Cardiovascular Fitness and Energy Expenditure Response during a Combined Aerobic and Circuit Weight Training Protocol

Abstract

Objectives: The 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.

Design: Controlled, randomized crossover designs.

Methods: Subjects 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.

Results: Energy 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).

Conclusions: In 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 registration: ClinicalTrials.gov NCT01116856.

Fig 1. Exercise protocol.

Circuit Machine training protocol, Free Weight-training protocol and Combined Exercise training protocol, all with the same duration, intensity, cadence, etc.

Fig 2. Blood lactate concentration measurements (mmol·L^-1) during training protocols.

CM: Circuit Machine training protocol; FW: Free Weight-training protocol; CE: Combined Exercise training protocol. Data are reported as mean ± SEM for women (n = 14) and men (n = 15). ^a p<0.05 with CM. ^b p<0.05 with FW.

Fig 3. Net energy expenditure (Kcal) in men (n = 15) and women (n = 14) during the entire circuit weight training protocol.

Percentages represent the individual contribution of aerobic energy expenditure (grey) and anaerobic energy expenditure (black) to total energy expenditure. CM: Circuit Machine training protocol; FW: Free Weight-training protocol; CE: Combined Exercise training protocol. ^a p<0.05 with CM, ^b p<0.05 with FW, ** p<0.001 aerobic energy expenditure with total energy expenditure (aerobic + anaerobic) (P<0.001), ^# p = 0.06 with CM.