Cardiorespiratory Coordination During Exercise in Adults With Down Syndrome

Area of Science:

• Cardiorespiratory Physiology
• Exercise Science
• Genetics and Human Health

Background:

• Down syndrome (DS) is a genetic disorder impacting cardiovascular and respiratory systems.
• Cardiorespiratory coordination (CRC) quantifies cardiorespiratory system coupling during exercise.
• No prior research has investigated CRC in adults with DS during exercise testing.

Purpose of the Study:

• To compare cardiorespiratory coordination (CRC) between adults with and without Down syndrome (DS) during maximal cardiorespiratory exercise testing.
• To evaluate differences in cardiorespiratory system covariation during exercise in individuals with and without DS.

Main Methods:

• Maximal cardiorespiratory exercise testing was performed on 15 adults with DS and 15 controls.
• Time series data from six cardiorespiratory variables (ventilation, expired O2/CO2 fractions, heart rate, SBP, DBP) were analyzed.
• Principal component analysis (PCA) was used to compute CRC metrics: number of principal components (PCs), PC1 eigenvalues, and information entropy.

Main Results:

• The DS group required three PCs to explain cardiorespiratory variable variance, versus two PCs in the non-DS group.
• Systolic and diastolic blood pressure shifted to a separate PC in the DS group.
• PC1 eigenvalues were lower (p=0.02), and information entropy was higher (p=0.008) in the DS group, indicating reduced coordination efficiency.

Conclusions:

• Adults with Down syndrome demonstrate higher cardiorespiratory coordination dimensionality and entropy during maximal exercise.
• These findings suggest a less efficient cardiorespiratory system in adults with DS during exertion.
• CRC offers a novel approach to assess cardiorespiratory function and exercise response in the DS population.