Spring Marathon Season: Using Bicarb Effectively

With the spring marathon season in full flow, getting your fueling right can make a meaningful difference to performance. While most advice focuses on carbohydrate intake and the days leading into race day, this article looks specifically at how to integrate BICARRB into your race plan, and how it fits alongside your wider nutrition strategy.

Timing the Dose

For most high-intensity efforts, sodium bicarbonate is typically taken around 2 hours before. For a marathon, however, it can work better slightly closer to the start. This way the elevated bicarbonate levels overlap more fully with the race itself.

We recommend taking BICARRB ~90 minutes before the start.

This helps align peak buffering capacity with the later stages of the race, when fatigue has built up.

Adjusting the Dose

For longer efforts like a marathon, consider using a slightly reduced dose. If you normally take 16g, a good option is to drop down to 12g.

This helps balance the performance benefits with gut comfort which is especially important when you’re also taking in carbohydrates and fluids during the race.

Fuel to the Start Line & During the Race

Bicarb isn’t a replacement for carbohydrate intake.

Make sure you’re properly fuelled before the race begins, with glycogen stores topped up, including some carbohydrate intake in the final hour before the start. For example, FLYCARB’s HICARB provides 50g of carbohydrates in an easy-to-consume drink mix.

We also suggest taking between 60 and 100grams / hr of carbohydrate during the race.

Caffeine Strategy

Caffeine acts quickly and is often most valuable in the second half of the race, where it can support focus and perceived effort.

For that reason, consider using a non-caffeinated BICARRB pre-race, then adding caffeine during the race (e.g. via a gel) to target the second half. This is our preferred strategy.

This allows you to:

• Time caffeine for when it matters most
• Avoid taking stimulants too early

As always, only do this if it’s something you’ve tested in training.

Putting It Together

• BICARRB Timing: ~90 minutes pre-race
• BICARRB Dose: Slightly reduced (4g less than you usual)
• Carbohydrates: Fully fuelled to the start + 60–100g per hour during
• Caffeine: Introduce during the race per training

Like any race-day strategy, you need to test this in training first, but when dialled in, it can be a valuable addition to your plan.

Separately, if you're looking for pacing advice that adjusts for the conditions, take a look at the calculator built by FLYCARB co-founder, Josh.