Race Fuel

Runners, cyclists, and other endurance athletes are constantly looking for ways to improve their performance.  One of these ways is to use nutritional supplements to “boost” their energy and allow them to perform longer or harder before fatigue sets in.  Carbohydrates are the primary source of energy during exercise.  They can be stored in the liver and skeletal muscle as glycogen.  When exercise lasts longer than 60 minutes, glycogen stores begin to deplete. Without our number one supplier of energy during exercise fatigue will be soon to follow.  An easy way to help maintain carbohydrate levels, slow down the rate of glycogen depletion and aid in performance is to consume a carbohydrate/electrolyte solution.  Ideally this beverage should be 4-8% carbohydrate solution and you should try to consume 8-12 oz consumed every 10-15 min (around 30-60 grams of carbohydrates total).  This should help maintain carbohydrate levels within the body and help delay the onset of fatigue.  The beverage or food should be high in carbohydrate and well tolerated which can significantly boost the carbohydrate delivery to working muscles.  These sources of carbohydrates can include: sports beverages, crackers, bananas, carbohydrate gels, or bread to help supplement the body with additional sources of carbohydrates during exercise.

Another important, and often overlooked, ergogenic aid during endurance events is water.  During exercise in the heat, sweat rates of up to 1.5-2 L/hr have been reported. This can quickly lead to dehydration and ultimately a drop in performance.   Every 1% loss of your body weight as sweat, results in an increased heart rate of 7 beats per minute which can put additional stress on the cardiovascular system during exercise.  Therefore the number one priority during long distance events (especially in the heat) should be hydration.

A number of studies have also shown that caffeine ingestion can significantly increase fat mobilization (up to 18%) in the blood and allow it to be burned as fuel.  This allows carbohydrate stores to last longer and essentially “spare glucose” which can also delay the onset of fatigue.  Studies have shown increases of up to 20% in performance following caffeine ingestion.  Doses of 3 to 9 mg per kg of bodyweight or a total of 250mg have shown to be effective.

In summary, make sure you are consuming enough fluids and carbohydrates during bouts of long exercise.  Also, the addition of caffeine may help with sparing glucose and allow you to last longer before fatigue kicks in.