Giving your will power a work-out

Most of us have at some time experienced a lack of enthusiasm for exercise after a mentally tiring day at work. But now researchers at McMaster University in Ontario have suggested that will power, or “self-regulatory capacity”, used for one task can reduce that required for subsequent tasks.

Subjects were given cognitive tasks designed to deplete their self-regulatory capacity, then asked to exercise. Those who had carried out the task exercised less vigorously than those who had not.

This finding should not be used as an excuse for avoiding unwelcome activities or for giving in to temptation, because there are strategies to help rejuvenate will power after it is depleted. Listening to music can help, as can making specific plans in advance.

For example making a commitment in advance to go for a long walk at 7pm, even after a hard day at work, has a better chance of success. Scientists say that by challenging yourself to resist tempting foods, or to force yourself to exercise for longer, self-regulatory capacity can actually be increased.

Other research, carried out at the University of Kentucky, has led scientists to suggest that a person’s heart-rate variability — the capacity of the heart to be sensitive to changing demands — could be a way of estimating self-regulatory strength. They propose that the greater the heart rate variability, the greater the power of self-regulation.

Researchers asked students to fast for three hours, then presented them with a plate of carrots, chocolate chip cookies and chocolate. Some were allowed to eat only chocolates and cookies and others only carrots. Afterwards, they were asked to solve a series of anagrams.

Heart-rate variability increased more among students eating the carrots, suggesting they were giving their will power a work-out. This group also gave up sooner on the anagram puzzles, suggesting they had used up more of their self-regulatory strength during the food task.

Studies have also shown that physical exercise may help the self-regulatory “muscle”, say the researchers. This would have the benefit of both increasing heart fitness and working out the brain by forcing people to do something they do not necessarily want to keep doing.

As we turn back the clocks, and the long dark nights of winter stretch before us, the above advice may come in useful.