In a way, it can feel a bit silly to compare outdoor cycling to indoor spin classes. Both involve riding a bike. Both are good exercise. And both are healthy. Both also activate the same large muscles in your lower body — namely your thighs, butt, and hips, says Jinger Gottschall, an associate professor of kinesiology at Penn State University who has published research on high-intensity stationary bike workouts. “However, depending on the type of indoor bike, the activation may be less with indoor riding,” she adds.
Why? So-called “flywheel” cycles — the type where the pedals keep spinning even if you try to stop — are built to utilize momentum and may give your leg muscles a small assist compared to pedaling on an outdoor bike. So it’s possible that outdoor cycling will demand a little extra lower-body power compared to indoor spin cycling.
This possibility is backed by a small 2014 study in the Journal of Strength and Conditioning Research. The study team recruited 12 recreational cyclists and measured each rider’s heart rate and power output during 25-mile outdoor and indoor rides. The study participants were told to give the same amount of effort during each ride. Afterward, they rated the rides as equally challenging.
Their data said otherwise. All riders expended more power while cycling outdoors compared to indoors. “Power output” is a measure of exercise intensity, and the average rider increased his power output by 30 percent while riding outside. (One rider expended 70 percent more power outdoors despite rating the indoor ride as equally challenging.) The study participants’ heart rates were also elevated a bit more during the outdoor ride.
Calm down, spinners. We know what you’re thinking, and you’re right: Equating a self-paced indoor ride to a sweat-soaked, music-fueled, instructor-led spin class is apples and oranges.