Cardiac autonomic function during submaximal treadmill exercise in adults with Down syndrome

Area of Science:

• Cardiology
• Exercise Physiology
• Neuroscience

Background:

• Cardiac autonomic function is crucial for adapting to physical demands.
• Down syndrome (DS) is associated with various health complications, including potential cardiovascular differences.
• Understanding autonomic responses during exercise in DS is vital for health management.

Purpose of the Study:

• To compare cardiac autonomic function between adults with Down syndrome (DS) and nondisabled individuals during submaximal dynamic exercise.
• To investigate heart rate variability (HRV) and heart rate (HR) responses during rest, exercise, and recovery.

Main Methods:

• 13 adults with DS and 12 controls underwent maximal and submaximal treadmill tests.
• Metabolic and HR measurements were collected.
• Spectral analysis of HRV was performed at rest, during submaximal exercise, and during recovery.

Main Results:

• Participants with DS exhibited a lower chronotropic response to exercise compared to controls.
• Despite similar peak HR utilization (~60%), individuals with DS showed a higher LF/HF ratio and LF power during exercise, indicating heightened sympathetic modulation.
• No significant differences in HF power or autonomic function were observed at rest or during recovery.

Conclusions:

• Adults with DS demonstrate appropriate vagal withdrawal but increased sympathetic modulation of HRV during submaximal exercise.
• The absolute HR change from rest to exercise was attenuated in adults with DS, suggesting poorer cardiac responsiveness.
• Down syndrome may be linked to diminished cardiac adaptability to autonomic changes during exercise below the ventilatory threshold.