REF-474 · Klaris et al., 2024 · Scandinavian Journal of Medicine & Science in Sports, · Paper · PubMed
Performance and Fatigue Patterns in Elite Cyclists During 6 h of Simulated Road Racing
Participants
n=12 male national elite cyclists (25 ± 3 y, 76 ± 6 kg, VO2max 5.2 ± 0.5 L/min).
Protocol
Laboratory incremental and maximal-fat-oxidation tests, then 6 h of simulated road racing with a peak sprint and a 5-km time trial after 0, 2, 4 and 6 h. Carbohydrate intake ~90 g/h.
Key Findings
Sprint: peak power fell from 1362 ± 176 W to 1271 ± 152 W after 2 h (p < 0.01) and then stabilised.
5-km TT: mean power declined gradually from 412 ± 38 W to 384 ± 41 W in the final trial; individual losses ranged 2-14%, and the loss was moderately related (r² = 0.45) to accumulated time above the lactate threshold.
Fuelling and metabolism: ~90 g/h carbohydrate maintained blood glucose; post-TT lactate fell from 15.1 ± 2 to 7.1 ± 2.3 mM, and fat oxidation rose from 0.7 ± 0.3 g/min at 0 h to 1.1 ± 0.1 g/min at 6 h.
The spread between athletes widened as the race went on.
Practical Application
In 12 national elite cyclists fuelling ~90 g/h through 6 h of simulated racing, sprint power dropped ~7% in the first 2 h and then held, while 5-km TT power fell steadily from 412 to 384 W (individual losses 2-14%), and the size of that loss tracked the time spent above lactate threshold — late-race sustained power is what erodes, and the hard minutes already spent predict how much.
For a long race: ration time above threshold early if the finish needs sustained power; a sprint finish is less exposed after the first couple of hours.
Fuelling at ~90 g/h kept blood glucose up in this study; it was not compared with a lower intake, so it cannot show how much the fuelling protected performance.
Not from this paper: whether fat-oxidation capacity still predicts durability under high carbohydrate intake — the abstract reports fat oxidation rising over 6 h but no association analysis. No entry in this base shows fat oxidation predicting durability (REF-196 did not analyse it in its abstract); see SYNTH-32 for the durability framework.
Limitations
Simulated racing, not actual competition; n=12, men only.
Observational — no control condition, single fuelling strategy (~90 g/h).
One 6-h format; generalisation to other durations is uncertain.
How this entry was checked and changed
Why this level
regraded 2026-09-27 from A-: observational, n=12
Content correction 2026-09-27
Headline "under high-CHO fuelling, fat oxidation rates were no longer associated with durability" -> not in the abstract; the abstract reports sprint power stabilising after 2 h, TT power falling 412 → 384 W with losses (2-14%) related to time above LT (r² = 0.45), and fat oxidation rising 0.7 → 1.1 g/min. The practical bullets built on the fat-oxidation claim were removed.
">90 g/h" -> ~90 g/h. Participants, test schedule and results added from the abstract.
Missing Tier and Sport lines added (Tier 3, cycling); Level A- -> B (observational, n=12); cross-reference REF-461 is Reynolds 2024, not Roberts.
Cross-reference descriptions checked against the cited entries' current content; wrong years, wrong entries and claims the cited entry does not make were corrected.
Durability claims re-checked against the corrected entries: REF-196 (Valenzuela 2022b) lost 2.9% on average with no relation to lab indicators and did not analyse fat oxidation in its abstract; REF-423 (Passfield & Doust 2000) ran no predictor analysis; REF-424 (Spragg) found the rested profile, VO2max included, positively related to durability. Statements attributing "fat oxidation r=+0.61", "−8.7%", or "VO2max did not predict" to these papers were corrected.
2026-10-01: cross-reference repointed from a merged framework to the one that replaced it (SYNTH-01→31, 05→34, 09→70, 12/15→32, 19→26).
2026-10-01: citation of the superseded pointer SYNTH-12 repointed to SYNTH-32, which carries the cited content.