# Interaction between respiration and central motor control in autonomic cardiac regulation

## TL;DR

This study shows that voluntary movement has a stronger influence on heart regulation than breathing, and exhaling during recovery helps maintain heart health.

## Contribution

The study reveals that motor command dominates over respiration in autonomic cardiac regulation and identifies the role of expiration timing in preserving parasympathetic activity.

## Key findings

- Voluntary motor control strongly influences cardiac autonomic regulation regardless of breathing rate.
- Slow-paced breathing enhances parasympathetic activity but is disrupted by active movement.
- Expiration during the recovery phase of movement preserves parasympathetic regulation.

## Abstract

Adaptations in cardiac autonomic regulation induced by physical training are central to the health benefits of exercise. We investigated the interaction between central motor command, breathing rate, and expiration timing during an isolated joint movement. Fifteen volunteers (30.9 ± 7.2 years; 8 women) performed twelve 3-min leg extension tasks in a seated position under three randomized conditions: movement type (active vs. passive), breathing pattern (spontaneous, 12 or 6 cycles/min), and expiration timing (during extension vs. return). RR intervals and their variability were analyzed. Voluntary motor control reduced indices of autonomic and parasympathetic regulation (p < 0.05), whereas slow-paced breathing enhanced them. However, motor control exerted a dominant influence over cardiac autonomic regulation (p < 0.001), regardless of breathing rate. Expiration during the return phase was associated with greater parasympathetic activity (p < 0.05). These results highlight the central role of motor command in autonomic modulation and suggest that emphasizing expiration during recovery may help preserve parasympathetic regulation.

•Voluntary motor command exerts a stronger effect on cardiac autonomic control than respiration.•Slow-paced breathing enhances parasympathetic activity, but is disrupted by active movement.•Expiration during the recovery phase of movement preserves parasympathetic regulation.

Voluntary motor command exerts a stronger effect on cardiac autonomic control than respiration.

Slow-paced breathing enhances parasympathetic activity, but is disrupted by active movement.

Expiration during the recovery phase of movement preserves parasympathetic regulation.