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Rough day at work? You might not feel like exercising

Sept. 29, 2009
Courtesy McMaster University
and World Science staff

Have you ev­er sat down to work on a cross­word puz­zle only to find that af­ter­wards you haven’t the en­er­gy to ex­er­cise? Or have you come home from a rough day at the of­fice with no en­er­gy to go for a run?

A study pub­lished Sept. 29 in the re­search jour­nal Psy­chol­o­gy and Health re­ports that if you use your will­pow­er to do one task, it de­pletes you of the will­pow­er to do a to­tally dif­fer­ent task.

A study re­ports that if you use your will­pow­er to do one task, it de­pletes you of the will­pow­er to do a to­tally dif­fer­ent task, such as ex­er­cis­ing.

“Cog­ni­tive tasks, as well as emo­tion­al tasks such as reg­u­lat­ing your emo­tions, can de­plete your self-reg­u­la­tory ca­pacity to ex­er­cise,” said Kath­leen Mar­tin Gi­nis of Mc­Mas­ter Un­ivers­ity in On­tar­i­o, lead au­thor of the stu­dy. “You only have so much will­pow­er.”

Mar­tin Gi­nis and col­league Ste­ven Bray used a so-called Stroop test to de­plete the self-reg­u­la­tory ca­pacity of vol­un­teers in the stu­dy. A Stroop test con­sists of words as­so­ci­at­ed with colours but printed in a dif­fer­ent col­our. For ex­am­ple, “red” is printed in blue ink. Sub­jects were asked to say the colour on the screen, try­ing to re­sist the tempta­t­ion to blurt out the printed word in­stead of the colour it­self.

“After we used this cog­ni­tive task to de­plete par­ti­ci­pants’ self-reg­u­la­tory ca­pacity, they did­n’t ex­er­cise as hard as par­ti­ci­pants who had not per­formed the task,” Mar­tin Gi­nis said.

Still, she does­n’t see that as an ex­cuse to let peo­ple loaf on the so­fa.

“There are strate­gies to help peo­ple re­ju­ve­nate af­ter their self-regula­t­ion is de­pleted,” she said. “Lis­ten­ing to mu­sic can help; and we al­so found that if you make spe­cif­ic plans to ex­er­cise—in oth­er words, mak­ing a com­mit­ment to go for a walk at 7 p.m. ev­ery evening—then that had a high rate of suc­cess.”

She said that by con­stantly chal­leng­ing your­self to re­sist a piece of choc­o­late cake, or to force your­self to study an ex­tra half-hour each night, then you can ac­tu­ally in­crease your self-reg­u­la­tory ca­pacity.

“Willpower is like a mus­cle: it needs to be chal­lenged to build it­self,” she said.

* * *

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Have you ever sat down to work on a crossword puzzle only to find that afterwards you haven’t the energy to exercise? Or have you come home from a rough day at the office with no energy to go for a run? A study published Sept. 29 in the research journal Psychology and Health reports that if you use your willpower to do one task, it depletes you of the willpower to do a totally different 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 of McMaster University in Ontario, lead author of the study. “You only have so much willpower.” Martin Ginis and colleague Steven Bray used a so-called Stroop test to deplete the self-regulatory capacity of volunteers in the study. A Stroop test consists of words associated with colours but printed in a different colour. For example, “red” is printed in blue ink. Subjects were asked to say the colour on the screen, trying to resist the temptation to blurt out the printed word instead of the colour itself. “After we used this cognitive task to deplete participants’ self-regulatory capacity, they didn’t exercise as hard as participants who had not performed the task,” Martin Ginis said. Still, she doesn’t see that as an excuse to let people loaf on the sofa. “There are strategies to help people rejuvenate after their self-regulation is depleted,” she said. “Listening to music can help; and we also found that if you make specific plans to exercise—in other words, making a commitment to go for a walk at 7 p.m. every evening—then that had a high rate of success.” She said that by constantly challenging yourself to resist a piece of chocolate cake, or to force yourself to study an extra half-hour each night, then you can actually increase your self-regulatory capacity. “Willpower is like a muscle: it needs to be challenged to build itself,” she said.