Introduction - This study was conducted to attempt to identify a decrease in oxygen uptake ((V) over dotO(2)) at the end of a constant running exercise at 95% of maximal aerobic speed in trained athletes.
Synthesis of results - With reference to the classical 3th phases describing the oxygen uptake ((V) over dotO(2)) kinetics, a 4th phase characterized by a significant decrease in (V) over dotO(2) before exhaustion (p < 0.01) was identified in seven out of 13 of the subjects during 13.8 +/- 7.8% of time to exhaustion.
Conclusion - During the exercise, a reduction in tidal volume and an increase in respiratory frequency were observed for these seven subjects indicating that the likely physiological factor involved in the (V) over dotO(2) decrease could be the fatigue of respiratory muscles.