Effect of Acute Heart Rate Variability Biofeedback on H-reflex Modulation: A Pilot Study

Area of Science:

• Neuroscience
• Physiology
• Biofeedback

Background:

• Heart rate variability biofeedback (HRV BFB) is a breathing technique that promotes cardiovascular resonance.
• The H-reflex is a measure of spinal cord excitability, reflecting the activity of motor neurons and sensory afferents.

Purpose of the Study:

• To investigate the acute effects of a single HRV BFB session on the H-reflex of the soleus muscle in healthy males.
• To determine if HRV BFB influences 1a afferent activation and motor neuron excitability.

Main Methods:

• A randomized crossover design was used with 12 healthy males.
• Participants underwent a 10-minute HRV BFB session and a normal breathing control (CON) session, separated by 48 hours.
• The H-reflex of the soleus muscle was measured under resting conditions.

Main Results:

• HRV BFB significantly reduced 1a afferent activation compared to the control condition.
• A lower proportion of activated motor neurons from 1a afferents was observed following HRV BFB.
• These findings indicate a reduction in motoneuron excitability after acute HRV BFB.

Conclusions:

• A single session of HRV BFB can acutely decrease motoneuron excitability at rest.
• HRV BFB may modulate spinal reflex pathways, potentially impacting motor control and excitability.
• Further research is warranted to explore the long-term effects and clinical applications of HRV BFB on neuromuscular function.