Physical therapists debunk 14 more myths about exercise and fitness

• Physical therapists Dr. Wesley Wang and Dr. Stacie Morris debunk myths about fitness and exercise.
• They explain why you can't outrun unhealthy eating and how big muscles aren't necessarily stronger.
• They also debunk the entire concept of trying to get "in shape" or "toned."

Following is a transcript of the video.

Stacie Morris: "Working out tones your muscles." [laughs] I can't even say that with a straight face.

Wesley Wang: "The best way to burn fat is on an empty stomach." Yeah, go ahead and crinkle that up and throw that one away as well.

Morris: "Running will destroy your knees." Even though I hate running personally, it will not destroy your knees.

My name is Dr. Stacie Morris. I am the owner of The Physio Fix, which is in Phoenix, Arizona. I have been practicing physical therapy for six years now, and my specialty is working in sports, but specifically working with strength athletes and gymnasts.

Wang: Hi, my name is Dr. Wesley Wang. I am a physical therapist, and I have been practicing for about five and a half years now. I personally specialize in ACLs and working with high-school- and college-level athletes, and I work at Healthy Baller.

Morris: Today, we're debunking fitness myths. "Your knees should never pass your toes when squatting."

Wang: This is something that I maybe pushed a little bit early in my career, when I didn't understand everything.

Morris: You should allow your body to move naturally, and if you limit that, you actually add more stress, as we've known through literature, to your hips and your low back. So to limit that movement is just absurd to me, and I feel like that myth needs to die now.

Wang: You think about the daily things that we do. Let's take away strength training. Beyond that, you go down the stairs, your knees go past your toes. When you play your sport, do you ever think about your knees being past your toes? And the answer is 100% no. And, Stacie, for you, you were a gymnast. When you did your jumps and flips and landings, I can guarantee you were never like, "Oh, no, my knees cannot go past my toes."

Morris: You're absolutely correct. So now we see so many ankle limitations because of this movement pattern that people have been spreading a myth or trying to teach for the wrong reasons, without letting them just move like athletes. Let your body move natural, and usually it does what it needs to do to be most efficient at whatever movement that is.

Morris: "Soreness is a sign of a good workout." Soreness is basically when you have an accumulation of lactate in your blood. It turns yourself into more of an acidic state, and that's when you kind of feel that burn effect that people talk about.

Wang: Is soreness a factor of a workout? Yes, potentially. Our patients, our athletes, have had plenty of great workouts and not felt sore the next day. Right? It's just the way the body is, and sometimes you just have a harder workout, a shorter workout. So those 15-, 20-minute workouts, those are the ones that typically I don't personally feel too sore in, but if I get, like, a nice hour-and-15 workout where I'm just going hard at it, then I'm going to feel a little bit more sore the next day. But, again, that doesn't mean that my 20-minute workout was ineffective or bad.

Morris: A lot of people, they're like, "I can barely walk, I'm so sore." And their trainer is like, "Good." And I'm like, that's not so good! You should be able to walk. You should have been progressed in a way that was so gradual that you are feeling stronger, and maybe you are still getting a little bit sore, but you don't feel like you can't walk the next day.

Wang: I think rest and recovery, nutrition, sleep is super important.

Wang: "Bigger muscles are stronger."

Morris: From a physiology standpoint, bigger muscles may have the ability to be stronger. They could have bigger or more motor units to be able to get stronger. But that doesn't necessarily mean that they are stronger. There are people that have genetic differences, they have longer muscles, and they're not going to be as short or as prominent. So they maybe don't look as big, but they may be really, really strong because there's more of them and there's a shorter tendon where they're attaching. Or, there's people that have different limb lengths. Your levers are going to play into how strong you are.

Wang: I do talk about size, because obviously dealing with the rehab side of things they have a post-op knee that looks like half the size of the other side, but I'm never like, "Oh, you're weak because you look like this." It's just, "Hey, let's get in the weight room, let's get a little bit stronger, let's make sure you can perform your sport safely, confidently," and all that kind of stuff. And for me, that's all I really care about, is more the performance side of things, and getting stronger is going to help you in your performance level, for the most part.

Wang: "You need to eat meat to build muscle." [laughs] Your eyes got big there. Definitely not.

Morris: You do need to eat protein to build muscle, but you do not need to get your protein from meat sources only. They have vegan protein shakes. You can do lentils. Even quinoa has protein in it.

Wang: "Cardio before weights." What are your thoughts?

Morris: So, it depends on your goals. Are your goals cardiovascular-related, or are your goals strength-related? I think that that thing needs to be first. So if you're a strength athlete, you definitely need to make sure that you're focusing on what's important, which is your strength training.

Wang: And this is not a black and white thing, just like a lot of things in the fitness world and rehab world that we work with.

