The invention pertains to the establishment, implementation and management of a personalized information system pertinent to a user's general health, wellness and/or sport performance. Disclosed is a system capable of transcutaneous measurement of a subject including at least one light source, at least one light detector, and at least one component for generating or storing at least one value of VC02 or at least one value of V02 from the detected signal. Further, disclosed is a portable device for analyzing the composition of the respired gasses of a subject including at least one air flow conduit through which the subject can inspire or expire air through the body of the device, at least one sampling portal, an oxygen sensor, and at least one flow sensor. A dual-battery system is also provided by which an uninterrupted power supply can be provided for electronic components.
