A physiological monitoring system for noninvasively monitoring physiological parameters of a subject, comprising a fitness monitoring system for monitoring physiological parameters of a subject engaged in a physical activity, in accordance with one embodiment of the invention, includes (i) a monitoring garment adapted to cover at least a portion of a subject's torso, (ii) a magnetometer subsystem including a first magnetometer and a second magnetometer, wherein the first and second magnetometers are responsive to changes in distance therebetween, wherein the magnetometer subsystem is configured to generate and transmit a signal representative of a change in the distance between the first and second magnetometers, wherein the first and second magnetometers are incorporated into the monitoring garment, and wherein the first and second magnetometers are proximate to the subject's chest region when the monitoring garment is worn by the subject.