05 June 2012

Exercise affects risky decision-making

A new study suggests people may be less risk-averse shortly after they exercise – although researchers said they still don't know what could explain the effect.


A new study suggests people may be less risk averse shortly after they exercise – although researchers said they still don't know what psychological or physiological changes could explain the effect.

One clue could be differences in gender. A secondary analysis of the data showed that exercise influenced men's decisions, but not women's.

"If you look at the economics world, the more risk you take, the better your gains are," said Dr Scott Collier, the senior author on the research from Appalachian State University in Boone, North Carolina. In his team's study, he added, "Men took more chances after exercising; women didn't change at all."

How the study was done

Dr Collier and his student, Kaylee Davis, presented the findings at the American College of Sports Medicine's annual meeting in San Francisco.

Their study involved 18 people (mean age, 42) who took a 40-question survey measuring risk seeking and risk aversion for monetary gains and losses on three different days. The survey included questions such as choosing between receiving R854 today or R8 547 in one month, as well as lottery-type decisions.

Directly before the survey on the second day, the participants ran on a treadmill for 30 minutes at 65% of their oxygen consumption (VO2) peak.

On the baseline and third measurements, the researchers found that people tended to be risk averse when it came to monetary gains.

However on the second day, directly after exercising, participants were more likely to make riskier choices over monetary gains (p<0.05) than on days one or three.

Link stronger in men than women

In data not presented at the conference, that link was strong for men – but non-existent for women.

Dr Collier said that after exercising, men's risk score dropped from 23 to 11.5, then returned to baseline at 14.89 (max=40, higher score indicates more risk averse). Women's scores, on the other hand, barely changed – dropping from 19.75 to 18.65 after exercise.

Davis and Dr Collier said the next step is to determine why exercise affects risk-taking, specifically in men.

Possibilities include serotonin and dopamine released by exercise, or the amount of blood flow going to the brain, according to Davis. It's possible, Dr Collier added, that the release of certain neurotransmitters during exercise might be greater in men than women – explaining their different responses.

Men more risk-seeking

"It is well-established that men tend to be more risk-seeking than women," said Dr Craig Fox, who studies behavioural decision theory at the University of California, Los Angeles Anderson School of Management.

"There has also been some work linking testosterone to risk-seeking behaviour," he added.

Thus, one question is whether exercise increases testosterone levels for men but not women, who could be tested by taking saliva samples, Dr Fox, who wasn't involved in the new study, told Reuters Health in an email.

Dr Collier said his team is thinking next of looking into functional magnetic resonance imaging of the brain during decision making to compare men's and women's responses to risk-related questions.

(Genevra Pittman, Reuters Health, June 2012) 

Read more:

Benefits of exercise

Bias in decision making leads to depression




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