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Exercise performance following a carbohydrate load in chronic airflow obstruction.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|April 1, 1985
Summary
High carbohydrate intake significantly reduces exercise capacity in patients with chronic airflow obstruction by limiting ventilation, despite increased glucose levels. Normal individuals showed no such effect, highlighting a specific impact on this patient group.
Area of Science:
- Cardiopulmonary Exercise Physiology
- Respiratory Medicine
- Sports Nutrition
Background:
- Chronic airflow obstruction (CAO) impairs exercise capacity.
- The metabolic effects of carbohydrate loading on exercise performance in CAO are not well understood.
Purpose of the Study:
- To investigate the impact of a large liquid carbohydrate (CHO) load on maximal exercise capacity in patients with CAO.
- To assess the physiological responses to CHO loading during incremental exercise in this population.
Main Methods:
- 18 patients with CAO underwent duplicate incremental cycle ergometer tests to maximal exertion.
- Tests were performed after consuming a high-carbohydrate (920 kcal) liquid or a placebo in a single-blind manner.
- Expired gas analysis, arterial blood gases, and blood chemistry were measured.
Main Results:
- Carbohydrate loading significantly decreased maximum power output (86 to 76 W) in CAO patients.
- Ventilation at exhaustion remained similar, but arterial CO2 decreased and arterial O2 increased with CHO.
- CHO increased serum glucose and led to a lower limiting ventilation level at reduced power outputs in CAO patients.
- Normal subjects did not experience a significant reduction in maximum power output with CHO.
Conclusions:
- High carbohydrate intake impairs exercise capacity in patients with chronic airflow obstruction.
- This impairment appears related to reaching a ventilatory limitation at lower exercise intensities.
- The effect is specific to patients with CAO, as normal individuals were not similarly affected.