8 Cardio Myths It’s Time To Stop Believing

Cardio is a bit of a controversial subject in the fitness world. On one end you’ve got endurance die-hards who swear by the benefits of a nice, long run, and on the other end you’ve got strength training enthusiasts who limit cardio as much as they possibly can. Even if you don’t have a hardcore cardio opinion, you’ve probably got a few questions about this often-misunderstood form of exercise!

We asked three fitness experts to clear up the cardio confusion so you can save yourself time, energy, and loads of motivation. You’ll work out smarter, protect your health, and charge towards the results you really want.

Myth 1: Doing tons of cardio is the best way to lose weight.

When we want to lose weight, we think about burning as many calories as possible—and logging endless miles on the treadmill or flights of stairs on the stair-master seems like the way to do it. Though traditional cardio workouts will help you create a daily calorie deficit, they’re not your best bet long-term, says Lisa Niren C.P.T., head trainer of CITYROW in New York City.

The more lean muscle mass you have, the more calories you burn even at rest—meaning you contribute to that caloric deficit just by living—and to really build that muscle, you need to strength train. Cardio can actually burn both fat and muscle, so doing too much can actually decrease your muscle mass, slow your metabolism, and undermine your ability to lose weight, Niren says.

Related: Why Cardio Is NOT The Best Way To Lose Weight

A workout routine that supports lasting weight loss combines regular strength training (about two or three days per week) with some high-intensity cardio like interval sprints or kickboxing, suggests Christi Marraccini, C.P.T., head coach at Tone House in New York City.

Myth 2: You need to do at least 30 minutes of cardio for it to be worthwhile.

Any movement you can squeeze in does your body good, so don’t throw in the towel and stay on the couch just because you’ll only have 20 minutes to sweat. Maximize the health benefit of short cardio workouts by pushing yourself to keep your heart rate elevated to 70 to 85 percent of your max heart rate (220 minus your age) for at least 10 to 15 minutes, says Hannah Davis, C.S.C.S., creator of Operation Bikini Body Abs. Working at this intensity will help improve your aerobic capacity and burn more calories.

To really maximize your workout’s calorie-burning potential, swap steady-state cardio for high-intensity interval training (HIIT). Because HIIT involves bursts of intense effort, you’ll burn more calories in less time (and in the hours after you finish) than you would with steady-state cardio.

In HIIT workouts, you’ll alternate between bursts of all-out effort (they can last anywhere between five seconds and a few minutes) that rocket your heart rate to between 80 and 95 percent of your max and recovery periods that last long enough for your heart rate to drop back down to between 40 and 50 percent of your max, according to the American College of Sports Medicine. You can do HIIT workouts on cardio machines, or use bodyweight movements like burpees, jump squats, box jumps, and more.

Myth 3: You should do cardio every single day.

We’ve said it once and we’ll say it again: if you want to lose weight, your workout routine will need to emphasize strength training, not just cardio! Plus, even if weight-loss isn’t your goal, hitting cardio every day can backfire. Why? When you work out, you break down your muscles so that they can rebuild to become even bigger, stronger, and more capable. To do that, though, your body needs ample time to recover.

Pushing yourself to exercise every day can actually lead to overtraining, a state in which your body doesn’t have enough time to recover and rebuild muscle, and you experience issues like muscle breakdown, fatigue, and moodiness. That’s why Marraccini recommends one to two days of active recovery per week.

Supps That Support Recovery

If you’re feeling uncharacteristically unmotivated, moody, tired, or sick, skip the cardio and take an active recovery day instead.

Myth 4: Yoga doesn’t count as cardio.

Yogis will be glad to know that according to research published in the European Journal of Preventive Cardiology, yoga can provide benefits similar to those of traditional lower-intensity cardio workouts, like decreased risks of metabolic syndrome, high blood pressure, and poor cholesterol, as well as improved triglyceride levels and lower body mass.

Not all yoga classes are created equal, though. If you want to swap your light swim, walk, or bike ride for yoga, look for a class described as ‘power, ‘fast,’ or ‘hot,’ which will be more intense and boost your heart rate, according to yoga teacher and ICE NYC mobility instructor Gabrielle Morbitzer. At the end of the day, though, while can sub yoga in for lower-intensity workouts, it won’t have the same body and fitness effects of more vigorous workouts, like HIIT.

Myth 5: Fasted cardio torches the most fat.

If your body doesn’t have any calories from food to burn for exercise, it’ll dip further into your fat stores to power you through, right? As logical as the theory might sound, it’s not quite true in practice. Research shows that people burn the same amount of fat during steady cardio regardless of whether or not they ate beforehand. Plus, research has also shown that skipping a pre-workout snack can increase muscle breakdown, which sabotages your metabolism and ability to burn fat.

To perform at its best, your body needs fuel—so when you work out on an empty stomach, you may not be able to push yourself as hard. “That means your intensity may drop and your calorie burn ends up being lower than it could have been,” says Davis.

If working out first thing in the morning works best for your schedule, stick with it—but don’t force early-A.M. workouts or starve yourself before hitting the gym in the name of fat-burning. If you have time, eat a snack that contains some carbs and protein about an hour before getting sweaty.

Myth 6: You have to stay in the ‘fat-burning zone’ to burn fat.

The ‘fat-burning zone,’ which you’ve probably seen identified on cardio machines as being between 50 and 65 percent of your max heart rate, sounds like the place to be if you want your cardio workouts to help you lose weight. When you work at this intensity, you primarily use your aerobic energy system and burn fat for energy, explains Niren. Though a higher number of the total calories you burn will come from fat, you burn far fewer calories than you would exercising above your aerobic threshold, at 70 to 80 percent of your max heart rate. The higher the demand you put on your muscles, the more damage you inflict and the harder your body has to work to recover (all of which takes calories), says Davis.

Myth 7: You can skip leg day if you do cardio activities like cycling and running.

Cardio lovers and marathoners who avoid the squat rack, know this: Traditional cardio doesn’t build muscle or challenge your muscles through a full range of motion—both of which prevent injury—like strength training does. In fact, when you focus just on cardio, your body adapts and requires less and less energy to get through your usual routine over time—leading you straight into a plateau. While this is good news if you need to ration energy to get through a marathon, it’s bad news if you want to lose weight or build strength, says Niren.

Related: 6 Reasons You Should Never Skip Leg Day

Incorporate leg-strengthening exercises like squats, deadlifts, and lunges into your workout routine regularly in order to burn more calories, build strong legs, and lose weight more efficiently.

Myth 8: You should always do cardio before strength training.

Everyone and their mother has their own ideas about how you should structure your workouts, but whether you hit cardio or weights first really depends on your goals. “If you’re training for a race, I recommend doing cardio before strength” says Davis. In that case, your cardio pace and performance are higher priority than how much weight you use in the squat rack. If you’re not training for anything, though, strength train first so you’ll be as fresh as possible to lift heavy and maintain proper form and technique, Niren says. Plus, if you’re trying to lose weight, you’ll use glycogen fuel your strength training and more likely to burn fat for fuel during your cardio.