Have you ever walked into the gym, had a look around and noticed how seemingly over-prepared some of the patrons are – sports drinks, snack and water, bars, fruit, powders, and more… Are you doing something wrong? Do they know something that you don’t?


Whether and how much you need to eat and drink during exercise is dependent on various factors, such as the duration, intensity and objectives of the session as well as body composition goals which need to be considered.

In general:

  • Sessions lasting less than an hour (up to 90 minutes for lower intensity exercise) should require nothing more than fluids if the session has been initiated with adequate fuelling/food.
  • Sessions exceeding 60-90 minutes require refueling with carbohydrates, this will help to maintain energy levels to keep you performing at your best for longer.


Even slight dehydration can impair your athletic performance, therefore fluid intake should be a major priority for anyone that takes their sport seriously. Fluid requirements during exercise will be dependent on sweat rates, it is also very important to make sure that you are properly hydrated when you start the exercise.

  • Small amounts of fluid are usually required during sessions of exercise lasting less than an hour and thirst can be used as an indicator.
  • For longer sessions planned fluid intake should be actioned to avoid dehydration. In order to better understand your sweat rates it is advisable to weigh yourself before and after exercise, 1kg weight-loss will equate to 1l fluid loss. Requirements will usually vary between 150ml-350ml every 15 to 20 minutes depending on temperature, humidity, intensity etc.
  • Please remember that you can also OVER-hydrate by drinking too much, and this can be as dangerous as dehydrating (UNDER-hydrating). A balanced approach is needed and this is something to practice during training so you get it right on race day.


During exercise lasting more than 60-90 minutes, carbohydrates become very important to prevent “hitting the wall” – when your body runs out of available glycogen (energy) to fuel performance. Taking in easily digested carbohydrates can prevent this phenomenon from occurring.

As a general guide we require 30-60 g of carbohydrates per hour, this can further increase to 90 g in events with high levels of effort lasting more than 3-4 hours. Nutrition should be initiated after about 45 minutes and spread out across the hour as well as the particular sport you participate in allows.

Sports drinks can be a great way to contribute to your carbohydrate requirements as they provide both fluid and carbohydrates with electrolytes to promote rehydration.

It is important to remember your goals: if you are trying to lose weight you clearly do not want to consume too many calories so you’d err on the low side (perhaps 20-30g per hour). On a big race-day you might err on the high side (60-90 g per hour) to maximise your performance once-off.

Practice your nutrition strategies during training because individual tolerance varies and what works for one person may be a disaster for another during a competition.

What does 15g of carbohydrates look like?

  • 1 small banana
  • ¾ Energy Bar (brands do vary here so check the labels)
  • ½ – 1 sports gel (read nutritional table for exact nutritionals of each product)
  • 220ml sports drink (7% carbohydrate concentration)
  • +- 25g jelly sweets

Good nutrition and hydration practices during exercise can do wonders for your performance and quite literally prevent you from “hitting the wall”. You can use the “30g per hour from the second hour” rule as a rough starting guide to carbohydrate intake. And you should drink something in the region of 500ml per hour, again only as a starting guide. Practice your hydration and nutrition during training sessions until you find what works best for you.