Nutrition during open-water swim

Nutrition during a 10–20 km open-water swim

Main fuel: carbohydrates

A practical target for many trained swimmers is 60–90 g of carbohydrate per hour, especially for swims lasting several hours. Some highly trained athletes can tolerate more, but this should be practiced in training.

Good options:

Carbohydrate sports drink — easy to take from a feeding bottle

• Banana — small pieces if tolerated

  Honey or maple syrup diluted in water

  Energy gel — with water

  Chews/jelly sweets — easy to portion

  Small boiled potatoes — useful for longer swims if the swimmer tolerates solid food

  Carbohydrate + electrolyte drink

Example feeding strategy

For a swimmer expected to swim 4–5 hours:

TimeFeeding0:30Carbohydrate drink1:00Gel + water1:30Carbohydrate/electrolyte drink2:00Gel or liquid carbohydrate2:30Carbohydrate drink3:00Gel + water3:30Carbohydrate/electrolyte drink4:00Gel or preferred carbohydrate4:30+Continue according to pace and conditions

Don't wait until the swimmer feels hungry or tired. Start feeding early and continue regularly.

Hydration

The swimmer also needs fluids and electrolytes, but overdrinking can be dangerous.

A good approach is to determine the swimmer's individual sweat/fluid losses during training and build the feeding plan around that. In very long swims, sodium becomes particularly important, especially in hot conditions.

The most important coaching rule

Never introduce new food or supplements on race day.

Every gel, drink, feeding bottle and solid food should be tested repeatedly during long training swims

.Protein during a long open-water swim

For swims lasting 4+ hours, a small amount of protein can sometimes be useful, particularly when the athlete is doing very long endurance sessions. However, carbohydrate should remain the primary fuel during the swim.

A practical approach:

• Before the swim: normal meal containing carbohydrate + 20–30 g protein

• During the swim: primarily carbohydrate and fluids; if the swimmer tolerates it, include a small amount of protein in a drink, particularly during very long swims.

• After the swim: 20–40 g high-quality protein + carbohydrate to support recovery.