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Catecholamine and blood lactate responses to incremental rowing and running exercise
A Weltman1, C M Wood, C J Womack
1Exercise Physiology Laboratory, Curry School of Education, University of Virginia, Charlottesville 22903.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|March 1, 1994
Summary
Lactate threshold (LT) occurs at lower oxygen uptake (VO2) than epinephrine and norepinephrine thresholds during both rowing and running exercise. This suggests that catecholamine thresholds do not directly cause LT, though epinephrine levels at LT are consistent with lactate release.
Area of Science:
- Exercise Physiology
- Sports Science
- Human Performance
Background:
- Understanding the physiological triggers for lactate threshold (LT) is crucial in exercise science.
- Catecholamines, such as epinephrine and norepinephrine, are known to influence metabolic responses during exercise.
- The relationship between catecholamine release and lactate accumulation requires further investigation across different exercise modalities.
Purpose of the Study:
- To compare lactate threshold (LT) with epinephrine threshold (Epi-T) and norepinephrine threshold (NE-T) during incremental rowing and running exercise.
- To determine if catecholamine thresholds precede or coincide with LT in collegiate rowers.
- To examine the plasma concentrations of epinephrine and norepinephrine at LT for different exercise modes.
Main Methods:
- Ten collegiate rowers underwent discontinuous incremental exercise tests on both a rowing ergometer and a treadmill.
- Ventilation, pulmonary gas exchange (VO2), blood lactate ([La]), plasma epinephrine ([Epi]), and norepinephrine ([NE]) were continuously monitored.
- Lactate threshold (LT), Epi-T, and NE-T were identified as breakpoints in VO2 plots.
Main Results:
- LT occurred at a significantly lower VO2 than both Epi-T and NE-T during both running and rowing.
- For running, LT (3.76 L/min) < NE-T (4.04 L/min) < Epi-T (4.35 L/min); for rowing, LT (3.35 L/min) < NE-T (3.70 L/min) ≈ Epi-T (3.72 L/min).
- Plasma epinephrine concentrations at LT were similar across both exercise modes (rowing: 221 pg/ml, running: 245 pg/ml), while plasma norepinephrine at LT differed significantly.
Conclusions:
- Catecholamine thresholds do not appear to be the direct cause of the lactate threshold during incremental exercise in rowers.
- The observed plasma epinephrine levels at LT are consistent with those known to stimulate lactate release.
- Differences in plasma norepinephrine at LT between rowing and running suggest mode-specific sympathoadrenal responses.