• Publications
  • Influence
The level and tempo of children's physical activities: an observational study.
We develop an observation system that quantifies the duration, intensity, and frequency of children's physical activities. We use this system to assess the level and tempo of energy expenditure underExpand
  • 896
  • 55
Linear and nonlinear characteristics of oxygen uptake kinetics during heavy exercise.
We assessed the linearity of oxygen uptake (VO2) kinetics for several work intensities in four trained cyclists. VO2 was measured breath by breath during transitions from 33 W (baseline) to workExpand
  • 426
  • 39
Influence of muscle fiber type and pedal frequency on oxygen uptake kinetics of heavy exercise.
We tested the hypothesis that the amplitude of the additional slow component of O2 uptake (VO2) during heavy exercise is correlated with the percentage of type II (fast-twitch) fibers in theExpand
  • 457
  • 34
Oxygen Uptake Kinetics in Treadmill Running and Cycle Ergometry: A Comparison.
The purpose of the present study was to comprehensively examine oxygen consumption (VO(2)) kinetics during running and cycling through mathematical modeling of the breath-by-breath gas exchangeExpand
  • 218
  • 27
  • Open Access
The slow component of O2 uptake is not accompanied by changes in muscle EMG during repeated bouts of heavy exercise in humans
1 We hypothesized that either the recruitment of additional muscle motor units and/or the progressive recruitment of less efficient fast‐twitch muscle fibres was the predominant contributor to theExpand
  • 189
  • 25
  • Open Access
Influence of work rate on ventilatory and gas exchange kinetics.
A linear system has the property that the kinetics of response do not depend on the stimulus amplitude. We sought to determine whether the responses of O2 uptake (VO2), CO2 output (VCO2), andExpand
  • 168
  • 20
Modulation of muscle and pulmonary O2 uptakes by circulatory dynamics during exercise.
The effect of cardiovascular adjustments on the coupling of cellular to pulmonary gas exchange during unsteady states of exercise remains controversial. Computer simulations were performed to assessExpand
  • 260
  • 18
Control of oxygen uptake during exercise.
Other than during sleep and contrived laboratory testing protocols, humans rarely exist in prolonged metabolic steady states; rather, they transition among different metabolic rates (V O2). TheExpand
  • 202
  • 17
Kinetics of oxygen uptake during supine and upright heavy exercise.
It is presently unclear how the fast and slow components of pulmonary oxygen uptake (VO(2)) kinetics would be altered by body posture during heavy exercise [i.e., above the lactate threshold (LT)].Expand
  • 113
  • 17
  • Open Access
Muscle energetics and pulmonary oxygen uptake kinetics during moderate exercise.
The present study tested whether, during moderate exercise, 1) the dynamic responses of ADP and changes in free energy of ATP hydrolysis (delta GATP) were similar to those of phosphocreatine [PCr; asExpand
  • 174
  • 16