AI quick summary
- Caffeine at 3–6 mg/kg taken 30–60 minutes before riding improves time-trial power by 2–5%; the mechanism is adenosine receptor antagonism, not energy per se.
- Nitrate (beetroot juice, 6–13 mmol nitrate) taken 2–3 hours before exercise lowers the oxygen cost of submaximal effort by roughly 1–3%.
- Beta-alanine (4–6 g/day for 8+ weeks) raises muscle carnosine and helps efforts of 60–240 seconds; creatine (3–5 g/day) helps repeated sprint performance.
- BCAAs, HMB, and glutamine have no meaningful evidence for endurance cycling performance — skip them despite the marketing.
/ 01
The evidence hierarchy — AIS Group A
The Australian Institute of Sport sorts supplements into groups. Group A has strong evidence of benefit, low risk, and is permitted under WADA — the list every serious cyclist should start from. Group B has emerging evidence and is worth experimenting with. Group C has no good evidence of benefit (or evidence of no benefit) and is where marketing money lives. Group D is banned.
For endurance cycling, Group A collapses to four compounds: caffeine, nitrate, beta-alanine, and creatine. Everything else either has no effect, helps a different sport, or is still under study. This section covers the four that work, then lists the supplements that don't.
/ 02
Caffeine — the most evidence, most misused
Caffeine improves cycling performance by 2–5% in time trials and time-to-exhaustion tests. The mechanism is central: caffeine blocks adenosine receptors, which reduces the perception of effort and increases motor unit recruitment. It is not, despite popular framing, 'energy' — a pre-ride espresso does not add calories to the system. Secondary effects include increased fatty acid mobilisation, but the dominant effect is neural.
The dose is 3–6 mg per kilogram of body weight, taken 30–60 minutes before the target effort. A 70 kg rider targets 200–400 mg — roughly two strong espressos or one caffeine gel. More is not better: doses over 6 mg/kg increase side effects (anxiety, GI upset, hand tremor) without further performance gain. Caffeine is also a diuretic only in non-habituated users; regular coffee drinkers adapt and the fluid loss is negligible.
Caffeine content of common sources (aim for 3–6 mg/kg)
| Source | Caffeine (mg) | Equivalent for 70 kg rider (210 mg target) |
|---|---|---|
| Espresso (single 30 ml) | 60–80 | 3 shots |
| Brewed coffee (250 ml) | 90–120 | 2 cups |
| Energy gel (caffeinated) | 25–75 | 3–8 gels |
| Caffeine tablet | 100–200 | 1–2 tablets |
| Cola (330 ml) | 30–40 | 5–7 cans |
/ 03
Nitrate (beetroot) — the 1–3% edge
Dietary nitrate is converted in the mouth and gut to nitric oxide, which dilates blood vessels and improves mitochondrial efficiency. The measurable effect in cycling is a 1–3% reduction in the oxygen cost of submaximal work, translating to faster time trials and lower heart rate at fixed power. The effect is reliable in submaximal endurance efforts and weaker in pure sprint or very high-intensity work.
Dosing is 6–13 mmol of nitrate (roughly 400–800 mg), taken 2–3 hours before exercise. Concentrated beetroot juice shots are the standard source. Important caveats: antibacterial mouthwash destroys the oral bacteria that convert nitrate, eliminating the effect entirely; the response varies genetically, with about 20% of riders non-responders; and chronic daily dosing may be less effective than acute pre-event dosing.
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Beta-alanine and creatine — sprinter tools
Group A supplements for cycling — dose, timing, effect
| Supplement | Daily dose | Loading | Effect | Best cycling use |
|---|---|---|---|---|
| Caffeine | 3–6 mg/kg | None | 2–5% TT improvement | All-out efforts, 30 min–4 hr |
| Nitrate (beetroot) | 6–13 mmol | 3 days pre-event | 1–3% lower VO2 at fixed power | TT, climbs, breakaways |
| Beta-alanine | 4–6 g/day | 8 weeks to saturation | 1–2% in 1–4 min efforts | Sprint, kilo, points race |
| Creatine monohydrate | 3–5 g/day | 20 g/day × 5 days (optional) | 2–5% in repeated sprints | Track, sprinters, criteriums |
/ 05
The hype list — skip these
Branched-chain amino acids (BCAAs): cycling performance benefit is effectively zero when total protein intake is adequate. Leucine alone does the same job at lower cost inside a complete protein source. HMB: a leucine metabolite with modest evidence in untrained subjects and no meaningful benefit in trained cyclists. Glutamine: marketed for immune support and recovery, but controlled trials in athletes consistently show no performance effect. Collagen for joints: helps tendon and ligament health when paired with vitamin C, but does not improve cycling performance directly.
Testosterone boosters, 'mitochondrial' blends (PQQ, pyrroloquinoline), and most 'endurance' formulas fall into AIS Group C — no good evidence, well-marketed. Save the money. If a supplement worked as well as the label claims, WADA would be reviewing it and the AIS would list it in Group A.
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