Physical exercise may help people exert more control over impulsivity, a recent small study suggests.
“There’s a particular type of task called ‘delay discounting’ that presents individuals with a series of choices between ‘smaller/sooner’ and ‘larger/later’ rewards. It’s something we all experience in our lives. Do you want a little money now—or wait and get a lot of money later? The degree to which one chooses that smaller/sooner reward is called impulsivity, and that has been linked to obesity problems, gambling, and most forms of substance abuse.”
says Michael Sofis, a doctoral student in applied behavioral science at the University of Kansas, who led the study.
According to Sofis, a change in one’s ability to value future events might keep maladaptive behavior in check and increase the likelihood of making healthy choices. He designed a pilot study, and a subsequent larger study, to see if exercise could trigger changes in delay discounting.
Decision Making Effects
Sofis and coauthors Ale Carrillo and David Jarmolowicz recruited participants and instructed them to walk, jog, or run laps on a track at “individualized high and low effort levels” and recorded participants’ own perceived effort.
“There’s a lot of neuroscientific evidence that suggests mood-altering effects of physical activity could change how you make decisions,” says Sofis. “There are a variety of proposed biological and neurological mechanisms and different effects for people with different genetic profiles linked to mental health issues. Studies say if I have a genetic profile linked to higher rates of depression and anxiety, I’m more likely to get benefits from physical activity.
We wanted to create an individualized, but still standardized approach,” Sofis adds. “We had people rate their perceived effort on a scale of six to 20. Six would be just sitting on a couch — and 20 would be maximal exertion. We’d start them at levels of eight and 10, respectively. The idea is that we’d slowly shape them up to higher effort levels. For each person, the amount that they’re exerting is going to relate to amount they’re going to enjoy it.”
Participants’ perceived exertion was established before the study to establish a baseline measure, treatment was tracked for seven to eight weeks, and participants were also asked to self-report maintenance of increased exercise for an additional month. Delay discounting was tested before, during, and after treatment, and during maintenance using a standardized 27-item delay discounting task called the Monetary Choice Questionnaire.
Delay Discounting Improvement
he researchers found statistically significant improvements in delay discounting were evident not only during the treatment phase of increased exertion but also that improvements were maintained a month afterward for the group.
“Our study is the first, to our knowledge, that shows maintained changes in delay discounting at follow-up,” Sofis says. “In our study, 13 of 16 participants kept their improved self-control.”
Sofis says the research helps strengthen emerging evidence that delay discounting can be altered. Due to links between discounting and many clinical issues, Sofis suggests that researchers and clinicians alike should attend to discounting as a treatment target.
“This is becoming important as a clinical treatment target,” he says. “If you could measure one outcome and potentially see a change, you should be able to see myriad other changes at once.”
For people showing problems with impulsivity or self-control, Sofis says the takeaway message is simple: Exercise could help.
Michael J. Sofis, Ale Carrillo, David P. Jarmolowicz
Maintained Physical Activity Induced Changes in Delay Discounting
Behavior Modification Vol 41, Issue 4, pp. 499 – 528
Image: Bill McConkey. Wellcome Images