Hypotheses: 1), Exercise performance will improve, at a level similar to those demonstrated for caffeine ingestion 2) ratings of perceived exertion will go down with the effect of causing intensity to go up 3) During sustained aerobic activity approaching the aerobic threshold alterations in substrate use will be minimal (but possibly meaningful in regard to performance); alterations at rest will be more pronounced. 4) acute alterations (6o min post single dose) in blood pressure, HRV, arterial stiffness and RMR will mirror the effects observed for more prolonged exposure in phase 1.