science lesson

Read an article in the Metro newspaper yesterday about sports drinks. The piece by Jo Steele reads:

"Want to be a better athlete? Well, forget altitude training and high-carb diets - it's your taste buds you should be concentrating on.

"Swilling a sugary sports drink around the mouth before exercising can apparently boost performance - even if it is spat out afterwards.

"Sugars - carbohydrates - in liquids such as energy drinks fire receptors in the mouth which stimulate the brain to increase output, tests found.

"The result is an average two per cent boost in exercise performance, with the added bonus of athletes not even feeling as if they are working any harder.

" 'Much of the benefit from carbohydrate in sports drinks is provided by signalling directly from mouth to brain rather than providing energy for the working muscles,' said physiologist Dr Edward Chambers.

"Energy drinks have long been known to boost exercise performance but experts have said the sugar hit alone is not enough to explain the improvement ...

"[During endurance tests with cyclists] previously unidentified receptors in the mouth sent pleasure signals to the brain, which reduced the cyclists' perception of the workload, said Dr Chambers, of Birmingham University, in the Journal of Physiology.

Interesting stuff there. So, sports drinks have two roles: to provide a bit of energy for the working muscles and to provide a placebo effect for the brain. This actually makes a bit of sense - Noakes writes about fatigue in terms of a Central Governor in his book Lore Of Running. He writes on page 19 (fourth edition)

"... the increasing feeling of fatigue and the progressive reduction in the capacity of the exercising muscles to maintain a constant work output during prolonged exercise results from currently unrecognized processes in the brain, which presumably act to prevent bodily harm during such exercise. This model theorizes that performance during exercise is determined by two separate phenomena:

1. A pacing strategy that is preprogrammed into the athlete's subconscious brain as a result of previous training and racing experiences.
2. Acute alterations to that preprogrammed strategy resulting from sensory input from a variety of organs - heart, muscle, brain, blood and lungs, among others - to the exercise controller or governor in the brain. Output from the controller to the motor cortex then determines the mass of skeletal muscle that can be activated and for how long, thereby determining the pacing strategy that the subconscious brain adopts during exercise.

"At the same time, information is sent from the controller to the emotional and other centers in the brain. These influence the level of discomfort that is felt, the emotional response, and the self-talk and self-doubt that are additional but poorly understood features of the fatigue that develops during exercise.
Hope you were paying attention at the back ...

Also updated this page with a couple of things kindly provided by John Pares. And also this page.