Caffeine blocks adenosine from binding to receptors in the brain. The first receptor site increases tiredness and the second receptor site suppresses euphoria and stimulation.
Catecholamine output is increased (noradrenaline and adrenaline) which results in free fatty acids being used for fuel, sparing muscle glycogen, and subsequently improving endurance.
Improves contractile force by enhancing calcium mobilisation in the sarcoplasmic reticulum.