Late-ride power fade is driven by multiple mechanisms at once, not a single cause like glycogen depletion
Interpretation
Central fatigue (the nervous system reducing motor drive before muscles actually fail) measurably contributes to late-exercise power loss, as does rising oxygen cost for the same power and substrate-level changes — not just an empty glycogen tank. Even well-fuelled elite cyclists still lose power late in prolonged efforts.
Practical implication
Don't diagnose late-ride fade purely as a fuelling failure. A durability-training program should address pacing discipline and progressive fatigue exposure, not just carbohydrate intake.
Sources
3 sources, independently verified.
Volume 586(Pt 1):161-173 (the source article cited this as 2008 — actual publication year is 2007, corrected here). Cyclists performed constant-workload prefatigue trials at 83% and 67% of peak power. Found feedback from fatiguing muscle regulates central motor drive — direct evidence for the 'brain backs off before muscle fails' central-fatigue mechanism.
Two 33-min trials at identical average power — one constant (70% max aerobic power), one variable (alternating high/moderate). Neuromuscular fatigue was greater after the variable-power trial despite identical average power, directly supporting the 'surges cost more than steady riding at the same average' principle.
4-hour intermittent cycling protocol with 100 g/h carbohydrate intake; peak and mean 6-min TT power fell 10% and 6% respectively afterward. Crucially, the magnitude of decline could NOT be predicted from fresh-state lab measures — direct evidence that fresh-state testing alone can't predict durability.