Influence of training status, age, and muscle fibre type on cycling efficiency and endurance performance
Participants
n=40 men in four groups: young trained cyclists, old trained cyclists, young untrained, old untrained (group sizes not given in the abstract).
Protocol
Incremental ramp test (peak VO₂, HRmax, maximal minute power); submaximal gross-efficiency (GE) test at a series of absolute and relative work rates and cadences; a 1-h cycling time trial in trained participants only; right vastus lateralis biopsy in all.
Key Findings
Both age and training status had significant main effects on GE at relative work rates (P < 0.01). The abstract does not say the age effect disappeared once training was controlled — it reports both effects.
% Type I fibres was higher in the trained groups (P < 0.01) and did not differ between age groups.
No relationship between fibre type and cycling efficiency at any work rate or cadence — the null that qualifies REF-484.
Fibre type did not influence cycling performance (stepwise regression, P > 0.05).
1-h time-trial power was predicted by average O₂ uptake (standardized β = 0.94) and GE (β = 0.34) — VO₂ was the stronger predictor, with some mathematical coupling acknowledged; of the GE measures, only GE at 120 rpm predicted performance.
Mechanism (proposed)
The abstract offers no mechanism for the GE differences beyond training status; motor-learning or pedalling-mechanics explanations are Inference, not tested here.
Practical Application
Hopker et al. 2013 (n=40 men, four groups): fibre type did not relate to cycling efficiency at any work rate or cadence, but training status and age both affected GE (P < 0.01); 1-h TT power was predicted by O₂ uptake (β 0.94) far more than by GE (β 0.34). Efficiency is not fixed by muscle fibre type — it goes with training status — but for a 1-h effort aerobic power still explains most of the result.
For masters athletes: training status matters for GE, and the trained-old group still had the trained type I profile; age itself also had an effect on GE in this sample, so "age does not touch efficiency" is not what the paper shows.
Inference, not tested: because fibre type did not explain GE, efficiency-directed training (cadence, technique, strength) is plausibly worthwhile regardless of a rider's fibre profile; the paper did not test an intervention.
Limitations
Cross-sectional, not longitudinal — does not show how fast GE adapts to a specific training stimulus; men only, n=40
Single muscle biopsy site
Recreational vs trained groups differ on many traits, so causal attribution to training status alone is conservative
How this entry was checked and changed
Why this level
regraded 2026-09-27 from B+: cross-sectional, n=40 (rubric: B+ needs ≥100 for a cross-sectional measurement study)
Content correction 2026-09-27
Level B+ -> B: cross-sectional, n=40. Tier widened to 0-3 (untrained groups included).
"Age effect on GE small or absent" -> the abstract reports significant main effects of BOTH age and training status on GE (P < 0.01); what age did not influence was fibre type.
"Performance tracked GE more strongly than VO₂max" -> reversed: O₂ uptake β = 0.94, GE β = 0.34; only GE at 120 rpm predicted performance. Added n=40, the four-group design and the type I difference by training status. Practical masters bullet rewritten accordingly. REF-444 byline 2018 -> 2012.