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Expiratory flow limitation confounds ventilatory response during exercise in athletes
P A Derchak1, J M Stager, D A Tanner
1Department of Kinesiology, Indiana University, Bloomington 47405, USA. pderchak@indiana.edu
Medicine and Science in Sports and Exercise
|November 18, 2000
Summary
Elite runners may have inadequate hyperventilatory responses due to expiratory flow limitation. This study found that when flow limitation is accounted for, hypoxic ventilatory responsiveness (HVR) significantly impacts oxygen saturation in highly trained athletes.
Area of Science:
- Exercise Physiology
- Respiratory Physiology
Background:
- Highly trained endurance runners often exhibit an inadequate hyperventilatory response during intense exercise.
- Potential mechanisms include diminished hypoxic ventilatory responsiveness and ventilatory limitation due to maximal expiratory flow rates.
Purpose of the Study:
- To investigate if expiratory flow limitation affects the assessment of ventilatory responsiveness in elite runners.
- To determine the role of hypoxic ventilatory responsiveness (HVR) in oxygen saturation (SaO2) when expiratory flow limitation is considered.
Main Methods:
- Sixteen elite male runners were divided into flow-limited (FL) and non-flow-limited (NFL) groups based on expiratory flow-limitation during maximal exercise.
- Both groups underwent testing for hypoxic ventilatory responsiveness (HVR).
Main Results:
- No significant differences were found between FL and NFL groups in VO2max, maximal ventilation (VE max), or ventilatory equivalents (VE/VO2, VE/VCO2).
- A significant relationship between HVR and SaO2 was observed in the NFL group but not the FL group.
- Conversely, a significant relationship between VE/VO2 and SaO2 was found in the FL group but not the NFL group, indicating differing physiological responses between groups.
Conclusions:
- Expiratory flow limitation can influence the measurement of ventilatory responsiveness in elite athletes.
- When flow limitation is controlled, HVR plays a more critical role in determining exercise SaO2 in highly trained athletes than previously recognized.