Motivation to Exercise
Condition: Overweight; Obesity; Physical Activity
MeSH terms: Overweight
Study type: Interventional

Summary: 
      The purpose of this study is to understand how to make exercise more attractive to people.
    

Detailed description: 
      This investigation will address increased physical activity and will yield empirical evidence
      to inform developing tools to help individuals make healthy choices regarding physical
      activity (PA) and maintenance of healthy body weight. Behavioral Choice Theory provides a
      framework for understanding choices people make and how to shift an individual's choice
      toward healthier alternatives. The theory holds that choice is based on the relative
      motivating values of alternatives. One way to shift choice toward a healthier alternative is
      to increase the relative reinforcing value (RRV), or motivating value, of that alternative.
      Thus, increasing the RRV of PA behaviors could shift choice towards PA and away from less
      healthy, sedentary alternatives.

      Increasing the RRV of PA may allow PA to compete with more reinforcing, sedentary behaviors,
      resulting in a shift in behavioral choice. This process is termed "incentive sensitization",
      which was originally proposed to explain drug addiction. Incentive Sensitization theory
      posits that the RRV of a behavior is increased through repeated exposures, which produce
      neuroadaptations that increase craving of the behavior - after repeated exposures to a
      stimulus, a 'sensitization' or hypersensitivity to the incentive motivational effects of the
      stimulus follows. Another factor that influences motivation for a behavior is the development
      of tolerance to unpleasant aspects of that behavior. Opponent-Process Theory would account
      for the acquisition of motives where the initial reinforcer may be negative - the affect
      experienced after repeated exposures is opposite to that experienced during the first few
      presentations. For exercise, this would include tolerance to any discomfort, pain, fatigue
      and displeasure and a greater positive post-exercise affective response: the affect
      experienced during and after exercise has a greater motivational significance in PA
      participation than knowledge and beliefs regarding health benefits. Therefore, the
      investigators propose that repeated exposures to PA will produce tolerance to unpleasant
      aspects while increasing the post-exercise affect. Sensitizing PA reinforcement and
      increasing discomfort tolerance may be associated with increasing the duration and intensity
      of daily activity. There are likely to be individual differences in sensitization of PA
      reinforcement and development of discomfort tolerance. Single-nucleotide polymorphisms (SNPs)
      that alter dopamine tone in the central dopaminergic reward system and SNPs associated with
      altered pain perception may contribute to such individual differences. The investigators
      anticipate that a moderate PA dose (300 kilocalorie [kcal] expenditure) will produce greater
      incentive sensitization and tolerance than a low dose (150 kcal) and that SNPs related to
      central dopamine tone and pain perception may contribute to individual differences in
      incentive sensitization and changes in physical activity after repeated exposures to physical
      activity.
    

Intervention name(s): High Dose Exercise (300 kcal); Low Dose Exercise (150 kcal); No Exercise (0 kcal); Sedentary Option
Intervention type(s): Other; Other; Other; Other
Intervention description(s): Subjects will participate in 3 physical activity sessions per week expending 300 kcal per session and rate their liking of exercise.; Subjects will participate in 3 physical activity sessions per week expending 150 kcal per session and rate their liking of exercise.; Subjects will participate in 3 sessions per week expending 0 kcal per session and rate their liking of exercise.; Subjects will rate their liking of sedentary activities (reading magazines, playing word games, puzzles) as an alternative to exercise.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Other