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Resting heart rate variability and exercise capacity in Type 1 diabetes
Luke C Wilson1,2, Karen C Peebles3,4,5, Neil A Hoye6
1Department of Medicine, University of Otago, Dunedin, New Zealand Luke.wilson@otago.ac.nz.
Physiological Reports
|April 20, 2017
Summary
People with type 1 diabetes have reduced exercise capacity linked to cardiac autonomic dysfunction. Heart Rate Variability, specifically Total Power, strongly correlates with exercise capacity, outperforming traditional measures in both diabetic and non-diabetic individuals.
Area of Science:
- Cardiovascular Physiology
- Endocrinology
- Sports Medicine
Background:
- Type 1 diabetes (T1D) is associated with diminished exercise capacity (V̇O2max) compared to non-diabetic individuals (CON).
- Cardiac autonomic dysfunction may contribute to reduced exercise capacity in T1D.
- Heart Rate Variability (HRV) serves as a key indicator of cardiac autonomic modulation.
Purpose of the Study:
- To investigate the association between HRV and exercise capacity in individuals with and without T1D.
- To determine if HRV alterations are detectable in uncomplicated T1D and relate to exercise performance.
Main Methods:
- Recruited 23 participants with T1D and 17 matched CON.
- Measured heart rate (ECG), blood pressure, and respiratory rate during baseline, paced-breathing, and clinical autonomic reflex tests (CARTs).
- Analyzed HRV using frequency-domain methods from ECG.
- Assessed exercise capacity via incremental cycle ergometry, measuring V̇O2, ECG, and BP.
Main Results:
- Individuals with T1D exhibited elevated resting heart rate and reduced resting HRV metrics, suggesting altered cardiac parasympathetic modulation, often missed by CARTs.
- No significant differences in blood pressure or plasma catecholamines were observed between groups.
- V̇O2max tended to be lower in T1D (P=0.07), with significantly lower heart rate reserve (P < 0.01).
- Resting Total Power (TP) demonstrated stronger positive associations with V̇O2max (R² ≥ 0.3) than traditional indicators (age, resting HR, self-reported exercise) in both T1D and CON groups.
Conclusions:
- Cardiac autonomic modulation alterations are an early finding in uncomplicated T1D.
- Resting Total Power is significantly associated with exercise capacity, irrespective of diabetes status.
- HRV, particularly Total Power, may serve as a more robust indicator of exercise capacity than traditional metrics.