From The New York Times:
Can exercise influence how angry you become in certain situations? A study presented at the most recent annual conference of the American College of Sports Medicine provides some provocative if ambiguous answers. For the study, hundreds of undergraduates at the University of Georgia filled out questionnaires about their moods. From that group, researchers chose 16 young men with “high trait anger” or, in less technical terms, a very short fuse. They were, their questionnaires indicated, habitually touchy.
The researchers invited the men to a lab and had them fill out a survey about their moods at that moment. During the two days of the study, the men were each fitted with high-tech hairnets containing multiple sensors that could read electrical activity in the brain. Next, researchers flashed a series of slides across viewing screens set up in front of each young man. The slides, intended to induce anger, depicted upsetting events like Ku Klux Klan rallies and children under fire from soldiers, which were interspersed with more pleasant images. Electrical activity in the men’s brains indicated that they were growing angry during the display. For confirmation, they described to researchers how angry they felt, using a numerical scale from 0 to 9. On alternate days, after viewing the slides again (though always in a different order), the men either sat quietly or rode a stationary bike for 30 minutes at a moderate pace while their brain patterns and verbal estimations of anger were recorded. Afterward, the researchers examined how angry the volunteers became during each session. The results showed that when the volunteers hadn’t exercised, their second viewing of the slides aroused significantly more anger than the first. After exercise, conversely, the men’s anger reached a plateau. They still became upset during the slide show — exercise didn’t inure them to what they saw — but the exercise allowed them to end the session no angrier than they began it.