Abstract
ObjectivesThe present study describes the oxygen uptake and total energy expenditure (including both aerobic and anaerobic contribution) response during three different circuit weight training (CWT) protocols of equivalent duration composed of free weight exercises, machine exercises, and a combination of free weight exercises intercalating aerobic exercise.DesignControlled, randomized crossover designs.MethodsSubjects completed in a randomized order three circuit weight training protocols of the same duration (3 sets of 8 exercises, 45min 15s) and intensity (70% of 15 repetitions maximum). The circuit protocols were composed of free weight exercises, machine exercises, or a combination of free weight exercises with aerobic exercise. Oxygen consumption and lactate concentration were measured throughout the circuit to estimate aerobic and anaerobic energy expenditure respectively.ResultsEnergy expenditure is higher in the combined exercise protocol (29.9±3.6 ml/kg/min), compared with Freeweight (24.2±2.8ml/kg/min) and Machine (20.4±2.9ml/kg/min). The combined exercise protocol produced the highest total energy expenditure but the lowest lactate concentration and perceived exertion. The anaerobic contribution to total energy expenditure was higher in the machine and free weight protocols compared with the combined exercise protocol (6.2%, 4.6% and 2.3% respectively).ConclusionsIn the proposed protocols, the combined exercise protocol results in the highest oxygen consumption. Total energy expenditure is related to the type of exercise included in the circuit. Anaerobic contributions to total energy expenditure during circuit weight training may be modest, but lack of their estimation may underestimate total energy expenditure.Trial RegistrationClinicalTrials.gov NCT01116856
Highlights
Cardiorespiratory fitness is a powerful predictor of future health in people of all ages and gender, regardless of pre-existing health conditions [1]
Total energy expenditure is related to the type of exercise included in the circuit
Current needs for further research include to design intervention studies to accurately compare the effects on different health outcomes and weight loss of aerobic exercise with those from resistance exercise, or a combination of both
Summary
Cardiorespiratory fitness is a powerful predictor of future health in people of all ages and gender, regardless of pre-existing health conditions [1]. Current needs for further research include to design intervention studies to accurately compare the effects on different health outcomes and weight loss of aerobic exercise with those from resistance exercise, or a combination of both For these comparisons to be accurate, it is necessary to design exercise programs that are equivalent in energy expenditure (EE); otherwise, different effects could just result from different EE. This is challenging when comparing aerobic exercise such as running on a treadmill, with resistance training, since the latter may have an important anaerobic component which contributes to total EE. This anaerobic contribution is usually ignored in EE estimations, leading to an overall underestimation of the actual EE of a given exercise
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