Key result
The upper region of moderate-intensity exercise (S2) significantly slowed the time constants of pulmonary oxygen uptake, leg blood flow, heart rate, and muscle deoxygenation compared with the lower region (S1) (P<0.05).
Why the study?
Does initiating exercise from a baseline of moderate-intensity exercise slow the kinetics of O2 uptake, leg blood flow, and muscle deoxygenation compared to initiating from a lower intensity?
Population
6 male subjects, mean age 23 (SD 4) years
Comparison
Two-legged, moderate-intensity, knee-extension… vs Two-legged, moderate-intensity, knee-extension…
Design
Other
Authors
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Small-sample (n=6) physiology data on exercise-onset kinetics; leaves open whether single- or multistep transitions better inform clinical testing.
Does initiating exercise from a baseline of moderate-intensity exercise slow the kinetics of O2 uptake, leg blood flow, and muscle deoxygenation compared to initiating from a lower intensity?
p-value: p=<0.05
The slowed Vo2 response when exercise is initiated from a moderate-intensity baseline suggests Vo2 kinetics are limited by slowed adaptation of blood flow and/or O2 transport.
MacPhee et al. (2005) studied this question. Upper region of moderate-intensity exercise (S2: ~45% to ~90% estimated lactate threshold) vs. Lower region of moderate-intensity exercise (S1: 3 W to ~45% estimated lactate threshold) was evaluated on Time constants (tau) of pulmonary oxygen uptake (Vo2), leg blood flow (LBF), heart rate (HR), and muscle deoxygenation (HHb) (p=<0.05). The upper region of moderate-intensity exercise (S2) significantly slowed the time constants of pulmonary oxygen uptake, leg blood flow, heart rate, and muscle deoxygenation compared with the lower region (S1) (P<0.05).
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