Location: Healthy Body Weight ResearchTitle: Increasing discomfort tolerance predicts incentive senitization of exercise reinforcement: Preliminary results from a randomized controlled intervention to increase the reinforcing value of exercise in overweight to obese adu Author
Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2016
Publication Date: 4/1/2017
Citation: Roemmich, J.N., Flack, K.D., Johnson, L., Ufholz, K.E. 2017. Increasing discomfort tolerance predicts incentive senitization of exercise reinforcement: Preliminary results from a randomized controlled intervention to increase the reinforcing value of exercise in overweight to obese adults [abstract]. Federation of American Societies for Experimental Biology Conference. 31/149.3.
Technical Abstract: Objective: The reinforcing (motivating) value of exercise/physical activity (RRVex) predicts usual exercise behavior and meeting of physical activity guidelines. Recent cross-sectional evidence suggests, for the first time, that greater tolerance for the discomfort experienced during exercise is associated with greater RRVex. But, it is not known whether discomfort tolerance or RRVex can be increased. The primary aim of this randomized controlled trial is to determine whether the reinforcing value of exercise relative to sedentary behavior (RRVex) is increased after repeated exposures to exercise (i.e., incentive sensitization). The primary hypothesis is engaging in 300 kcal bouts of exercise will increase RRVex more than 150 kcal bouts and a no exercise control. A secondary hypothesis is increases in discomfort tolerance will be positively associated with the increase in RRVex. Methods: Preliminary results are from 63 adults who participated in a 3-arm, randomized, controlled, community-based, 6-wk exercise intervention. For the exercise arm treatments, participants engage in either 300 kcal or 150 kcal bouts of exercise 3 days/wk. For the control arm, participants receive no active intervention, but attend the same number of assessment visits. Outcomes are tested at baseline, after 6 weeks of treatment, and 4 weeks after treatment (10 weeks). RRVex is assessed via an operant responding task that used independent progressive ratio schedules of reinforcement to earn time for exercise (e.g., treadmill, elliptical) or sedentary (e.g. TV, magazines) behavior. The RRVex is calculated as the number of sessions completed for access to exercise/(sessions completed for exercise + sedentary). Discomfort tolerance is measured via the Preference for and Tolerance of the Intensity of Exercise Questionnaire. Usual activity is measured via accelerometer. Differences in groups across time is tested using a mixed linear model with time as a within-subject factor, treatment group as a between-subjects factor and subject as a random effect. Results: At this preliminary analysis, there are no significant main or interaction effects for RRVex. The group x time interaction for discomfort tolerance is p = 0.08 with baseline to end of 6 weeks of exercise training changes of 10.1%, 6.3% and -7.8% for the 300 kcal, 150 kcal, and control groups, respectively. The baseline to 10 week change in usual minutes of moderate-to-vigorous physical activity is 31.0%, -5.6% and -17.8% for the 300 kcal, 150 kcal, and control groups, respectively Importantly, individual differences in the increase in discomfort tolerance during exercise is predicting increases in RRVex at 6 (r = 0.33, p < 0.01) and 10 (r = 0.26, p = 0.06) weeks. Conclusions: These data provide novel insights into an individual difference variable, tolerance for the discomfort experienced during exercise, that is changeable with repeated exercise exposures; and when increased may promote increases in RRVex. Future work will determine how to most effectively increase discomfort tolerance.