Selection criteria for exercise training in patients with COPD. 
The physical performance of patients with chronic obstructive pulmonary disease (COPD) is limited mainly by pathophysiological derangements of the ventilatory system.  Thus, the exercise performance can be ameliorated by increasing the level of ventilation that they can sustain, or by reducing the ventilatory requirement for a given level of activity.  Almost all studies have yielded negative results in COPD patients, in terms of exercise training having the ability to improve VEmax.  The only way to reduce the ventilatory requirement is to reduce CO2 output.  Lower levels of lactate result in less non-metabolic CO2 produced by bicarbonate buffering.  This is the likely mechanism responsible for a lower ventilatory requirement for work rates above the pre-training anaerobic threshold.  We specifically wished to determine, whether a program of intensity, frequency and duration known capable of producing a physiologic training effect in healthy subjects, would do so in COPD patients.  Further, we sought to determine, whether exercise training at a work rate associated with lactic acidosis is more effective in inducing a training effect in COPD patients than a work rate not associated with lactic acidosis.  Nineteen COPD patients were selected and performed an incremental test as well as two square wave tests at a low and a high work rate.  Identical tests were performed after an 8-week program of cycle ergometer training either for 45 min/day at a high work rate or for a proportionally longer time at a low work rate.(ABSTRACT TRUNCATED AT 250 WORDS)