autonomic regulation show promise, but controll...

Aging amplifies context-dependent variability in postural long-latency reflexes without enhancing reflex selectivity

Falls are the leading cause of injury-related death in older adults, yet neural mechanisms underlying age-related balance decline remain poorly understood. Long-latency reflexes (LLRs; 50−100 ms) are particularly vulnerable to aging and represent a promising target for fall prevention. We examined whether wobble-board...

Distributed Neural Substrates for Autonomic Control During Human Thermoregulation: Brain Network Configurations of Sympathetic and Parasympathetic Innervation

Sleep-timing irregularity moderates the within-participant association between training load and next-morning heart rate variability in university sport participants: a 28-day study.

Background Heart rate variability (HRV) describes beat-to-beat variation in cardiac intervals; the root mean square of successive differences (RMSSD) is a time-domain index of short-term cardiac vagal modulation. We examined whether nightly deviation from habitual sleep midpoint moderated the association between prior-...

HRV-Based Respiratory-Rate Estimation in Older Adults: Error Modeling and Pilot Validation for Wearable Sleep Monitoring

Respiratory frequency is a critical biomarker in sleep medicine and circadian biology. We investigated whether the high-frequency (HF) component of heart-rate variability (HRV)—which reflects respiratory sinus arrhythmia (RSA)—can serve as a non-invasive proxy for breathing rate estimation from ECG or PPG. We employed...

Physiological activation regimes reveal distinct autonomic mechanisms underlying operational performance under cognitive workload and stress

Human performance in safety-critical environments depends on the interaction between mental workload, stress, autonomic regulation, and behavior. This study investigated whether associations between heart rate variability (HRV) and performance varied across physiological activation ranges and operational contexts dur...