When you think of the word “energy” during workouts, you’re probably thinking of protein shakes and sports drinks—not your electricity bill. But if you exercise at home, you might not be thinking about just how much it can impact your energy usage.

So we decided to look up the energy use of a few popular home exercise options. From streaming workout videos on Netflix to treadmill marathon training, here’s how they ranked.

1^st Place: Going Outdoors
Okay, sure, this one’s pretty self-explanatory, but it still bears repeating. The most energy efficient way to get in shape is to get outdoors. Whether that means taking a walk around the neighborhood, hiking a trail, or jogging laps at your local high school’s track, you can’t use much electricity if you can’t plug in.

2^nd Place: Exercise Bikes
No matter how inclined you are to exercise outdoors, this is still the Midwest, and there’s still going to be Mother Nature to reckon with. Between the polar vortexes and triple-digit temperatures, some days you just ain’t goin’ outside.

Exercise bikes can still provide a highly efficient way to get in shape. In most cases, these bikes create resistance through magnetic brakes, which means they don’t actually need much electricity to operate. Most of the juice actually goes to power the LED display that tells you how fast you’re going and how many calories you’ve burned.

And even though it’s not common yet, some of these bikes have even been outfitted so they can generate electricity—and that’s just cool enough for us to rank exercise bikes in second place.

3^rd Place: Aerobics Videos
Whether you watch ‘em on VHS or stream them through Netflix, aerobics videos are like bringing an exercise class into the comfort of your own living room. And sure, you’ll use some electricity to run your electronic devices, but no more than you’d use watching old Mr. Ed reruns, and with considerably better results for your health.

4^th Place: Elliptical Machines and Stair-Steppers
These can be a pretty mixed bag. Some would rank right up there with exercise bikes, in that they’re almost completely self-powered. But other models require electricity to create resistance, and that’s where you start to lose efficiency. Self-powered machines also tend to cost more, making it less likely that the average consumer will be able to purchase one. These combined factors led us to place these options a little lower on the list.

5^th Place: Treadmills
Whoa, Mama. Treadmills land last place on this list by a long shot. That’s because they rely entirely on electric powered motors to operate. An average model uses 600 to 700 watts, which is a little like leaving four large LCD televisions on for the duration of your workout. That might not sound like much, but if you use the treadmill regularly over the course of a month, you’ll notice it for sure when you get that energy bill.

Want more tips on how you can save money on your energy bill? Contact your Energy Advisor today.