Reliability of cardiopulmonary exercise measures and their response to endurance training in older patients with coronary disease

This study assessed the test-retest reliability of cardiopulmonary variables measured during treadmill exercise in older patients with coronary disease and determined whether a component of the change in these variables attributed to endurance training is related to habituation to the exercise test. Twenty-three coronary patients (mean age 68.8 ± 6.2 years) underwent a 12-week endurance training program. Exercise tests to exhaustion were performed at the same time in the morning twice before (separated by less than 1 week) and once after conditioning. At rest, all hemodynamic measurements were reliable. During submaximal exercise (approximately 3 metabolic units [METS]), only systolic blood pressure was reliably measured, whereas measurements of heart rate, oxygen consumption, ventilation, and respiratory exchange ratio were unreliable. At maximal exercise, systolic blood pressure, heart rate multiplied by systolic blood pressure, and respiratory exchange ratio were reliably measured, whereas measurements of heart rate, oxygen consumption, ventilation, and exercise duration were unreliable. Endurance training increased (P < 0.01) exercise duration and maximal oxygen consumption by 6 minutes and 4.1 ml/kg/min, respectively, of which approximately 18% and 24% (1.1 minutes and 1.0 ml/kg/min) were attributable to habituation to the exercise test. Thus, administration of only one treadmill test to assess baseline cardiopulmonary fitness of older patients with coronary disease is inadequate because most measurements are unreliable and the magnitude of improvement from endurance training is exaggerated.