MEASURES OF OXYGEN COST ARE NOT LINEARLY RELATED TO WORK RATE
Londeree, B. R., Moffitt-Gerstenberger, J., Padfield, J. A., & Lottmann, D. (1997). Oxygen consumption of cycle ergometry is nonlinearly related to work rate and pedal rate. Medicine and Science in Sports and Exercise, 29, 775-780.
The purpose of the study was to develop an equation to predict the oxygen cost of cycle ergometry.
Ss (N = 40) performed an incremental cycle ergometer test on three occasions at 50, 70, or 90 rpm in a counterbalanced order. Work rate was incremented every 5 or 6 min when steady rate values were achieved. To ensure accurate work rates, ergometer resistance was calibrated and flywheel revolutions were electronically measured. Oxygen consumption, the dependent variable, was measured with a computer-interfaced system that provided results every minute. Independent variables were work rate, pedal rate (rpm), weight (Kg), and gender.
It was concluded that the oxygen cost of cycle ergometry is nonlinearly related to work rate and pedal rate, linearly related to weight, and that females use less oxygen for a particular work rate than males.
Implication. The nonlinear relationship of cycle ergometry oxygen cost to work rate and pedal rate indicates that protocols used to assess reactions of the body to training might be in error where linear relationships are assumed. For example, in protocols used to determine ventilatory and lactate thresholds, an increased gradient of the curve related to work rate is the phenomenon that is of importance. It is possible that the work rates that are sampled merely reflect a curvilinear normal phenomenon rather than an actual deflection from one gradient of linearity to another.
Return to Table of Contents for this issue.