Interoceptive sensitivity and physical effort: Implications for the self-control of physical load in everyday life BEATE M. HERBERT, a PAMELA ULBRICH, b and RAINER SCHANDRY a a Department of Psychology, Ludwig-Maximilians-University of Munich, Germany b Human Science Center, Ludwig-Maximilians-University of Munich, Germany Abstract This study examined the relationship between interoceptive sensitivity and the behavioral self-regulation of physical load. According to their performance in a heartbeat detection task, 34 participants were classified as good or poor heartbeat perceivers. Participants pedaled on a bicycle ergometer for 15 min and were free to choose the tempo of their cycling. Good heartbeat perceivers covered a significantly shorter distance and showed a significantly smaller increase in mean heart rate, stroke volume, and cardiac output. There were significant negative correlations between heartbeat perception score and covered distance, changes in heart rate, changes in stroke volume, and changes in cardiac output. These results were not explained by differences in physical fitness level (PWC 150 ). The findings suggest that good heartbeat perceivers show a more finely tuned behavioral self-regulation of physical load than poor heartbeat perceivers. Descriptors: Interoceptive sensitivity, Heartbeat perception, Behavioral self-regulation, Physical effort, Somatic markers The self-perception of cardiovascular activity may play an im- portant role in the self-regulation of physical activities in healthy persons as well as in patients with coronary artery disease (e.g., Kollenbaum, 1990; Kollenbaum, Dahme, & Kirchner, 1996; Kollenbaum, Dahme, Kirchner, Katenkamp, & Wagner, 1994; Pennebaker, 1981). Kollenbaum and coworkers (Kollenbaum, 1990; Kollenbaum et al., 1994, 1996) demonstrated that healthy subjects tend to underestimate their heart rate across all intensity levels of physical workload. In patients with coronary artery disease, a pronounced tendency toward underestimating physical load, especially at the upper limits of tolerable physical stress, was observed. Thus, these patients may exceed the upper limit of medically justifiable workload and in doing so place themselves at risk for physical, cardiac complications (Kollenbaum, 1990). In the context of a ‘‘competition of cues’’ model for the per- ception of physical symptoms, the first experiment in a series of studies by Pennebaker and Lightner (1980) demonstrated that when jogging at a constant pace on a treadmill, healthy individ- uals reported increased feelings of fatigue when listening to their own breathing as compared to street sounds or no acoustic stimulation. This finding suggests that an undisturbed encoding of internal cues results in increased self-perception of fatigue and further physical symptoms. In a second study by Pennebaker and Lightner, participants were free to run at their own pace on two different kinds of courses of equal distance (one cross-country and interesting, one a track course and boring). The authors hypothesized that participants might actually adapt their jogging pace in accordance with their perceptions of fatigue. Given that undisturbed encoding of internal cues had earlier been shown to determine perceptions of fatigue, jogging on the more interesting cross-country course (where the perception of internal bodily cues is diminished) should result in greater physical output (i.e., faster running pace) before subjects reach their fatigue limit. Subjects would thus be expected to jog at a faster pace on the cross-country course and perceptions of fatigue should be com- parable over the two courses. The results of the study demon- strated that participants jogged at a slower pace with significantly longer jogging times in the track-course condition, in which the uninteresting and non-attention-demanding external environ- ment caused individuals to be more aware of their bodily pro- cesses. Measures of fatigue, however, remained the same. Pennebaker and Lightner suggested that the self-perception of bodily processes such as breathing and other internal bodily symptoms may control the degree of physical effort a person is willing to exert, that is, the self-control of physical load. The aforementioned research failed to take into account that pronounced interindividual differences exist in degrees of symp- tom perception (‘‘interoceptive sensitivity’’; e.g., Critchley, Wiens, Rothstein, O ¨ hman, & Dolan, 2004; Katkin, 1985; Pollatos & Schandry, 2004; Schandry, 1981; Wiens, Mezzacappa, & Katkin, 2000). On the basis of the studies described above, it would seem likely that those individuals with more precise access to information about physical changes (related to physical load) We thank Prof. Dr. Ursula Hess and two anonymous reviewers for their helpful suggestions and comments on our manuscript. Address reprint requests to: Beate M. Herbert, Department of Psychology, Biological Psychology, Ludwig-Maximilians-University of Munich, Leopoldstr. 13, 80802 Munich, Germany. E-mail: beate. herbert@gmx.de. Psychophysiology, 44 (2007), 194–202. Blackwell Publishing Inc. Printed in the USA. Copyright r 2007 Society for Psychophysiological Research DOI: 10.1111/j.1469-8986.2007.00493.x 194