Old Rule: Drink plenty of sports drink every run to boost performance.
New Rule: Do some “fasting workouts” to make muscles better fat burners.
Sports drinks aid running performance by limiting dehydration and supplying muscles with an extra source of energy. But you do not need a sports drink on every training run. Research has shown that sports drinks have no effect on performance in hard runs lasting less than one hour or easier runs lasting fewer than 90 minutes.
What’s more, other studies suggest the carbohydrates in sports drinks act as a physiological crutch by limiting some beneficial fitness adaptations that occur in response to training. Improvements in the muscles’ fat-burning capacity and other adaptations depend partly on the depletion of muscle glycogen stores during workouts. Sports drinks attenuate glycogen depletion and thereby blunt the body’s adaptive response to the run. Sports drinks are imperative for longer and harder workouts, but relying too heavily on them in training may make you less fit.
Take-Away Tip: Use a sports drink during roughly half of your runs lasting between one and two hours and during all of your runs lasting longer than two hours.