Sports drinks, gels, bars, Fig Newtons, bananas, peanut butter and jelly sandwiches and even pizza have all been used as sources of nutrition for half and full Ironman races.  In fact, the items I listed above are just the ones I’ve heard about or witnessed being consumed—who knows how long the real list goes!

First of all, your muscles burn fat as they are taxed.  However, your muscles need carbohydrate to burn this fat.  Muscles store carbohydrate as glycogen (long term stored energy).  This glycogen energy source is tapped out at about 2000 calories for a trained triathlete.  Why is this important?  Because, this fuel source is only good for about 2-2.5 hours of high stress performance.  So, for those of you with plans on racing at the sprint and Olympic distance triathlons or in ½ marathons or less, race day nutrition isn’t as critical for those competing in full marathons or ½ and full Iron distance competitions.  In summary, those of you competing for 2.5 hours or less may now ignore the rest of the article!  For those of you going longer, read on…

Now that you are aware of how much energy your body can store (approximately 2000 calories), we need to identify how many calories are being burnt and how to replace those calories to perform between 3-17 hours.  Caloric burn rates can vary anywhere between 400-750 calories per hour, depending on the specific individual and effort being given.  The second part of our equation is identifying how many calories our bodies can process and turn into energy in that same time period.  This again can vary between 300-750 calories per hour.  Confirming this number is very personal and should be established during training rides and runs.  Success is starting at 300 calories per hour and monitoring your energy levels both during and post exercise.  Interesting tidbit here—most of us should be replenishing about 250-400 calories per hour, but Lance Armstrong actually consumed 1 gel for every mile he ran in the 2006 New York City Marathon!  Lance came in just under 3 hours and consumed 2600 calories!  That puts his processing rate at a whopping 866 per hour!

OK, back to reality for the rest of us.  With so many options for fuel, our choices are extensive and can be very personal.  Regardless of your choice, you will need to check your product’s nutritional information and make sure you are totaling our 250-400 calorie target.  Most gels are about 100 calories per, many bars average about 250 per bar and liquid options (Infinit, Carbo-pro) have suggested servings of about 280-300 calories per 16 oz serving.  Additionally, 8 oz servings of Coke and/or Gatorade average about 40-50 calories.  Regardless of your choice, you will need to supplement your fuel intake with water to ensure successful digestion.  Even gel and beverage fuel manufacturers suggest 3-4 oz of water to complement their nutrition.  Once you’ve identified your fuel source and added up the necessary water to process this fuel, you will now need to make sure you take a measured approach in consumption.  A good rule of thumb is 100-150 calories every 15-20 minutes along with the 3-4 oz of water which will deliver your targeted calories and help you stay hydrated at 16-24 oz of fluid per hour.

Finally, here are a couple of ‘watch outs’ and thoughts around deviating from this program.  For those of you thinking that you can simply down all your calories at the beginning of each hour, think again.  If you flood your digestive tract with too many calories, you will force your heart to pump a disproportionate amount of blood to your stomach.  This takes vital blood away from the muscles you need to compete.  At the other end of the spectrum, training at a 90-95% max of your maximum heart rate will disallow proper digestion as your body will flow a disproportionate amount of blood to your muscles and away from your stomach.  This is the cause of so many ‘reversals’ (or vomiting) which cause so many longer distance athletes to lose vital nutrition and end in DNFs (did not finish).  For those of you procrastinators out there, trying to catch up in your race by loading up on nutrition should you have missed previous occasions will meet with the same end as those trying to ‘forward buy’ their nutrition.

So, measured, methodical introduction of calories and measured, methodical use of those calories (60-80% of max heart rate) will ensure your fuel is processed and used as economically and efficiently as possible.