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Supramaximal Intensity Hypoxic Exercise and Vascular Function Assessment in Mice
Published on: March 15, 2019
Caffeine stimulates ventilation in athletes with exercise-induced hypoxemia
Robert F Chapman1, Joel M Stager
1Human Performance Laboratory, Department of Kinesiology, Indiana University, Bloomington, IN 47405, USA. rfchapma@indiana.edu
Medicine and Science in Sports and Exercise
|May 8, 2008
Summary
Caffeine supplementation improved exercise ventilation and oxygen saturation in athletes with exercise-induced hypoxemia. However, it did not alter maximal oxygen uptake or resting ventilatory responses.
Area of Science:
- Exercise Physiology
- Sports Science
- Respiratory Physiology
Background:
- Athletes with exercise-induced hypoxemia (EIH) often exhibit inadequate ventilatory responses during exercise.
- Low resting ventilatory responsiveness is also common in athletes with EIH.
Purpose of the Study:
- To investigate if caffeine, a known ventilatory stimulant, can enhance resting ventilatory responsiveness, exercise ventilation (VE), end-tidal O2 partial pressure (PetO2), and arterial oxyhemoglobin saturation (HbSaO2) in athletes with EIH.
Main Methods:
- Eight highly trained male athletes with EIH participated in a randomized, placebo-controlled study.
- Caffeine (8 mg/kg) or placebo was ingested 1 hour before progressive treadmill exercise to exhaustion.
- Resting ventilatory responsiveness was assessed using hypoxic and hyperoxic hypercapnic ventilatory responses (HVR and HCVR).
Main Results:
- Caffeine increased exercise ventilation (VE) at 75%, 80%, and 100% of VO2max.
- VE/VO2, PetO2, and HbSaO2 were elevated at submaximal exercise intensities (75-90% VO2max) with caffeine.
- No significant changes in VO2max or resting HVR/HCVR were observed. Increased VE appeared to stem from central stimulation.
Conclusions:
- Caffeine augments submaximal exercise ventilation and oxygenation in athletes with EIH.
- The lack of HbSaO2 improvement at maximal exercise suggests other factors influence oxygen saturation beyond hyperventilation.
- Individual variability in mechanisms affecting HbSaO2 may exist as maximal exercise intensity is approached.
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