How To Fuel Your Body For Intense Exercise

Before Training:

  • 2-3 Hours beforehand eat a medium sized portion of Complex Carbohydrates for gradual release of energy.  Common examples are: Wholegrain bread, whoelgrain rice, Wholewheat Pasta, Porridge, Beans or Lentils.
  • 15-20 Mins beforehand eat a small amount of simple sugars to give you a good kick-start.  For example: Fruit, half a bar of chocolate, a few Sweets, a couple of  biscuits etc
  • If doing an event it’s always advisable, to carb load with complex carbs the night before too.

During Training:

In my experience when doing regular training for an hour or less, water is all that’s required.  For training sessions, races or events that are very intense or last over an hour, to ensure you get the maximum benefits and efficiency from your body when training.  I recommend consuming a small amount of simple sugars and electrolytes within every 45 minutes.  Obviously it is also important to rehydrate.

Having cycled for 42 days 4362km across Australia, I learned over and over again, that the optimum time to refuel the body during prolonged exercise is 45minutes.  If left for an hour or more my energy and electrolyte levels and therefore speed and concentration, dipped too low.  It takes time to digest and absorb the sugar and/or electrolytes, pre-empt the dip by eating/drinking before this happens.

Exhausted Cycist

Certain types of food can cause acid reflux or diarrhea, so be careful in what you chose to eat and never try new foods, drinks or gels for the first time during an intense training session or race.  Everyone is different, but personally half a bar of chocolate every 45mins works best for me.  Gels don’t last more than 15mins and upset my stomach.  Other people use bananas or cereal bars but for me, chocolate is best.


Personally I sweat a lot, so to prevent cramping and big dips in energy levels mid race, I avoid caffeine beforehand so as not get dehydrated and only use it when I need it – in the last half of a race.  But if training for 90mins or less, will have 100mg or more of caffeine.

After Training:

  • Straight after training eat a small amount of Simple Sugars to aid recovery and promote muscle repair.  Restoring energy quickly and effectively.  You should also immediately start rehydrating to ensure water levels and electrolytes are returned to normal.
  • Within 2 Hours eat a medium sized portion of Complex Carbohydrates and a medium sized portion of Protein (Meat, Dairy, Fish, Eggs, Tofu etc…), all to maximise muscle repair and growth.  For vegetarians, please remember to combine your foods, to ensure all 8 essential amino acids required for muscle repair are present.
  • Aim to get 8 hours of good quality sleep that night, again to maximise muscle repair and growth.

How to Identify Sugar/Energy & Electrolyte Deficiencies

During prolonged cardiovascular exercise your body uses up large amounts of your energy and electrolyte reserves.  If not managed correctly, this can lead to some potentially dangerous problems and significantly reduce your performance.

Sugar/Energy Deficiencies

This is usually quite easy to identify.  You feel sudden drops in your energy levels where your speed, strength, power or lap times drop noticeably.  If this happens, refuelling immediately with simple sugars will help, but it can take up to 10 minutes to return to peak performance levels.  Fuelling your body with simple sugars every 45 minutes during prolonged exercise should help prevent this.

Electrolyte Deficiencies

These deficiencies tend to occur gradually, are much harder to identify and can due to their very nature, be confused with energy deficiencies.  When electrolyte levels significantly drop, brain functions slow down, causing confusion and you can make snap incorrect decisions.  Your reaction times drop, your balance, coordination and proprioception worsen.  Your muscles begin to cramp or strain, you may experience nausea or stomach cramps, your body temperature will rise, causing you to overheat and in worst case scenarios collapse/faint. Depending on how low your electrolytes drop, you may experience some or all of these symptoms in varying levels of severity.

Examples of this could be:  having difficulty working out how long is left in a race, long distance runners tripping up, Tri-athletes/Cross country runners make simple mistakes and take wrong turns on courses or lose track of laps, Cyclists lose concentration and don’t spot gravel or touch wheels on straights, or when using gym equipment such as the spin bikes, you find it hard to work out your gear and speed.

A great way I discovered in Australia to help identify this, was every 45 minutes, to do a quick, simple maths equations or multiplication tables in your head, that you would normally find easy to do.  If this becomes difficult, then you may have low electrolyte levels.

Once again ensuring you hydrate and replenish your electrolyte levels every 45 minutes should help prevent this.  If it is too late, you might not recover your peak performance or may experience big peaks and troughs.

My top tip for staying hydrated is to drink warm or room temperature water.  It stops you going to the toilet as much and makes a huge difference.

author: Andy Kenny