With all the bad press carbs have been getting lately (they can be easily stored as fat, and "higher-fat, lower-carb" diets are the cure-all for the insulin-insensitive), let me just say here and now that the demise of carbohydrates is premature at best. Carbohydrates are still the No. 1 fuel source for high-intensity exercise, and ingesting carbs during exercise can definitely help your workout!
Right now, there's little doubt that exercise lasting more than a couple of hours is limited primarily by carbohydrate depletion and dehydration. If you ingest a carb source during prolonged exercise, you'll delay fatigue and enhance performance. But what about high-intensity, intermittent exercise, such as sprinting, soccer, football or resistance training? Most of us don't lift weights for more than two hours, and our fatigue isn't entirely due to glycogen depletion or dehydration so can consuming a drink containing sugar help?
Investigators at the University of South Carolina, Columbia, tested the effects of carbohydrate feedings during intense intermittent cycling (sprint cycling) designed to induce fatigue within 40-60 minutes. In a double-blind protocol, physically active but untrained men and women ingested either a placebo or an 18%-carbohydrate solution (approximately 47 grams) immediately before exercise and a 6%-carbohydrate solution (approximately 16 grams) every 20 minutes during exercise. The volume of fluid ingested was 4 ml per 2.2 pounds (1 kg) of bodyweight; the exercise bout consisted of one minute of high-intensity cycling with a three-minute rest between bouts. Subjects performed this "sprint cycling" regimen until they could no longer maintain the same revolutions per minute.
For the carb group, plasma levels of glucose and insulin were higher 30 minutes after the commencement of exercise and until fatigue. The ratings of perceived exertion, which generally describes how hard the exercise feels to the subject, were less in the carb group. But more importantly, the average time to exhaustion was much longer in the carb group; in fact, they exercised approximately 50% longer (about 90 minutes vs. roughly 60 minutes) than the placebo group.
Thus, again, the benefits of ingesting carhs aren't limited to marathoners but are also quite important for us anaerobic guys and gals. If you looking for that extra edge or energy boost, it may be worthwhile to sip one of the various sports drinks available. Some guys like to dilute a non-carbonated soft drink in half; this probably works just as well as a sports drink. The only type sugar you might want to stay away from while you exercise is fructose or fruit sugar. For some people, fructose may cause stomach upset probably doesn't offer any advantages in performance arena either.