That person reading a book on the treadmill may be on to something. A University of Florida study published last month in PLOS ONE showed that older people may be able to exercise more intensely—and gain the benefits associated with that—by doing two things at once.

The scientists examined 20 healthy people with an average age of 73, and 28 people with Parkinson's disease who were 7 years younger on average, per LiveScience.

The participants completed a dozen cognitive tasks while sitting in a room and while pedaling a stationary bike. They healthy participants sped up their pedaling an average of 25 percent (some hit 50 percent) when they were completing the simplest tasks, like saying "pa" as many times as they could in 10 seconds, or saying the word "go" when a blue star flashed on a projection screen.

(Never mind that the word "go" might prod one to do anything faster...) When the tasks became more difficult, the participants slowed—but in healthy adults, their speeds were, on average, never less than 2.6 percent faster than their baseline speed.

The researchers propose that cognitive tasks release the neurotransmitters dopamine and noradrenaline, which can make the brain's frontal lobes speedier and more efficient; in turn, motor and cognitive performance improve.

Those with Parkinson’s disease pedaled slower than the healthy adults (but still faster, on average, than their baseline speed while completing 9 of the tasks), which researchers believe is due to deficits in their neurotransmitters.

Researcher Lori Altmann was surprised by the findings: "Every dual-task study that I'm aware of shows when people are doing two things at once they get worse," she says in a press release.

(Could the "thunder god vine" end obesity?)

This article originally appeared on Newser: Study: To Exercise More Intensely, Use Your Brain

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