A new study suggests fans shouldn't feel entirely guilty for spending so much time watching their favorite teams.
Australian researchers found that when humans watch sports on television, their heart rate and breathing rate rise. For the first time, the researchers claimed, this study proves that "muscle sympathetic nerve activity" increases when people watch physical activity.
"Recording this nerve activity provides a very sensitive measure of the body's physiological responses to physical or mental stress," said one of the lead researchers, Vaughan Macefield. "We know that the sympathetic nervous system -- which supplies the heart, sweat glands and blood vessels, as well as other tissues -- increases its activity during actual exercise. Now we have shown that it increases when you are watching a moving scene as if you were running yourself."
In the study, researchers measured participants' physiological parameters as they watched a video of someone running. They compared those results to the measures they produced when the person on screen stopped jogging.
The team noticed that heart rate, respiration, skin blood flow and sweat release all increased while participants watched the jogger run.
"Although these changes were small, they were all appropriate physiological responses to exercise," said Rachael Brown, who conducted the study with Macefield. "This dovetails with our recent work on the emotions, where we found that viewing emotionally charged images, such as erotica, increases our sympathetic nerve activity and sweat release."
Brown and Macefield cautioned that while watching sports may increase sympathetic nerve activity, it is not a proper substitute for exercising.