Miller, PC, Hall, EE, Chmelo, EA, Morrison, JM, DeWitt, RE, and Kostura, CM. The influence of muscle action on heart rate, RPE, and affective responses after upper-body resistance exercise. J Strength Cond Res 23(2): 366-372, 2009-Ratings of perceived exertion (RPE) are routinely used to monitor, assess, and prescribe aerobic exercise. Heart rate (HR) is another measure used to evaluate exercise intensity. Additionally, affective responses to aerobic exercise have been studied and seem to be influenced by the intensity of the exercise. The perceptual, HR, and affective responses to resistance exercise have not been effectively established. The purpose of this study was to examine whether differences in affect, RPE, and HR exist among college-aged women (n = 31) performing three different modes of resistance training: concentric (CE), eccentric (EE), and traditional concentric/eccentric (TE) performed at varying resistances. The women were asked to complete four sessions of resistance training on variable resistance machines: chest press, seated row, overhead press, and biceps curl. The first session was used to establish the 10-repetition maximum (RM) load for each station. Subsequent sessions involved the execution of training in one of the three test conditions: CE, EE, or TE. The participants performed three sets of each lift at 80% 10-RM, 100% 10-RM, and 120% 10-RM. The data revealed lower RPE during EE than the other test conditions. Similarly, EE elicited more mild HR response than either CE or TE. This finding is potentially important for the establishment of training programs, especially for those individuals recovering from an illness, who had been previously sedentary, and who are involved in rehabilitation of an injury.