In 13 well-trained cyclists and triathletes, 150 min of moderate riding cut VT1 power by 6% and 5-min TT power by 9%, and riders whose VT1 held up lost less TT power (rs = 0.72)
While durability was not related to muscle carnosine, citrate synthase or complex I activity
Participants
n=13 well-trained cyclists and triathletes (VO2peak 57.3 ± 4.8 ml/kg/min; training 12 ± 2.1 h/week).
Protocol
On separate days: an incremental test (power at the first ventilatory threshold, VT1) and a 5-min time trial, each with and without 150 min of prior moderate-intensity cycling. A single resting vastus lateralis microbiopsy for carnosine content, citrate synthase and complex I activity.
Key Findings
Prolonged exercise reduced VT1 power from 211 ± 40 to 198 ± 39 W (−13 ± 16 W, −6 ± 7%, P = 0.013) and 5-min TT power from 333 ± 75 to 302 ± 63 W (−31 ± 41 W, −9 ± 10%, P = 0.017).
The loss of 5-min TT power was associated with the durability of VT1 (rs = 0.719, P = 0.007): more durable riders lost less.
Durability of VT1 was not related to vastus lateralis carnosine content, citrate synthase activity or complex I activity.
Practical Application
After 150 min of moderate riding, 13 well-trained cyclists lost ~6% of VT1 power and ~9% of 5-min power, and the riders whose VT1 held up best lost the least 5-min power (rs = 0.72) — durability of the first threshold is a performance parameter in its own right (Hamilton 2024).
Muscle oxidative markers (citrate synthase, complex I) and carnosine did not predict durability here — test it directly, after a long ride, rather than inferring it from a fresh profile.
Limitations
n=13, one fatiguing protocol (150 min moderate), one short performance test.
Correlational; a single resting biopsy.
Full text not read; everything above is from the abstract.
How this entry was checked and changed
Why this level
small within-subject study (n=13)
Content correction 2026-09-27
Anchored to Hamilton et al. 2024, EJAP 124(8):2427-2438, DOI 10.1007/s00421-024-05459-6 (author, year, journal, biopsy design and the null enzyme result match). Identified by a title/topic search and attached with the owner's explicit OK (2026-09-27).
Corrected against the abstract: n=23 -> 13; "trained amateur males" -> well-trained cyclists and triathletes; enzymes β-HAD/SDH/COX -> carnosine, citrate synthase and complex I; "glycogen-depleting ride" -> 150 min moderate; added the VT1 (−6%) and 5-min TT (−9%) results and the rs = 0.72 link. The claim of no correlation with rested VO2max/GE is not in the abstract and was removed. Level C+ -> B.
Two cross-references unrelated to the paper (REF-117 low cadence, REF-157 pre-exercise meals) were removed.
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.