"Music can make people happy no matter what their day has been like," he says. "It entertains and educates."
Rachel Goldberg, co-owner and instructor at Washington cycle studio Ride D.C., says her music choices go beyond BPM, style and genre. She uses the phrasing of the music to get the most out of her rides.
"When you marry your body's movements with the music it's a more holistic experience," she says. "You start flowing with the music." If there is a chorus or other recurring crescendos in the music, Goldberg might use those to increase the intensity.
"The music becomes your North Star - it guides you."
It also distracts you - something many of us have relied on during a long treadmill workout. Cedric Bryant, chief science officer for the American Council on Exercise, says this is the aspect of music that resonates the most with him. "I enjoy using music as a distraction," he says, adding that music can keep you going no matter how tired you are.
Distraction, whether it be music or even a comedy show, can be helpful in a workout - at least in the beginning, Foster says.
That's where the importance of the beat and arousal come in. "After about 20 minutes or so, 'Larry the Cable Guy' is not enough to keep us going," says Foster, who used comedy in one of his studies. "We need more than a joke to carry us."