Looking at the color red before engaging in a physical activity may boost your performance, a new study finds. Children and college kids who read words written in red before a physical task seemed to have an edge in performance speed and intensity, compared to those who saw other colors.

The color red sends a primal message to the brain, which may be why sirens, stop signs, and warning signals are often red. It’s also the color of blood and of flushed opponents, says coauthor Andrew Elliot: "Red enhances our physical reactions because it is seen as a danger cue. Humans flush when they are angry or preparing for attack. People are acutely aware of such reddening in others and its implications."

College students squeezed a handgrip as forcefully as they could when they read the word "squeeze," written in black against a red, gray, or blue background. When the word was placed against a red background, the participants squeezed with more force.

To test the idea that the color red may improve physical performance, the researchers had 30 children (4th through 10th grade) pinch a metal clip. The kids read their participant number, which was either written in red or grey, before beginning. Kids whose number was written in red squeezed the clip much more forcefully than those whose number was in grey.

In a follow-up experiment, college students squeezed a handgrip as forcefully as they could when they read the word "squeeze," written in black against a red, gray, or blue background. When the word was placed against a red background, the participants squeezed with more force. Additionally, the speed with which they reached their maximum force was faster. There was no difference between blue and gray backgrounds in speed or force.

Colors were all matched in hue, brightness, and intensity, which is important, and somewhat rare in color studies. "Many color psychology studies in the past have failed to account for these independent variables, so the results have been ambiguous," says Elliot. Controlling for these variables assures that the effect on force and speed is actually due to the color itself, rather than any of the other aspects that make up a color.

The authors conclude that red likely acts as a threat cue for humans, as it does for other primates, although it also has different implications in other situations (like romantic ones). Since the tasks at hand here were "static" ones, looking at how red affects more "active" actions will need to be addressed. It’s unclear what implications the research has for sports psychology — the researchers speculate that it may affect sports requiring short bursts of energy (like weightlifting) rather than longer events like marathon running. If you’re so inclined, it might be fun to play around with the color to see what, if any, effects it may have on you — or your opponent.

Elliot is a researcher at the University of Rochester; the study was published in the April 2011 issue of Emotion.