NUTRITION ON RACE DAY/ COMPETITION DAY

Your body is well designed to supply fuel to your exercising muscles.  Fat is the preferred source of fuel for low to moderate intensity exercise.  Carbohydrate is the preferred source of fuel for moderate to high intensity exercise.  However, both fat and carbohydrate are used in any exercise session, it is the RATE at which it is used that will be different.

The main focus on race day/ competition day is to:

• Reduce the onset of fatigue by providing an adequate fuel supply
• Manage hydration

FUEL

Even the leanest athletes fat stores provides up to 50 000-100 000Cal of energy which can supports exercise for over 5 hours or low to moderate intensity.  Carbohydrate stores however, are limited and become depleted after 60-90 minutes of moderate-high intensity exercise.  In order to sustain moderate-high intensity exercise beyond 60-90 minutes, you need to consume carbohydrates while racing/ competing at a rate of 30-60g carbohydrate per hour.  Elite athletes competing in endurance events of exceptionally high intensities such as the Tour de France should aim to increase this further by consuming up to 90g carbohydrate per hour.

Another limiting factor of carbohydrates consumed during exercise is the rate at which they are digested, absorbed from the gastro-intestinal (GI) tract into the blood stream and then delivered to the muscle cells. Optimising the delivery rate of fuel to the muscles means:

• Consume simple carbohydrates such as glucose and fructose
• Start taking on carbohydrate within 30 minutes of the race/ competition.
• Sip water when eating foods to dilute stomach contents

AIM TO HAVE 30-60g CARBOHYDRATE PER HOUR

The following options provide ±25g carbohydrate.  Choose 1-2 of these each hour of exercise  (lasting longer than 60-90 minutes). Experiment during training sessions to know what works best for you.

FLUID DURING TRAINING SESSIONS

Guidelines on hydration are rather non-specific given that individual sweat rates, environmental temperatures and humidity can vary dramatically between runner and races.  The longer the training session, the greater the risk for developing dehydration, which can impair performance.  This is critical on race day but also a disadvantage to a good training session. 

The key is to drink enough fluid to match your sweat losses which is different for each individual athlete and the environmental conditions. 

Drinking to thirst is a good starting point; however this may not always be a strong enough indicator to avoid dehydration. 

A guideline is to drink approximately 250-500ml every 30 minutes, drink more if it is hot, humid or if your sweat rate is high.  Start drinking early on in the session and regularly in amounts that are comfortable.

Practice during training sessions and weigh yourself immediately before and after an exercise session. Ideally, weight loss should not exceed 2% of body weight.   

Measure fluid losses by weighing yourself immediately before and after a session and take into account the fluids you have consumed during the run.  1kg weight loss is the equivalent of 1L sweat losses.  Try to drink enough fluids to match your fluid losses.