Modulation of startle and heart rate responses by fear of physical activity in patients with heart failure and in healthy adults

Fear of physical activity (FoPA) is prevalent in patients with heart failure and associated with lower physical
activity despite medical exercise prescriptions. The present study examined physiological indicators of FoPA by
assessing startle modulation and heart rate responses after affective priming with lexical stimuli of positive, neutral,
and negative valence, as well as words related to physical activity as potentially phobic cues. After screening
for FoPA in patients with heart failure and healthy adults, twenty participants each were assigned to one of three
subsamples: a healthy control group and two cardiac patient groups scoring either low or high on FoPA. The
high-FoPA group showed more pronounced startle potentiation and heart rate acceleration (i.e., mobilization of
defensive behavior) in the phobic prime condition compared to controls. Differences in FoPA accounted for 30%
of the startle potentiation by phobic priming, whereas general anxiety, depression, and disease severity were
no significant predictors in patients with heart failure. These findings suggest that heart failure-associated FoPA
elicits avoidance behavior at a largely automatic level, and might thereby contribute to low adherence to exercise
regimen. Thus, FoPA should be addressed in the design of psychological interventions for cardiac patients to
foster physical activity.