Energy cost calculations for exercise prescription - An update

Recent research has resulted in a number of recommended changes in how fitness professionals should prescribe target workloads and calculate the energy cost of exercise. The principal changes are in the use of oxygen consumption reserve ((V)over dot(2)R) as an alternative to percentage of maximal oxygen consumption ((V)over dot O(2)max for prescribing exercise intensity, the use of net (V)over dot O-2 rather than gross (V)over dot O-2 for the calculation of caloric expenditure during exercise, and a modification of the American College of Sports Medicine (ACSM) equation for calculating the oxygen cost of leg cycle ergometry. The (V)over dot O2R method of prescribing exercise workloads is similar to the heart rate reserve (HRR) method of prescribing target heart rates, i.e. the target workload is established at a given percentage of the difference between maximal and resting (V)over dot O-2. Several recent studies have shown that there is a discrepancy between the exercise intensity at given percentages of HRR and (V)over dot O(2)max but that HRR and (V)over dot O2R yield equivalent exercise intensities. The use of (V)over dot O2R in exercise prescription provides more accurate target workloads, especially for individuals with a low fitness level. Net (V)over dot O-2 during exercise is that amount above resting (V)over dot O-2 due to the exercise itself. A recent recommendation is to employ net (V)over dot O-2 in the calculation of the caloric expenditure during exercise, so as not to overestimate potential bodyweight loss. Several recent studies of leg cycling ergometry have yielded equations for the estimation of (V)over dot O-2 that include a term for unloaded cycling, i.e. the oxygen cost of moving the legs against zero resistance. The equations from these studies provide more accurate estimations of cycling (V)over dot O-2 than the existing ACSM equation, and a new standardised equation has been developed and adopted by the ACSM. The new equation is especially useful for improving the accuracy of (V)over dot O-2 estimates during low intensity leg cycle ergometry. The ACSM equation for bench stepping has also been modified to include a term for resting metabolism.