REF-185 · Gastin, 2001 · Sports Medicine, Vol. · Paper

Energy system interaction and relative contribution during maximal exercise

B+moderate evidenceMeasured on a mixed groupWritten before October 2026, being re-checked

Key Findings

Gastin reviews the interaction and relative contribution of the three energy systems — anaerobic alactic (ATP and phosphocreatine splitting), anaerobic lactic (glycolysis to lactate) and aerobic (combustion of carbohydrate and fat with oxygen) — during single bouts of maximal exercise, with emphasis on the aerobic system's role at high intensity.

The anaerobic pathways regenerate ATP fast but release limited energy per bout; the aerobic system has enormous capacity but delivers energy more slowly.

The classic 1960s-70s depictions rested on anaerobic-energy calculations that now look questionable and bred two misconceptions: that the systems respond almost sequentially, and that the aerobic system responds slowly and matters little over short durations.

More recent research: energy comes from every pathway during almost all activities, and the duration of maximal exercise at which anaerobic and aerobic contributions are equal falls between 1 and 2 minutes, most probably around 75 seconds — considerably earlier than traditionally suggested.

Key Finding: Aerobic-anaerobic crossover (equal contribution) at 1-2 minutes of maximal exercise, most probably ~75 seconds.

Interaction (as stated in the abstract)

All three systems contribute during almost all exercise, not one after another.
The aerobic system responds fast enough to matter even in short maximal efforts.
Equal aerobic/anaerobic split: 1-2 min, most probably ~75 s. Beyond that, the aerobic share dominates.
Per-duration percentage splits (e.g. how much is aerobic at 10 s or 30 s) are tabulated in the full text of the review but are not in the abstract and are not reproduced here.

Practical Application

During a single maximal effort all three energy systems work at once, and the aerobic system already supplies half the energy after only 1-2 minutes — most probably around 75 seconds — far earlier than the old sequential model taught (narrative review, Gastin 2001).
Inference, not tested: any effort longer than a couple of minutes — a 3-min VO2max interval, a 5-min climb, a 20-min threshold block — is predominantly aerobic; "anaerobic capacity" is a limiter mainly for efforts of about a minute and under, and even there the aerobic system is contributing.
Inference, not tested: short sprints and attacks lean on the alactic and lactic pathways, so their specific training is repeated-sprint work (REF-191, REF-184), while the capacity to repeat them across a long race is bought by the aerobic system.
Not from this paper; the base's own practice: for multi-hour events the base prioritises the aerobic engine (VO2max, threshold) and treats late-race sprint capacity as something protected by pacing and fuelling rather than trained in isolation. The review describes single maximal bouts, not multi-hour racing.

Limitations

From the design as the abstract reports it: a narrative review, not a systematic review or meta-analysis — no search method or pooled data are described.
Scope is single bouts of maximal exercise; repeated efforts and prolonged submaximal exercise are outside it.
The equal-contribution point is a range (between 1 to 2 minutes, "most probably around 75 seconds"), and the review itself notes that the early depictions rested on calculations of anaerobic energy release that now appear questionable.
How this entry was checked and changed
Why this level

regraded 2026-09-27 from A: authoritative narrative review, no systematic method or pooled data

Content correction 2026-09-27
Percentage-by-duration ladder (0-10 s 80/20%, 10-45 s 60/40%, 75 s+ >80% aerobic) deleted: not in the abstract; the abstract gives only the ~75 s / 1-2 min crossover.
"NOT 120+ seconds as previously assumed" -> abstract: "considerably earlier than has traditionally been suggested" (no figure); reworded.
Mountain-cycling application (4.5 h, 90%+ aerobic, 20-min blocks) removed as a finding and replaced by labelled inference and base practice; Sport "cycling, sprint" -> general; Level A -> B+.
Cross-references to duplicate stubs repointed to their canonical entries (REF-162->REF-306); the stubs were emptied on 2026-09-27.
Cross-reference labels pointed at the wrong entry or named the wrong author (checked against each cited entry's byline); repointed to the entry the label describes, or removed where the base holds no such paper.
2026-09-28: added Limitations from the abstract (Europe PMC, DOI 10.2165/00007256-200131100-00003, PMID 11547894).