Healthy living * Mental wellbeing

Stress reduces willpower, stops you exercising

you only have so much willpower "Willpower muscle" needs exercise too

Tough day at work? Can't be bothered dragging yourself to the gym when you know a visit is long overdue? It's not entirely your fault, according to the results a new study.

The study, conducted at McMaster University in Canada, found that are reserves of willpower are finite, and if we use them to do one task it depletes our willpower to carry out a new task.

"Cognitive tasks, as well as emotional tasks such as regulating your emotions, can deplete your self-regulatory capacity to exercise," said Kathleen Martin Ginis, associate professor of kinesiology at McMaster University, who led the study.

To test the effect of mental tasks on a subjects commitment to exercise, the researchers recruited 61 student volunteers. Half of the students exercised on machines, and the other half given a Stroop test, designed to whittle down the students self-control.

A Stroop test consists of words for colours printed in a different colour. For instance, the word "red" would be printed in blue ink. Volunteers were asked to say the colour of the word shown to them on a screen without blurting out the printed word. (If this seems easy, try it yourself!)

After the Stroop test, the students were asked exercise for the second time. The results showed that students who had taken part in the Stroop test didn't exercise as hard as those who had not participated in the mental task.

"The more people "dogged it" after the cognitive task, the more likely they were to skip their exercise sessions over the next 8 weeks," Dr Martin Ginis said. "You only have so much willpower."

Unfortunately, a hard day at the office should not be used as an excuse to hit the sofa.

"There are strategies to help people rejuvenate after their self-regulation is depleted,” Dr Martin Ginis said.

Listening to music and planning in advance to exercise at a specific time are ways to get back on track. Constantly challenging yourself by, for instance, resisting a piece of chocolate cake, or by forcing yourself to study an extra half an hour, can increase you willpower capacity.

"Willpower is like a muscle: it needs to be challenged to build itself," Dr Martin Ginis said.

The study was published in the journal Psychology and Health.

This article was published on Mon 28 September 2009

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