Are Exercise Effects on Valence-Modulation of the Acoustic Startle Eyeblink Response Trait Dependent?: 2537 June 1 2 45 PM - 3 00 PM

Studies using objective probes for emotional state conclude no effect of exercise on affective processing. However, these studies fail to control for trait differences in sensitivity to affective cues and have been primarily restricted to prescribed (rather than self-selected) exercise intensities. It is possible that effects of exercise on affective processing of appetitive and aversive stimuli are moderated by motivational dispositions (approach/avoidance) reflective of individual differences in functioning of neural systems responsible for behavioral inhibition and behavioral activation (BIS/BAS traits). It is also possible that effects are influenced by perceived control of the exercise intensity. PURPOSE: This laboratory experiment tested the hypotheses that 1) changes in sensitivity to emotional stimuli would manifest for those stimuli to which one is naturally predisposed to attend (i.e., aversive stimuli for BIS-dominant, and appetitive stimuli for BAS-dominant individuals), and 2) effects would be enhanced following exercise at a self-adjusted intensity. METHODS: We examined valence-modulation of the acoustic startle eyeblink response during affective picture viewing before and after moderate intensity exercise with and without the opportunity to adjust intensity, or quiet rest among 58 undergraduates scoring high or low for BIS/BAS traits. RESULTS: A 4 way mixed-model ANOVA indicated a main effect for valence [F(2, 108) = 16.21, p < .01, η2 = .23, ε = .97], consistent with expected effects of picture content. There were no effects of personality group (p ≥ .18, η2 ≤ .08). Helmert contrasts revealed a 3-way quadratic interaction between valence, condition and time [F(1, 54) = 6.2, p =.02, η2=.10]. Follow-up RM-ANOVAs revealed a quadratic valence X time interaction during the prescribed exercise condition [F(1, 57)=7.38, p=.01, η2 = .12]; the reduction in ASER magnitude in response to neutral stimuli was greater than that in response to unpleasant or pleasant stimuli. These effects were not observed in the adjustable exercise or control conditions. CONCLUSIONS: Results confirm that cycling exercise does not alter emotional response to affective pictures, regardless of motivational disposition, and extend the evidence to conditions in which participants can alter the exercise intensity.