REF-1003 · Santalla et al., 2009 · Medicine & Science in Sports & Exercise, Vol. · Paper · PubMed

Muscle efficiency improves over time in world-class cyclists

Blimited evidenceMeasured on world-class athletesWritten before October 2026, being re-checked

Twelve male world-class professional road cyclists performed an incremental test before and after a five-season period of training and competition. Delta efficiency (DE), calculated from 100 W to the power output at which RER was 1, increased significantly from the first to the fifth year, whereas VO2max showed no significant increase.

In the fifth year, but not the first, DE was inversely correlated with VO2max, and the percentage increase in DE was inversely correlated with VO2max. The authors suggest the increase in DE could be a way of performance compensation, especially in riders with lower VO2max.

Participants

Twelve male world-class professional road cyclists (mean ± SD: age 22.6 ± 3.8 yr; VO2max 75.5 ± 3.3 mL·kg⁻¹·min⁻¹).

Protocol

Incremental test starting at 100 W with workload increases of 50 W every 4-min interval until volitional exhaustion.
Performed before and after a five-season period.
Delta efficiency calculated from 100 W to the power output at which RER was 1.

Key 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.
Fifth year: significant inverse correlation between DE and VO2max (r = -0.620; P = 0.032); no significant correlation in the first year.
Fifth year: significant inverse correlation between the increase percentage in DE and VO2max (r = -0.63; P = 0.029); no significant correlation between these variables in the first year.

Practical Application

"If VO2max is already at its ceiling, what still improves?" In twelve world-class professional cyclists (VO2max 75.5) tested before and after five seasons (within-person change, no control), delta efficiency rose from 23.61 to 26.97% while VO2max showed no significant increase, and riders with lower VO2max were the ones with the larger efficiency gain (r = -0.63). At this level the engine was flat and efficiency moved.
What was measured: delta efficiency and VO2max from an incremental test. What was not: performance, training content, gross efficiency, threshold power.
The inverse relation is between riders at one time point and between the gain and VO2max; it does not show that raising one lowers the other within a rider.
Inference, not tested here: for an athlete far below this level, VO2max is not yet at a ceiling, so this pattern does not make efficiency the first lever.
A group result on the question that REF-077 addressed with a single rider.

Limitations

Uncontrolled; n=12; two test points five seasons apart.
Riders started at 22.6 years, so maturation and training cannot be separated.
Delta efficiency is sensitive to how it is calculated; no performance outcome and no training data in the abstract.
Men only, world-class professionals.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

uncontrolled pre-post, n=12, elite series

Content correction 2026-09-27
2026-10-02: aligned with the rewritten SYNTH-42 (missing stimulus, one lever per block, level C+): cross-reference description — SYNTH-42 uses this entry for within-athlete change over seasons, not for what separates athletes.