Attention weight lifters, iron pumpers and any others who are turned on by torturing themselves on Inquisition-like machines in health clubs designed to produce bulging biceps.

Here's a tip from researchers at the University of Utah: Use your head a little more, not just your muscles. And your heart.In tests on athletes, Dr. Paul Burgess found that if weight lifters think what they're lifting is too heavy to handle, it might as well be, because they'll have a hard time budging it.

The subjects were tricked repeatedly. Burgess and colleagues asked athletes to lift weights they believed they could move, even if the weights were heavier than they could lift. The jocks also were asked to lift weights they were told were cabled to the floor.

Measures of "force generation" were defined, Burgess said, and athletes who knew their weights were tethered down didn't try as hard.

But when lifting weights they ordinarily couldn't handle, they put forth more effort when told the weights weren't tethered down, Burgess said.

"When they knew there was a possibility the weight could be moved, they generated more force," he said. "If they know it's not impossible, they generate more force. If they knew in advance they could not lift the weight, they didn't put forth as much effort, though they claimed they did."

In a sense, he said, the study demonstrates the power of positive thinking. The "negative" thought that trying to lift a weight is futile induced the athletes to put forth less effort. So the study suggests, he added, that "looking at your favorite color, thinking positive thoughts, having fans cheering," all can have positive effects.

Athletes also were asked to repeatedly raise weights until they became so fatigued they could just barely raise them. Again, trickery was used, for the subjects couldn't tell when the researchers switched the weights to heavier ones.

The subjects were asked to estimate the heaviness of the weights as fatigue developed and to judge the effort required to lift them as they became more tired.

"We found as they got (more) tired, they thought what they were lifting was heavier," Burgess said. "They experienced an illusion. An object that was relatively easy to lift unfatigued felt two to four times heavier when the subject was so fatigued that he could just barely lift it. However, the effort required to lift the weight increased much more.

"We now have a basis for finding out what you have to do to maximize the amount of force you generate for a given amount of effort."

Maximizing effort should be a prime goal of coaches or any person in a position to motivate, he said.

"If you're in an environment where you feel there is a positive attitude toward you, where you're being supported in your efforts, you can do better," he said. "You can't do so well if you feel tied down."