REF-116 · Graham, 2001 · Sports Medicine, Vol. · Paper

Caffeine and Exercise: Metabolism, Endurance and Performance

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

Graham's 2001 review covers what was known about caffeine and exercise. Caffeine is ergogenic at intakes well below the IOC's then-acceptable limit. It does not raise maximal oxygen capacity directly but can let an athlete train at a higher power output and/or longer, and increases speed and/or power in simulated race conditions across efforts from about 60 seconds to 2 hours.

For strength, the limited data suggested no effect on maximal ability but better endurance/resistance to fatigue. There is no evidence that pre-exercise caffeine causes dehydration or ion imbalance. Coffee appears ineffective compared with pure caffeine.

Pharmacokinetics are similar in men and women and unaffected by exercise or dehydration; users and non-users appear to respond similarly and withdrawal may not matter.

On mechanism, the review is explicit that the popular "spares glycogen by boosting fat oxidation" theory has very little support and is at best incomplete; caffeine may act partly by creating a more favourable intracellular ionic environment in active muscle, facilitating force production per motor unit.

Key Findings

Ergogenic across efforts lasting from about 60 s to 2 h; raises speed and/or power in simulated races.
No direct increase in maximal oxygen capacity; allows higher power or longer training.
Strength: no effect on maximal ability; enhanced endurance / resistance to fatigue (limited data).
No dehydration or ion imbalance from pre-exercise caffeine.
Coffee less effective than pure caffeine; theophylline is also ergogenic; possible synergy with ephedrine and anti-inflammatory agents.
Pharmacokinetics: same in men and women; unaffected by exercise or dehydration; users and non-users respond similarly.
Mechanism: fat-oxidation/glycogen-sparing theory has very little support; a more favourable intracellular ionic environment in muscle is a candidate mechanism. Central (adenosine-receptor) actions are discussed in the full text (full text; not checked against the abstract).

Practical Application

Caffeine improves speed and/or power in simulated race conditions for efforts from about 60 seconds to 2 hours without raising VO2max, without dehydrating the athlete, and — contrary to the old story — not by sparing glycogen through extra fat oxidation, a theory the review finds has very little support.
Take it as pure caffeine (tablet, gum, gel) rather than relying on coffee, which the review found comparatively ineffective; men and women, habitual users and non-users, respond similarly.
For strength work expect better resistance to fatigue, not a higher maximum.
Not from this paper: doses — the position-stand range 3-6 mg/kg is REF-115; the low-dose (< 3 mg/kg, ~200 mg) case is REF-114.

Limitations

2001 narrative review; the mechanism is described by the author as unknown; strength data were limited at the time.
How this entry was checked and changed
Why this level

regraded 2026-09-27 from A: narrative review without systematic method, from a leading caffeine research group (Graham); no pooled data

Content correction 2026-09-27
"Perceived exertion reduction 5-10%" and "efficacy threshold 200 mg (≥ 3 mg/kg)" -> not in the paper; deleted. Dose guidance pointed to REF-115 / REF-114.
Entry stated the mechanism as established CNS adenosine antagonism -> the abstract says the mechanism is unknown, rejects the fat-oxidation theory and proposes an intracellular ionic mechanism; adenosine kept only as a full-text point, labelled.
Added the abstract's findings: 60 s to 2 h window, no VO2max change, no dehydration, coffee < pure caffeine, strength endurance but not max, pharmacokinetics. Level A -> B+ (narrative review).