"When people run with music their rate of perceived exertion is lower than if they don't use music or other devices, " says Gershon Tenenbaum, director of the graduate program in sport and exercise psychology at Florida State University.

WSJ: Optimal Music for the Gym

In one study published in the journal Environmental Science and Technology last year, Dr. Micklewright and his team examined how the color of the imagery participants viewed while cycling would affect their mood and perceived feelings of exertion.

WSJ: Hard-Wired to Hate Exercise?