title: Oxygen uptake, heart rate, and ratings of perceived exertion at the PWCVo2.
abstract: The purpose of the present study was to examine the oxygen uptake (Vo2), heart rate (HR), and ratings of perceived exertion (RPE [OMNI-Leg 0-10]) responses during continuous 1-hour cycle ergometer rides at the PWCVo2 (physical working capacity at the oxygen consumption threshold). Eight subjects (mean age +/- SD = 23 +/- 3.2 years) performed a maximal test to exhaustion for the determination of Vo2peak and ventilatory threshold (VT). The subjects also performed 4 randomly ordered 8-minute workbouts at different power outputs (ranging from 84 to 245 W) to determine the PWCVo2 and a continuous 1-hour cycle ergometer ride at the PWCVo2 during which Vo2, HR, and RPE data were collected every 2 minutes. The PWCVo2 (114 +/- 39 W) and VT (133 +/- 44 W) were not significantly different and occurred at 56 and 63% Vo2peak, respectively. Linear regression showed that the slope coefficients for the Vo2, HR, and RPE vs. time relationships for the continuous 1-hour workbouts were significantly greater than zero. Furthermore, a t-test about a single mean indicated that the mean slope coefficient for the HR vs. time relationship was significantly greater than 0.1 bpm x min(-1) (the rate of increase in HR that can be maintained for an 8-hour day). The results of this study indicated that PWCVo2 could be maintained for an extended period. However, the maximal power output associated with steady state Vo2, HR, and RPE responses was overestimated. The mean increase in Vo2 during the continuous 1-hour ride was 270 mL, which suggested that the PWCVo2 may demarcate the moderate from heavy exercise domains. The mean HR slope coefficient of 0.3 bpm x min(-1) indicated that the power output at the PWCVo2 could likely be maintained for greater than 2 hours.
authors.affiliation: Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska, USA. mmielke@unlserve.unl.edu
authors.forename: Michelle
authors.initials: M
authors.lastname: Mielke
authors.forename: Terry J
authors.initials: TJ
authors.lastname: Housh
authors.forename: C Russell
authors.initials: CR
authors.lastname: Hendrix
authors.forename: Clayton L
authors.initials: CL
authors.lastname: Camic
authors.forename: Jorge M
authors.initials: JM
authors.lastname: Zuniga
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Schmidt
authors.forename: Glen O
authors.initials: GO
authors.lastname: Johnson
mesh_terms: D000704:Analysis of Variance; D004576:Electromyography; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology; D055815:Young Adult