The study examined how work output and the components of energy expenditure (aerobic, anaerobic, and excess post‑exercise oxygen consumption – EPOC) differ between two consecutive bench‑press sets performed to muscular fatigue at three relative loads (70%, 80%, and 90% of one‑repetition maximum) in ten healthy young men. Work decreased in the second set for the 70% and 80% protocols but not for 90%. Anaerobic (glycolytic) energy expenditure was lower in the second set across all loads, while EPOC remained statistically similar across protocols and sets. Overall, aerobic expenditure was the smallest contributor, with anaerobic and EPOC accounting for the majority of total energy expenditure (TEE). The work‑to‑TEE ratio did not change within a protocol between sets, but the 90% protocol showed a significantly lower ratio, indicating higher energy cost per unit work. Correlations revealed that overall work was strongly linked to aerobic and anaerobic expenditures but not to EPOC. The authors conclude that, for resistance exercise, EPOC is relatively constant regardless of load, and that traditional models using a single oxygen uptake measure may misrepresent the true energy cost of anaerobic‑type training.
Topics
Experimental Protocol: Two‑Set Bench Press to Fatigue at Varying Relative Loads
Details of subject recruitment, 1RM determination, cadence control, measurement of work (J), oxygen uptake, blood lactate, and the three loading conditions (70%, 80%, 90% 1RM) across two consecutive sets performed to failure.
Work Output Patterns Across Loads and Sets
Quantitative findings that total work (J) decreased in the second set for 70% and 80% loads but remained unchanged for 90%, with significant differences among protocols (70% > 80% > 90%).
Energy Expenditure Partitioning: Aerobic, Anaerobic, and EPOC Contributions
Breakdown of energy costs showing aerobic expenditure as the smallest component, while anaerobic and EPOC dominate total energy expenditure; includes statistical comparisons and absolute values (kJ) for each component per protocol and set.
Constancy of EPOC Across Loading Protocols
Evidence that excess post‑exercise oxygen consumption (both duration and energy) did not differ significantly among 70%, 80%, and 90% protocols, despite large differences in work performed.
Work‑to‑Total Energy Expenditure Ratio as an Efficiency Metric
Analysis of the unitless work/TEE ratio, showing no intra‑protocol change between sets but a significantly lower ratio for the 90% protocol, indicating higher energetic cost per unit work at higher loads.
Methodological Insight: Blood Lactate‑Based Estimation of Anaerobic Energy
Explanation of how resting and peak blood lactate values were used to calculate glycolytic energy expenditure, and validation that a single post‑set lactate measure suffices for two‑set protocols.
Implications for Modeling Resistance‑Exercise Energy Expenditure
Discussion on why single‑measure oxygen uptake models may misrepresent anaerobic‑type exercise costs, emphasizing the need to account for anaerobic and EPOC components in energy balance calculations.