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Brain drain could affect your workout

September 25, 2009 |  6:06 pm

You've worked a pedal-to-the-medal day and now it's time to head to the gym. But as you hop on the treadmill and start to jog, your legs feel like lead.

You're probably not alone. According to a new study, energy put toward one task may deplete energy for more undertakings, like exercising.


Researchers at McMaster University in Canada studied 61 college students who were randomly assigned to two groups. Both performed 15-minute sessions on a stationary bike. In between, the intervention group was given a Stroop test in which they were given a word like "red" that was printed in blue, and asked to read the word. The control group was asked to read similar words that appeared in their actual color. All participants were also asked to plan a future workout, estimating at what intensity they'd work out.

All study subjects did worse in the second cycling bout than in the first. However, the intervention group showed a larger decrease in the intensity of their exercise. This group also planned a lower-intensity workout than did those in the control group.

But this isn't a pass to skip a workout if exercising after a tough day is the only option, says lead author Kathleen Martin Ginis, professor of health and exercise psychology in the department of kinesiology. Listening to music while exercising is one way to get energy flowing, as is making a concrete date to exercise. To that we'll add having a workout partner, which is great for accountability.

Willpower can even be strengthened, Ginis says, by things like challenging yourself to resisting a piece of cake. "Willpower is like a muscle," she said in a news release. "It needs to be challenged to build itself."

The study was published recently in the journal Psychology & Health.

-- Jeannine Stein

Photo credit: Sean Masterson