Does Yoga Count as Cardio?

By , SparkPeople Blogger
Yoga has seen a steady rise in popularity over the past few years.  According to a 2008 report released by Yoga Journal, 15.8 million American adults were practicing yoga.  In 2010, that number grew to 21.9 million.  The majority reported that they practice yoga for a number of health benefits, stress reduction and relaxation.  Yoga is a great complement to a well-rounded exercise routine, no matter what your fitness level.   It offers a variety of modifications (as needed), styles and intensities, giving it a wide appeal among exercisers of all fitness levels and goals.
But one of the questions I get most about yoga isn't whether I recommend it (I do), but whether it counts as a cardio workout. Could yoga replace one or more of your weekly treadmill or elliptical dates? 
Before you decide to give up your traditional cardio workout for the new power yoga class at the gym, you might want to get all of the facts first.      
The Definition of Cardio
The American College of Sports Medicine (ACSM) defines aerobic (cardio) exercise as "any activity that uses large muscle groups, can be maintained continuously, and is rhythmic in nature." It is also defined as exercise that increases the need for oxygen and elevates the heart rate to a specific level, typically at least 60-70% of one's max heart rate.  Traditional forms of cardio (think running, biking, swimming) use the largest muscle groups in the body in a rhythmic, continuous nature. This is what increases the heart rate to what is defined as an "aerobic" level and holds it there for several minutes at a time.
The Benefits of Cardio
Aerobic exercise strengthens your heart and lungs (which make up the cardiovascular system). During exercise, your muscles demand more oxygen-rich blood and give off more carbon dioxide and other waste products. As a result, your heart has to beat faster to keep up. When you follow a consistent aerobic exercise plan, your heart grows stronger so it can meet the muscles' demands without as much effort. Everyone, regardless of their weight, age, or gender, can benefit from aerobic exercise.

In addition, cardio burns more calories than any other type of exercise, making it the go-to type of exercise for weight loss. As we know, the more calories you burn, the more weight you'll be able to lose. So if weight-loss is a goal of yours, calorie burning is key.
Does Yoga Meet the Criteria of a Cardio Workout?
When deciding whether or not yoga is a cardio workout, you have to ask yourself if it meets the criteria for aerobic exercise.  A true cardio workout will meet ALL of the criteria.
It can be hard to make a blanket generalization about yoga when there are so many styles and disciplines under the yoga umbrella. Some are definitely not much of a workout. Others can be fast-paced and more intense.  But most types of yoga share the same poses—just done at different paces. Some of those poses use the "large muscle groups" of the body (think legs). Others don't. Holding any one pose (even though this is strength-building  isometric exercise) for more than a couple of seconds diminishes the rhythmic nature and therefore the cardio workout potential.
Other types of yoga, such as faster-paced Ashtanga or "power" styles involve fewer holds/pauses and move practitioners quickly from one pose to the next. While these involve more "rhythmic" and "continuous" movements, it may or may not be enough to elevate your heart rate to an aerobic level—depending on the class itself and your own fitness level.
Here's a related example. Walking can be a great form of exercise. Leisurely walking (what most of us do in everyday life) meets most of the cardio criteria (large muscles, rhythmic nature, continuous movement); but at an easy pace, it typically will not meet the heart rate guideline—and therefore would not count as a true cardio workout. Only walking that is brisk enough to bring up your heart rate for an extended period of time truly offers the health and calorie-burning benefits of "cardio" exercise.
A 2005 study by the American Council on Exercise looked at the aerobic benefits and calories burned by a Hatha yoga class, which is considered one of the most beginner-friendly and popular forms of yoga.  The study concluded that while the yoga group showed numerous improvements in participants' strength and endurance as well as improved balance and flexibility, they did not burn a significant amount of calories by practicing yoga. "In fact, one 50-minute session of Hatha yoga burns just 144 calories, similar to a slow walk,” according to researchers.  That's about half the number of calories that traditional forms of cardio burn in the same amount of time. Total calories burned are a good indicator of how aerobically challenging any movement truly is. The harder it is, the more your heart rate elevates, and the more calories you burn—one sign of a good cardio workout.
But this doesn’t mean that yoga isn’t worth the time, because exercise is about more than just burning calories.  It just means that you might want to reconsider swapping a yoga class for your cardio workout, and instead, use it as a complement to a well-rounded fitness routine
What about Hot Yoga?
Hot yoga can be challenging because it is taught in a room that is typically 95 to 100 degrees Fahrenheit.  At temperatures like this, you’re going to sweat—a LOT.  But sweating is your body’s cooling mechanism and not an indicator of how hard you’re working.  Some people naturally sweat more than others.  While hot yoga feels harder because the heat is challenging, that’s only because the room is warm, not necessarily because the workout is challenging enough to be considered cardio exercise. And any heart rate increase due to heat alone doesn't provide the same health benefits as moving your body in order to achieve that increased heart rate.
Some Yoga Counts as Cardio, Some Doesn't
So how do you know for sure whether or not your yoga class is a cardio workout?  Again, there are many different kinds of yoga.  Some forms (like Hatha or Kundalini) focus on gentle movements and breathing, while others are more fast-paced and physically challenging.  Your best bet is to wear a heart rate monitor, which will tell you exactly how high your heart rate gets and just as importantly, how long it stays at that level.  If your heart rate stays in the cardio zone (at least 60%) for at least 10 continuous minutes, then it can be considered cardio exercise.   This probably won't be the case for the majority of yoga routines, but it’s possible for some of the most advanced forms.  If you are new to yoga, you’ll want to start with a beginner class to learn proper form and technique so that you can avoid injury.  Then if you decide to progress to a more advanced practice, you’ll reduce your chances of getting hurt. 
This information isn’t meant to discourage anyone from trying yoga, or to say that yoga workouts can’t be challenging or aren't beneficial.  Just because a typical yoga class doesn’t have the same benefits as running doesn’t mean there is no benefit at all.  Yoga is great for flexibility, strength and improving the mind-body connection.  It develops balance, range of motion and coordination. It can boost your core strength and even improve your posture while also reducing stress.
We know that ALL movement and ALL intensity levels have health benefits and burn calories. Whether your schedule allows for one or multiple yoga sessions weekly, you’ll see a difference in how you feel when adding it regularly to your workout routine.
"Asking whether yoga counts as cardio is sort of like asking whether running can count as yoga," says SparkPeople's Coach Nicole. "Traditional forms of exercise like strictly defined cardio and strength training are what we measure other things against; but that doesn't mean exercises that don't 'fit' aren't any good. Some types of movements are in a league all their own. Yoga, like other mind-body exercises, offers documented health and fitness benefits despite the fact that they don't meet these clinical guidelines." The important thing to remember is that we all need a variety of exercises for best results. No one type of workout can truly be everything.
Do you think yoga counts as cardio? How has yoga benefited your health and fitness level?