Fig. 1. HR, SBP, and DBP reactivity for the CFS and healthy, sedentary control groups when performing cognitive tests before, immediately after, and 24 hours after incremental treadmill exercise to exhaustion (mean ± SEM). Reactivity scores were calculated by subtracting the cardiovascular value during baseline from the value obtained during the cognitive test period. a = Significantly different when compared with control (p < .05); b = significantly different from pre-exercise values (p < .05).