M Jetté

One metabolic equivalent (MET) is defined as the amount of oxygen consumed while sitting at rest and is equal to 3.5 ml O2 per kg body weight x min. The MET concept represents a simple, practical, and easily understood procedure for expressing the energy cost of physical activities as a multiple of the resting metabolic rate. The energy cost of an activity can be determined by dividing the relative oxygen cost of the activity (ml O2/kg/min) x by 3.5. This article summarizes and presents energy expenditure values for numerous household and recreational activities in both METS and watts units. Also, the intensity levels (in METS) for selected exercise protocols are compared stage by stage. In spite of its limitations, the MET concept provides a convenient method to describe the functional capacity or exercise tolerance of an individual as determined from progressive exercise testing and to define a repertoire of physical activities in which a person may participate safely, without exceeding a prescribed intensity level.

BACKGROUND: This study was designed to determine the controlled effects of a short-term exercise rehabilitation program on patients with moderate-to-severe left ventricular dysfunction after a recent myocardial infarction. METHODS AND RESULTS: Thirty-nine male patients 51 +/- 8 years old with a large anterior myocardial infarction less than 10 weeks old were recruited for the study. The patients were randomly assigned to either one of two training or control groups on the basis of their resting ejection fraction: training, less than 30%; control, less than 30%; training, 31-50%; or control, 31-50%. Patients were evaluated for filling pressures, radionuclide ventriculography, heart volume, echocardiography, and work capacity. Patients who underwent training participated in an intensive 4-week in-hospital exercise program, whereas the control patients were restricted to a minimal activity program. Results indicated that there were no significant improvements in resting, submaximal, and maximal hemodynamic measurements as a result of the program. Mean work capacity and peak oxygen consumption improved significantly in the less-than-30% training group but was accompanied by a significant increase in mean pulmonary wedge pressure. Resting ejection fraction improved markedly in both less-than-30% training and control patients, but ejection fraction measures were not associated with work capacity. Training did not cause further deterioration in ventricular function. CONCLUSIONS: It was concluded that in the present study, exercise training had little or no effect on hemodynamic measurements and that the training effects achieved in patients with left ventricular dysfunction are most likely due to corrected impaired vasodilation, not necessarily to cardiac function. The importance of using a control group in this type of study and the wide interindividual variations in training responses are emphasized.

Le but de cet article est double: determiner les effets d'un programme d'entrainement de 12 semaines sur le rendement d'indices de travail et cardiovasculaires chez des hommes et des femmes sedentaires d'âge moyen, et comparer une procedure de laboratoire pour prescrire un programme individuel de marche/jogging qui utilise le pourcentage de VO 2 max selon le poids et la taille. Il est conclut qu'une prescription d'exercice basee sur une allure de marche appropriee, est une procedure simple et efficace pour mettre en valeur les aptitudes cardiorespiratoires d'hommes et de femmes sedentaires d'âge moyen

The purpose of this study was to compare the predicted maximal oxygen concumption derived from the Canadian Home Fitness Test (CHFT) and the Astrand ergometer test to the observed VO2 max determined from a progressive multi-stage treadmill test. Sixty-four sedentary subjects (35 males and 29 females) ranging in age from 20 to 54 years participated in the study. The mean VO2 max measured on the treadmill for males and females was 34.6 +/- 6.0 ml/kg/min while the Astrand procedure predicted a mean VO2max of 29.6 +/- 6.5 ml/kg/min and the CHFT predicted a mean VO2 max of 34.8 +/- 5.0 ml/kg/min. Statistical analysis revealed a significant under-prediction (P less than 0.001) of the VO2 predicted by the Astrand test to the VO2 max derived from the treadmill test while there were no differences between the treadmill VO2max and that predicted by the CHFT. When the male and female values were analyzed separately, the same results were seen in the males. For the females, however, there were no significant differences among predicted and observed values. It concluded that the CHFT provided an adequate prediction of cardio-respiratory fitness as well as, if not superior to, the Astrand procedure.