ABSTRACT
Physical activity of any type in everyone, patients and athletes alike, leads to adaptation at all levels of the body. This chapter reviews what happens at each of these steps if exercise of sufficient duration, intensity, and frequency is undertaken. Aerobic capacity (VO2 max), anaerobic threshold (AT), adaptation of fuel utilization, muscle cell and capillary alterations, and genetic influences are described. The chapter focuses, though, on how CPET can provide essential information on the state of conditioning or deconditioning that an individual is experiencing and how training will affect the measured variables. In that light, the chapter concentrates on VO2, AT, ventilatory response, and sustainable work, which are most easily applied to daily activities, work, recreation, and athletic performance. Various types of training are also discussed. Deconditioning and over-training syndrome will be reviewed so that the clinician can be prepared to recognize these conditions as well.
