European journal of applied physiology and occupational physiology
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Eur J Appl Physiol Occup Physiol · Aug 1998
Clinical TrialRegulating exercise intensity using ratings of perceived exertion during arm and leg ergometry.
The purpose of this investigation was to examine the validity of regulating exercise intensity using ratings of perceived exertion (RPEs) during arm crank and leg cycle exercise at 50 and 70% peak oxygen consumption (VO2peak). Ten men and seven women [26 (1) years old; mean (SE)] participated in this study. Each subject completed a maximal estimation trial and two submaximal exercise bouts (production trials) on both an arm and leg ergometer. ⋯ However, these two parameters were lower (P < 0.05) during the production trial [1.88 (0.15) l x min(-1) and 89.1 (10.1) W, respectively] as compared to the estimation trial [2.08(0.14) l x min(-1) and 102.4 (6.5)W, respectively] during leg ergometry at 70% VO2peak. In conclusion, using RPEs to regulate exercise intensity is physiologically valid during arm ergometry at both 50 and 70% VO2peak and during leg ergometry at 50% VO2peak. However, this prescriptive approach remains questionable during leg cycle exercise at 70% VO2peak.
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Eur J Appl Physiol Occup Physiol · Aug 1998
Clinical TrialSystemic oxygen extraction during incremental exercise in patients with severe chronic obstructive pulmonary disease.
To determine if decreased systemic oxygen (O2) extraction contributes to the exercise limit in severe chronic obstructive pulmonary disease (COPD), 40 consecutive incremental cycle ergometer exercise tests performed by such patients, from which a "log-log" lactate threshold (LT) was identified, were compared to those of 8 patients with left ventricular failure (LVF) and 10 normal controls. Pulmonary gas exchange and minute ventilation were measured continuously and arterial blood gas tensions, pH, and lactate concentrations were sampled each minute. Cardiac output (Qc) was measured by first-pass radionuclide ventriculography. ⋯ The systemic O2ER at peak exercise was severely reduced in COPD [0.36 (0.02)] compared to the other groups [P < 0.0001 for each], for whom it was nearly identical [0.58 (0.03) vs 0.63 (0.04), LVF vs control, P > 0.05]. In the COPD group, an early LT correlated with reduced systemic O2ER at peak exercise (r = 0.64, P < 0.0001), but not with any index of systemic O2 delivery. These data suggest that lactic acidemia during exercise in patients with severe COPD is better related to abnormal systemic O2 extraction than to its delivery and contributes to the exercise limit.