Posted: August 22, 2006

Science of Sport: What is the best way to fuel for a 2 hour race?

Shawn Dolan, PhD, RD

The two primary concerns for an event lasting 2 hours include replacing fluid and electrolytes and consuming carbohydrate. However, a 2 hour race can be a unique challenge for many athletes. A 2 hour race for one person might be winning an Olympic distance triathlon while for another it might be completing a ˝ marathon and still another athlete might be competing in a mountain bike race. Most athletes who participate in these events attempt to maintain a relatively high intensity for a relatively long period of time (considering the intensity). This can lead to fatigue towards the end of the event. So the burning question is “how can I prevent that fatigue while still performing my best”?

It is clear that an adequate supply of carbohydrate in the working muscle (glycogen) and bloodstream (blood glucose) are essential to an athlete’s ability to sustain an intense effort over time. Therefore, performance can be limited by the amount of carbohydrate that is stored in the working muscles. As the temperature increases (as is the case in many races during the summer), the larger concern for performance is hydration status and the body’s ability to cool itself. Exercise capacity can be improved when outside sources of carbohydrate and fluid are provided; this seems to be especially true during the last portion of the race when fatigue tends to set in and body temperature increases. Does this mean you can wait until the last 30 minutes of the race to refuel or drink? Probably not! To prevent fatigue, it is more beneficial to drink fluid that contains carbohydrate and electrolytes early in the race and continue drinking regularly throughout (every 15-30 minutes), rather than waiting until the later stages of the race when it may be too late. Electrolytes like sodium and potassium are important nutrients to replace during. Those athletes, who are salty sweaters, should consider a sport drink that is specifically designed for endurance events that provide a greater amount of electrolytes. This is particularly important in hot and/or humid climates even for those athletes who are not salty sweaters!

General fueling guidelines include consuming 30-60g of carbohydrate per hour when the event lasts longer than 1 hour, or approximately 1g per kg body weight per hour. Guidelines for amounts of fluid and electrolyte to be consumed during a race can only be very general because of the large variation in individual sweating rates and composition of sweat. Optimal fluid replacement should include frequent drinking of small amounts (if possible). Most commercial carbohydrate-electrolyte sport drinks provide 14-18 g of carbohydrate per 8 oz. If you choose to consume carbohydrate in this form, drink approximately 16-32 oz per hour during a two hour race. This recommendation is for an ideal situation. Athletes must consider other factors such as the type of activity, the opportunities to consume carbohydrate/fluid during the event, the impact of consumption on gastrointestinal discomfort, and certainly the stress surrounding a race before they can determine the appropriate amount of fluid and fuel. Consuming carbohydrates and electrolytes at the recommended levels should be done during training. This will allow your body to recognize these nutrients and accept them during a race. Not practicing your fueling during training can and in most circumstances will greatly reduce how well you absorb nutrients on race day.

Tips
• Know before you plan – research the event and find out what sports products (i.e. sport drinks, gels, water) will be available and at what point during the race. And begin using these in your training.
• Develop a race day nutrition plan that you practice during training – just as you would develop a training plan, consider what and how much you will have to drink and/or eat during training and racing.
• Always keep in mind that recommendations are simply guidelines – consuming carbohydrate and fluids during exercise can improve performance but not for all individuals in all situations.
• What you choose to consume should depend on the nature of the event (running, triathlon, cycling, mountain biking), the climate, your pre-event nutritional status, and your individual characteristics (i.e. body size, physiology).
• Remember that optimal fueling begins long before the race begins – daily training meals and snacks are just as important for race preparation as your training plan.
• Try options other than sport drinks for fueling during a race – combine water with sport gels (with or without caffeine), Clif Bloks, sport bars, Jelly Belly Sport Beans, etc.

The Endurance Research Board's (ERB) objective is to offer a broad perspective on both innovative and long-standing endurance nutrition. In addition to having advance science degrees, each member of our ERB races at an elite level. Our scientists are professional mountain bikers, professional triathletes and Cat 1 cyclists. Members of the Endurance Research Board include: Sally Warner MA Ph.D., Neal Henderson MS CSCS, Shawn Dolan Ph.D., Bob Seebohar, MS, RD, CSCS

* The ERB is a resource of First Endurance Nutrition

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