The purpose of this review is to examine the evidence that links specific physiological processes with central signals of perceived exertion during dynamic exercise. The physiological processes thought to be associated with a central signals of exertion include heart rate (HR), ventilation (VE), respiratory rate (RR), and oxygen uptake (VO2). Parallel changes in HR and ratings of perceived exertion (RPE) were not apparent when HR was manipulated experimentally. Heart rate does not appear to be associated with a strong central signal of exertion. Sensations of ventilatory function and discomfort are the only central signals that are consciously monitored. Corresponding changes in VE and RPE were noted when ventilatory drive was altered by hypnosis, induced erythrocythemia, hypoxia, or hyperoxia. Ventilation begins to provide potent sensory signals between 45-70% VO2max. Both the absolute and relative (percent VO2) oxygen uptake have been proposed as central signals. For a fixed VO2, RPE differed when comparisons were made between various experimental conditions. In contrast, RPE did not differ between conditions when expressed as a function of percent of VO2max. The relative VO2 is more likely to be associated with a strong sensory signal. Central signals involving VE and the relative VO2 are proposed to act as an amplifier that potentiates local signals in proportion to the aerobic metabolic demand.