To improve evaluation of physical performance and stamina in athletes undergoing rigorous training, it is necessary to expand our current armoury of physical monitoring tools beyond say pulse rate and respiratory gas exchange. We also lack true biochemical measures of physical endurance at the trackside; the problem has been partly that tissue and blood access are not acceptable in a well subject and also that simplified assay is not available. This proposal utilises thin film fabrication tools create multilayer electrode strips able to respond to O2 and to lactate. The former will be based on O2 going through intact skin by an in situ heater augment O2 transport out from the skin surface, and the latter will respond to lactate in saliva by means of an enzyme to break down lactate to generate a detectable hydrogen peroxide. There is accumulating data that salivary lactate, though low, reflects blood values. The overall aim is to achieve non-invasive, reagentless devices for sports medicine use. Specifically, transcutaneous O2 will give a measure of peripheral tissue O2 delivery and lactate will give a measure of the level of the tissue oxygen deficit during extreme activity.