Carbohydrate and fluid on the bike: two separate calculations
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Start with the session
A short, easy ride does not automatically require a sports drink. Duration, intensity, previous meals and opportunities to stop change the question. AIS separates carbohydrate intake from fluid needs: a bottle can contribute to both, but the two goals do not always match. [1]
AIS reference ranges, not a personal dose
| Activity | AIS practical reference |
|---|---|
| Brief, under 45 minutes | Carbohydrate during exercise generally unnecessary |
| Sustained high intensity, 45–75 minutes | Small amounts, including oral exposure |
| Endurance, 1–2.5 hours | 30–60 g carbohydrate per hour |
| Very long, over 2.5–3 hours | Up to 90 g/hour; multiple transportable carbohydrates |
These are practical guidance ranges, not an instruction to reach the maximum. The source’s duration bands are not a continuous formula: they do not automatically produce an exact dose at 50 minutes or 2 hours 45. Higher intakes need tolerance and practice, not a first trial on event day. [1]
Worked example: a 6% bottle
A drink containing 6 g per 100 mL provides 30 g in 500 mL and 45 g in 750 mL. Consuming 500 mL plus a gel labelled as 25 g in one hour gives 55 g carbohydrate. These are illustrative sums, not instructions to drink 500 mL/hour or use that gel. Check the actual serving on the label, not just the scoop count.
Citing expert positions, AIS gives 4–8 g/100 mL as the composition for fast delivery and tolerance; typical products are around 6–8%, and some range from 2 to 14%. It is not the definition of every product. Mixing a powder with less water changes concentration. Adding gels changes total intake even if the bottle is unchanged. [1]
Do not drink more just to reach the carbohydrate target
If carbohydrate needs are high but fluid needs lower, the sources can be separated rather than forcing extra drink. Conversely, a carbohydrate-free drink does not meet a fuel target. The hyponatraemia consensus identifies drinking beyond losses as the main mechanism: prevention targets drinking behaviour. Sports drinks contain less sodium than serum: the consensus states they will not prevent hyponatraemia in athletes who overdrink, because the dilutional effect overwhelms the sodium. Thirst is a reference for preventing excess, not a reason to ignore heat, symptoms or water access. [1][2]
Test the plan and record the outcome
- Count all carbohydrate from bottles, gels and foods without counting servings twice.
- Practise the products, concentration and intake method intended for the event.
- Record duration, conditions, actual intake and tolerance, not only the original plan.
Nausea or discomfort does not automatically mean more salt or a different powder is needed. AIS discusses variables including concentration, amount and individual tolerance. A useful plan is repeatable and manageable, not simply the one with the largest number. [1]
Sources and limits
- Australian Institute of Sport, Sports drinks. Practical guidance: activity ranges, composition and tolerance.
- Third International Exercise-Associated Hyponatraemia Consensus, 2015. Consensus on preventing fluid excess, not a personal recipe.
Sources checked on 29 October 2026.