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Lactate acidosis and the increase in VE/VO2 during incremental exercise
Journal of Applied Physiology (Bethesda, Md. : 1985)
|April 1, 1987
Summary
Lactate acidosis does not cause the rise in the ventilatory equivalent (VE/VO2) during intense exercise. This study found that VE/VO2 increased at similar exercise intensities, even when blood pH was lowered by lactate accumulation.
Area of Science:
- Exercise Physiology
- Sports Medicine
- Biochemistry
Background:
- The ventilatory equivalent for oxygen uptake (VE/VO2) increases during incremental exercise.
- Lactate accumulation and subsequent blood pH decrease are associated with high-intensity exercise.
Purpose of the Study:
- To investigate if lactate acidosis is the cause of the increased VE/VO2 during incremental exercise.
- To differentiate the effects of exercise intensity from blood pH on VE/VO2.
Main Methods:
- Maximal incremental exercise tests were performed on a cycle ergometer by eight male subjects.
- Two conditions were tested: a control (C) and an experimental (E) condition where blood lactate was elevated before exercise.
- Venous blood samples (pH, lactate) and ventilatory parameters were monitored throughout the tests.
Main Results:
- The increase in VE/VO2 occurred at comparable work rates and %VO2max in both C and E conditions.
- Venous H+ and lactate concentrations were significantly higher during the E treatment.
- Despite elevated lactate and lower pH in E, the VE/VO2 response pattern remained similar to C.
Conclusions:
- Decreased blood pH due to lactate accumulation is not the primary driver for the increase in VE/VO2 during incremental exercise.
- Other factors likely contribute to the rise in VE/VO2 at higher exercise intensities.