Faster V̇O2 Kinetics After Priming Exercises of Different Duration but Same Fatigue
Participants
n=10 healthy young adults (25 ± 3 y)
Protocol
Three step transitions from a 20-W baseline to a power output below the gas-exchange threshold (MOD; unprimed = MOD_PRE)
Two priming bouts, each followed by the same MOD transition: 3 min at 90% of peak power output (P3MIN → MOD_3MIN) and 6 min at 80% of peak power output (P6MIN → MOD_6MIN)
Measured: VO2 time constant (τVO2) of MOD, the O2 supply-to-demand ([HHb]/VO2) ratio, and neuromuscular fatigue (isometric MVC, high-frequency doublet) before and after each priming bout
Key Results
The two priming bouts produced similar fatigue: MVC fell -29 ± 6% (3-min) vs -34 ± 7% (6-min), high-frequency doublet amplitude -48 ± 13% vs -43 ± 11% — not significantly different
τVO2 of moderate exercise was ~25% smaller (faster kinetics) after either priming bout than unprimed, with no difference between the 3-min and 6-min bouts
The [HHb]/VO2 ratio was higher unprimed (1.13 ± 0.12) than after 3-min (1.02 ± 0.04) or 6-min priming (1.02 ± 0.04) — better matching of O2 delivery to demand after priming
Conclusion: a shorter, higher-intensity priming bout accelerated VO2 kinetics as much as the longer, lower-intensity bout when the muscle fatigue induced was similar
Mechanism
The lower [HHb]/VO2 ratio after priming indicates improved O2 delivery relative to utilisation at the onset of the next bout. Inference, not tested: the priming effect appears tied to the degree of muscle perturbation/fatigue rather than to bout duration, so a short hard bout and a longer moderate-hard bout that produce the same fatigue prime equally.
Practical Application
In 10 healthy young adults, 3 min at 90% of peak power primed subsequent moderate exercise as well as 6 min at 80% (τVO2 ~25% faster in both cases) — when the two bouts caused similar neuromuscular fatigue (MVC -29% vs -34%); a shorter, harder priming effort is as effective as a longer one
The study did not include a low-fatigue priming bout, so it does not show that "2 min is enough" or that shorter priming is less fatiguing — both bouts here dropped MVC by about a third
Choose the priming format by what fits the warm-up: a short hard effort saves time without losing the kinetics benefit; the subsequent exercise tested was moderate intensity, not a race effort
Not from this paper; the base's own practice: warm-up template 5-10 min easy → one ~2-3 min effort above threshold → ~5 min easy → session/event
Limitations
Priming tested before moderate-intensity (below gas-exchange threshold) exercise, not before a severe-intensity or performance bout
Healthy young adults, not identified as trained cyclists; sex not stated in the abstract
Both priming bouts induced substantial fatigue (~30% MVC loss); a lower-fatigue dose was not tested
No DOI line in the entry (the PubMed record carries one; not added here)
How this entry was checked and changed
Why this level
regraded 2026-09-27 from B+: crossover, n=10 (<15)
Content correction 2026-09-27
"n=14 trained male cyclists" -> n=10 healthy young adults (25 ± 3 y); Journal MSSE 50(1) -> Journal of Sports Sciences (PubMed 28721747).
"2, 4, 6 min of heavy priming, all vs no priming, then severe exercise" -> abstract: 3 min at 90% PPO vs 6 min at 80% PPO, each followed by moderate exercise; τVO2 ~25% smaller after both.
"Fatigue lower after shorter priming" -> abstract: fatigue was matched (MVC -29 vs -34%, not different); "2-min priming = same benefit, less fatigue" and the "105-110% FTP" template removed / relabelled as base practice.
Level B+ -> B (crossover, n=10); Tier 2-3 -> 1-2.