Reaching down and touching your toes for a long hold doesn't seem like an intense workout because, well, it's not. You still burn calories while holding static stretches, but that's because your body's engine is always churning to keep you alive. The calories you burn are not comparable to more athletic endeavors, so don't count on stretching to get skinny. Flexibility exercise is still an important part of any fitness plan, however.
The calories you burn stretching really depend on how long and rigorously you go at it. A relatively active stretching session where you move postures every minute or so, such as in a Hatha yoga class, burns about 149 calories in 30 minutes for a 155-pound person. Because larger people have more mass to move around, they burn more calories than smaller people. A 120-pound person burns only 120 calories in that same amount of time, while a 200-pound person burns 178.
Stretching can mean more than just holding a muscle in an elongated position. Dynamic stretching is a technique often used prior to competition or high-intensity training sessions that involves using momentum, agility and speed to stretch the muscles and connective tissue. Examples of dynamic stretching include arm circles, body-weight lunges or high knee hugs. This type of stretching is akin to calisthenics, or body-weight exercises, and burns between 135 and 200 calories per half hour, depending on your weight.
If your stretching session consists of more sitting- and lying-on-the-floor sorts of moves, you'll burn fewer calories than a more active yoga-type session. You may burn a few more than the 42 calories burned by a 155-pound person in a half hour of sitting, but not a lot. Many of these calories are simply those you'd expend anyway to keep your blood pumping, organs filtering and breath flowing.
Things to Think About
Unless you are taking a yoga class, a stretching session usually lasts just five to 15 minutes. That leaves more than 23 hours during which you can burn calories. Just because stretching doesn't sizzle the 660 to 976 running a 9-minute mile does, doesn't mean its unimportant. The American College of Sports Medicine notes that any well-rounded exercise program includes regular flexibility training, whether that be static or dynamic in nature. Aim to stretch every major muscle group at least three times per week to preserve your optimal range of motion.