Metabolic flexibility and resting autonomic function in active menopausal women

Area of Science:

• Cardiovascular Physiology
• Metabolic Health
• Aging Research

Background:

• Heart Rate Variability (HRV) reflects cardiac autonomic control.
• Metabolic flexibility is crucial for energy utilization and health.
• Aging impacts both autonomic function and metabolism.

Purpose of the Study:

• To investigate the relationship between resting HRV and metabolic flexibility in active postmenopausal women.
• To assess fat oxidation (FATox) and carbohydrate oxidation (CHOox) rates at maximum intensities (MFO and MCO).

Main Methods:

• HRV was measured in 24 active women (aged ~67 years) using 10-min resting recordings.
• An incremental cycling test determined maximal fat and carbohydrate oxidation rates.
• Nonlinear HRV analysis (SampEn, DFAα1) and traditional HRV metrics were employed.

Main Results:

• Resting nonlinear HRV measures (SampEn, DFAα1) correlated with FATox and CHOox at FATmax intensity.
• No association between HRV and oxidation rates was found at MCO intensity.
• DFAα1, LF/HF ratio, and SD1/SD2 ratio correlated with blood lactate concentration at MCO intensity.

Conclusions:

• Enhanced resting autonomic function, indicated by HRV, is associated with better metabolic flexibility in postmenopausal women.
• Nonlinear HRV analysis (DFAα1, SampEn) is suitable for assessing autonomic-cardiovascular health in aging.
• Findings support the autonomic resources hypothesis and highlight HRV's role in metabolic health with aging.