Abstract: Systems and methods for assessing cardiorespiratory fitness and for developing and implementing customized exercise regimens for developing cardiorespiratory conditioning. Initially, data is obtained from an individual to determine the individual's Anaerobic Threshold, Respiratory Compensation Point and VO2max. Preferably, the individual's Anaerobic Threshold is determined by gas exchange analysis which compares either ventilatory equivalent (VE/VO2) versus oxygen uptake or CO2 output versus oxygen uptake. Once the Anaerobic Threshold, Respiratory Compensation Point and VO2max have been determined, exercise regimens can be formulated that are comprised of zones or levels of training intensity expressed in terms of such physiological domains. Such zones or training intensities may be further designed to fall within a range of specified heart rates that coincide with an individual's Anaerobic Threshold, Respiratory Compensation Point and VO2max.