In the past two decades or so, the number of people entering marathons has risen dramatically. An explosion in the number and variety of pre-run and on-the-run fueling products aimed at marathon runners and other competitors has accompanied this increase in participants. With so many products available, ranging from sports drinks to gels to glucose tablets to energy bars, it's natural to wonder whether Gatorade, the first sports replacement drink on the market, is superior to gels, or vice versa.

Physiology

As exercise physiologist Pete Pfitzinger explains, unless you have systematically "carbo-loaded," any race or training run lasting more than 90 minutes will deplete your stores of glycogen. Glycogen is the body's storage form of glucose, the main source of fuel when you run. Therefore, you need to take in some form of rapidly digestible carbohydrate during the run, and start the refueling process before the 90-minute mark to give your body lead time. This is where Gatorade and gels enter the picture.

Gatorade: Pros and Cons

James Caldwell of Vanderbilt University investigated the various claims made on Gatorade's behalf by its manufacturer, chief among them that it can improve endurance performance if consumed during training or competition. After reviewing various studies, he determined these to be true. The 6 percent carbohydrate concentration is ideal for rapid absorption, and Gatorade quickly replaces both carbohydrates and electrolytes. The downside is that you are generally at the mercy of race directors in terms of where Gatorade is placed on the course because you cannot easily carry it with you, and some people have a difficult time drinking sugary beverages on the go.

Gels: Pros and Cons

Gels are a newer addition to the carbohydrate-replacement palette. They are popular among distance runners because they can carry numerous gel packets with them during training runs and races -- special "gel belts" are made for this purpose. The drawbacks include the need to drink water when using a gel, making the fueling process more complicated than drinking Gatorade. In addition, research by Louis M. Burke of the Australian Institute of Sport has yielded mixed results. Burke found that gel supplementation was useful for soccer players, but that runners may not benefit owing mainly to gastrointestinal discomfort induced by the gels.

Conclusions

Because research to date offers no consistent conclusions about the relative efficacy of Gatorade and carbohydrate gels one way or the other, which you choose to use in your training and racing is more a matter of personal preference than of scientific certainty. The one sure thing is that when running very long distances, you need one or the other to maximize your performance. Pfitzinger suggests aiming to take in 600 to 800 calories during a marathon race to avoid glycogen depletion, so whichever carbohydrate-replacement route you choose, plan accordingly.