Optimizing phase variability threshold for automated synchrogram analysis of cardiorespiratory interactions in...

Area of Science:

• Cardiovascular Physiology
• Computational Biology
• Respiratory Medicine

Background:

• Cardiorespiratory interactions are crucial for physiological regulation.
• Assessing phase synchronization requires robust analytical methods.
• Inspiratory muscle training (IMT) may influence cardiorespiratory coupling.

Purpose of the Study:

• To introduce a novel, automated procedure for analyzing synchrograms to detect phase synchronization.
• To evaluate the impact of IMT on cardiorespiratory phase synchronization in amateur cyclists.
• To compare the proposed method with traditional thresholding approaches.

Main Methods:

• Developed a likelihood-maximization procedure using surrogate data to test for phase synchronization.
• Applied the method to analyze cardiorespiratory phase interactions (heartbeat and inspiratory onset).
• Compared results before and after an 11-week IMT program at varying intensities.

Main Results:

• The new procedure successfully identified decreased cardiorespiratory phase locking during postural changes (supine to standing) associated with vagal withdrawal.
• IMT demonstrated minimal effects on cardiorespiratory phase synchronization strength, irrespective of training intensity.
• The observed decrease in phase synchronization in the upright position was not significantly altered by IMT.

Conclusions:

• The proposed automated synchrogram analysis is effective for detecting phase synchronization epochs.
• IMT in amateur athletes has a limited impact on cardiorespiratory phase synchronization, suggesting inspiratory muscles are not a limiting factor in this context.
• The findings highlight the modest influence of IMT intensity on cardiac vagal control and subsequent cardiorespiratory coupling.