Purpose: To determine the change in muscular efficiency in world-class professional cyclists during years of training/competition. Methods: Twelve male world-class professional road cyclists (mean +/- SD: age = 22.6 +/- 3.8 yr and VO2max = 75.5 +/- 3.3 mL/kg.min) performed an incremental test (starting at 100 W with workload increases of 50 W every 4-min interval until volitional exhaustion) before and after a five-season period. Delta efficiency (DE) was calculated from 100 W to that power output (PO) in which the RER was 1. Results: DE increased (P < 0.01) from 23.61 +/- 2.78% to 26.97 +/- 3.7% from the first to the fifth year, whereas VO2max showed no significant increase. A significant inverse correlation (r = -0.620; P = 0.032) between DE and VO2max (mL/kg.min) was found in the fifth year, whereas no significant correlation between these variables was found in the first year. A significant inverse correlation (r = -0.63; P = 0.029) was found between the increase percentage in DE ([DELTA]DE) and VO2max (mL/kg.min) in the fifth year, whereas no significant correlation was found between these variables in the first year. Conclusion: The results show an increase in DE in world-class professional cyclists during a five-season training/competition period, without significant variations in V2max. The results also suggest that the increase in DE could be a possible way for performance compensation, especially in those subjects with lower VO2max.
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