There are countless times I have watched sports on TV and commentators provide their insights on the regulation of fuel use. “And then you switch to fat metabolism” is one of the commonly heard catch phrases. Last weekend this happened again when I was watching cycling. But it is a myth that we have a switch that allows us to select different fuels. How does it work? Please pass this one on to TV commentators.Energy for muscle contractionWhen we exercise the muscle contracts and we need e...