Abstract des Autors

A metabolic equivalent (MET) is defined as the amount of oxygen consumed while sitting at rest, and it represents a practical way of expressing the energy cost of physical activities as a multiple of the resting metabolic rate. For this reason, it is widely used to recommend and prescribe physical exercise. For example, currently, at least 150 min/week of moderate-intensity exercise (3–6 METs), 75 min/week of vigorous-intensity exercise (6–9 METs), or an equivalent combination of the two is recommended to improve a person’s health. In this sense, cardiorespiratory fitness (CRF) is one of the most important objectives related to physical exercise to control and prevent several diseases (it decreases the risk of developing coronary heart disease, stroke, type 2 diabetes, some forms of cancer, etc.). CRF is a health-related component of physical fitness and is usually measured by exercise tolerance testing. CRF is defined as the ability of the circulatory, respiratory, and muscular systems to supply oxygen during sustained physical activity, and is expressed in METs or maximal oxygen uptake (VO2max). An increase in CRF (~1 METs) has been associated with a reduction of 13% and 15% in overall mortality and cardiovascular disease, respectively. This increase in CRF has proven to be independent of classic risk factors (waist circumference, body mass index, etc.). Depending on fitness level, any type of physical activity could induce improvements in CRF. As Powell et al. stated, ‘Some activity is better than none, and more is better than some’, to a certain extent. Even light-intensity activity appears to provide benefits and is preferable to sitting still, and this is often better for people who are unable to perform high-intensity exercise. Thus, both volume and intensity are important factors in reducing the risk of cardiovascular diseases and increasing CRF. Thus, the main goal of personalized preventive medicine is to recommend an efficient dosage of exercise that is capable of generating greater physiological benefits for the person (e.g. CRF) with the lowest health risks and the shortest possible time requirement. In this sense, controlling the intensity of exercise is very important. In relation to the aforementioned, there are several indicators of training intensity, including VO2max, VO2 reserve (VO2R), maximum heart rate (MHR), heart rate reserve (HRR), anaerobic threshold, aerobic threshold, METs, blood lactate concentration, and rating of perceived exertion. However, although all the indicators mentioned above are linked to a physiological or metabolic response, only METs are typically prescribed in a manner other than as a percentage of the maximum capacity of work (MCW) of the person (relative indicator). For example, a person may be instructed to exercise at 65% of their MHR or 80% of their VO2R. Therefore, certain situations should be considered when prescribing exercise using METs, both to protect and to improve a person’s health.