When starving a car of fuel, it runs slowly or poorly. As it is fed more fuel, it accelerates to the limit that it can burn gasoline. Your body works the same with glucose. A major problem today for many informed athletes is that the outrageous claims and nutritional hype has turned them off to supplementation. It has at least made them disbelieving the claims of many manufacturers of those types of product make.
Performance drinks work and they work well.
But they will never be claimed by us to be some nonsensical steroid replacement, with unbelievable claims of overnight growth. Glucose and glucose polymers fed before and during exercise, significantly delay the onset of fatigue and increase performance. Hundreds of experiments and published independent studies too numerous to is the only real secret to spectacular results. That intensity can be enhanced by delaying fatigue through the maintenance of high blood glucose. This is achieved most easily through the correct use of a quality training drink.