Energy Expenditure Before, During, and After the Bench Press

We examined the reliability and validity of non-steady-state aerobic and anaerobic estimations of energy expenditure during and after bouts of the bench press exercise. A Smith machine, not free weights, was used. On different days, 8 subjects (28.4 +/- 9.0 years; 170.4 +/- 11.9 cm; 68.4 +/- 14.0 kg) were randomly assigned to 3 lifting sessions of 7, 14, and 21 reps at 50% of the 1-repetition maximum (9 total sessions). No differences were found in any of the triplicate measures within 7, 14, and 21 reps. Coefficients of variation for 7, 14, and 21 reps were, respectively, for resting blood lactate, 20.3, 24.3, and 26.7%; for anaerobic exercise energy expenditure, 47.9, 29.1, and 14.2%; for aerobic exercise energy expenditure, 47.4, 28.3, and 18.4%; for excess postexercise O2 consumption, 33.0, 26.5, and 29.2%; for total energy expenditure, 21.0, 15.4, and 15.1%; and, for work, 4.5, 5.0, and 5.4%. Anaerobic energy expenditure made a significant contribution to exercise energy expenditure for all lifts (p < 0.05). Changes (Delta) in work were related to changes in energy expenditure (Delta aerobic exercise energy expenditure, r = 0.54; Delta anaerobic exercise energy expenditure, r = 0.88; Delta total energy expenditure, r = 0.88; p < 0.001). Although variability is evident and often considerable during exercise and recovery in this heterogonous sample, we suggest that non-steady-state estimates of aerobic and anaerobic exercise energy expenditure with excess postexercise O2 consumption provide a reasonable estimate of the energy cost of a single bout of weight lifting. Our results agree with those of others, without the need for multiple steady-state measurements or for the assumption of proportional increases between work and O2 uptake.