Does clenching your muscles increase willpower?

Authors Iris W. Hung (National University of Singapore) and Aparna A. Labroo (University of Chicago) put study participants through a range of self-control dilemmas that involved accepting immediate pain for long-term gain. In one study, participants submerged their hands in an ice bucket to demonstrate pain resistance. In another, participants consumed a healthy but awful-tasting vinegar drink. In a third experiment, study participants decided whether to look at disturbing information about injured children devastated by an earthquake in Haiti and donate money to help. And in a final study, researchers observed actual food choices people made as they shopped for lunch at a local cafeteria.

"Participants who were instructed to tighten their muscles, regardless of which muscles they tightened -- hand, finger, calf, or biceps -- while trying to exert self-control demonstrated greater ability to withstand the pain, consume the unpleasant medicine, attend to the immediately disturbing but essential information, or overcome tempting foods," the authors write.

The authors found that the muscle tightening only helped when the choice aligned with the participants' goals (for example, to have a healthier lifestyle). They also found that the tightening of muscles only helped at the moment people faced the self-control dilemma. (If they did it beforehand, they felt depleted by the time it was time to make a choice.)

For example, in one study, health-conscious participants drank more of a health tonic (one part vinegar, 10 parts water) while they were tightening their muscles and drinking the healthy tonic. Those who were less health conscious were not affected by muscle tightening.

"The mind and the body are so closely tied together, merely clenching muscles can also activate willpower," the authors write. "Thus simply engaging in these bodily actions, which often result from an exertion of willpower, can serve as a non-conscious source to recruit willpower, facilitate self-control, and improve consumer wellbeing."