Endurance training attenuates the increase in peripheral chemoreflex sensitivity with intermittent hypoxia

Area of Science:

• Cardiovascular Physiology
• Exercise Science
• Respiratory Physiology

Background:

• Patients with heart failure and sleep apnea exhibit increased chemoreflex sensitivity, linked to intermittent hypoxia (IH) and mortality.
• Peripheral chemoreflex sensitivity plays a role in cardiovascular regulation and is implicated in disease states.

Purpose of the Study:

• To investigate whether endurance training can attenuate the effect of IH on peripheral chemoreflex sensitivity in healthy humans.
• To explore the impact of endurance training on cardiovascular and autonomic responses to IH.

Main Methods:

• Fifteen healthy subjects participated; 11 underwent 8 weeks of endurance training, while 4 served as controls.
• Chemoreflex sensitivity, blood pressure, heart rate, and muscle sympathetic nerve activity (MSNA) were measured before and after 30 minutes of IH exposure.
• Training involved running and interval training; control subjects maintained their usual activity levels.

Main Results:

• Endurance training decreased resting systolic blood pressure and heart rate but did not affect resting respiratory parameters.
• Training attenuated the IH-induced increase in chemoreflex sensitivity.
• IH increased blood pressure and MSNA before training but not after training; control subjects showed no significant changes.

Conclusions:

• Endurance training effectively attenuates chemoreflex sensitization to intermittent hypoxia in healthy individuals.
• These findings suggest that exercise training may partially explain the benefits observed in patients with cardiovascular diseases.
• Attenuating chemoreflex sensitivity to IH through exercise could be a therapeutic target for managing cardiovascular conditions.