Resistance exercise energy expenditure is greater with fatigue as compared to non-fatigue

We retrospectively investigated data from two separate studies to estimate and compare aerobic and anaerobic exercise energy expenditure (EE) along with the aerobic recovery EE component for 1-set of resistance exercise. One study was completed using non-fatiguing lifts where the exercise was stopped before muscular failure. In another study muscular failure (fatigue) was the end point of all lifts. Work (weight lifted × upward vertical displacement) and all EE components were examined. Non-fatiguing lifts were carried out at 50% of a 1-RM for 7, 14 and 21 repetitions. Lifts to failure were carried out at ~37%, ~46%, ~56%, 70%, 80% and 90% of a 1-RM. Individual regression lines were created for fatigue and non-fatigue conditions for each male subject between work and all estimates of EE. The results of our analyses showed that the averaged slopes between fatigue and non-fatigue were proportional for: total EE/work (p = 0.87), anaerobic exercise EE/work, (p= 0.73) and recovery EE/work (p = 0.19). However, the Y-intercepts of the two studies were significantly greater for fatiguing as compared to non-fatiguing lifting for: total EE/work (p = 0.007), anaerobic exercise EE/work (p = 0.001) and recovery EE/work (p = 0.01), but not aerobic exercise EE/work (p = 0.17). For aerobic exercise EE/work, lifting to fatigue had a greater O2 uptake/work slope as compared to lifts that were not completed to fatigue (p = 0.04). We conclude that lifting a weight to muscular failure can entail significantly greater aerobic, anaerobic and recovery EE components as compared to non-fatiguing lifting.