Morris: Cardio doesn't have to be what you think it is. It doesn't have to be biking or running or swimming. I do weightlifting as a form of cardio because I get my heart rate up and then I'm able to sustain that, and that alone is cardiovascular work.

Morris: "Working out tones your muscles." [laughs] I can't even say that with a straight face, because what is toning? I think of toning as something a printer does. I think when people think of tone, they think of seeing their muscles and it being visible, and it always comes down to calories in versus calories out. And being able to see your muscles means that you probably are in a caloric maintenance or deficit state, so you've got to make sure you're really focusing on what you're eating too, not just focusing on what you're doing in the gym.

Wang: There are plenty of runners out there who dread lifting, but they're still considered on the toner side. And that's where the word tone is very, very subjective. But there are other people who are on the more strength-conditioning side who love to lift and are also toned. So, again, that's where the individuality really needs to come into play here.

Morris: Absolutely. It's all going back to their goals. What are your goals? And for me, my goals are not as much aesthetic anymore as they are just feeling strong, being strong, and being the best version of myself.

Wang: "Exercise cancels out unhealthy eating habits." Definitely not. [laughs] 100% not.

Morris: My sister used to say this all the time. She'd be like, "I'm going to work out today so I can go to McDonald's." And I was like, "What? If you're eating lots of saturated fats and processed food, it's not good for you." And she was like, "But I'm burning more than I'm consuming. Isn't that what matters at the end of the day?" And I was like, "Yes, that's important, but it really comes down to the things that you're putting inside your body that's going to have a long-term effect." It's not just calories in versus calories out. Let's hit your macros in these different three areas, like the big protein, carbs, and fats, whatever that is for you.

Wang: Can you have your occasional cheat burger and things like that? Of course you can. 'Cause if I were to go eat fast food, whatever one it is, for 14 of my lunch and dinners, and I could lift two hours a day, that would not necessarily help me.

Wang: "You should bulk and cut to build muscle." I have done a stint of bodybuilding, and I know that this is something that I used to also believe before I became more knowledgeable on the subject. Usually bodybuilders, they will bulk up, just to put on some muscle, and then they will cut down, so then they can see that muscle and see what that muscle looks like. Now, if your goal is not to be a bodybuilder and you want to bulk and cut simultaneously, you can do that. But you have to be in a positive nitrogen state in your body, and the way that you can achieve that is by increasing your protein in the form of amino acids and also adding in creatine and then making sure you're sleeping enough. It's not easy putting on mass and then taking off mass, because then you're like, "Man I look so good when I'm cutting, but then I feel terrible when I look in the mirror when I'm bulking." And it just throws you into this emotional state of not feeling good about yourself. I see that in some of my patients too. They don't know how to return back to normal eating, because they've been in either one or the other for so long.

Wang: I think that for people who are really trying to be structured and rigid with this, there is so much help out there. I know Stacie takes on online clients and things like that to do it in a safe, productive, structured way.

Wang: "You need to work out for at least an hour for it to have an effect." Please go ahead and rip that one up as well.

Morris: I'm a big believer in working smarter, not harder, and shorter doesn't mean not effective. The ACSM, they have those minimum effective dosage numbers for adults, right? Over the course of the week, you have to accumulate that many minutes of moderate intensity for it to be considered effective for your cardiovascular health. And then if it's vigorous activity, I think it's 75 minutes to 150 minutes, so it's even smaller.

Wang: Can you only survive on 20-, 30-minute workouts? Yeah, you can, but I think that obviously you can get significantly more done in a little bit more time, which is, I think, the hour time frame.

Morris: "Running will destroy your knees." You can rip that one up too. Even though I hate running personally, it will not destroy your knees. I don't know who made that up or when that became a thing, but it's definitely not backed by any scientific research, and I know I've read some recent studies actually show that runners have thicker density of their cartilage and their ligaments, so actually running helps their knees. It does not hurt your knees.

Wang: Yeah, we talk about how strength training helps to build resiliency in your tissues, and running, it actually does the same. I was laughing when I read this just because I grew up playing basketball. Running is involved in basketball. I work with a lot of soccer and lacrosse players. They have to run, and I can promise you that all their knees are not destroyed. I think that the people who do have pain with running, that probably means that their body and their tissues just aren't used to whatever the capacity they're doing.

Morris: It's more of, did you start progressing your mileage too fast? Bumping up your intensity of other things too fast and your body wasn't ready for it? Did you change your shoes recently and now your foot has to move in a different way? All of those little things kind of add up.

Wang: "The best way to burn fat is on an empty stomach." Yeah, go ahead and crinkle that up and throw that one away as well. [laughs] Your eyes got big, Stacie.

Morris: So, this is one of those ones I used to believe too. They've come out with a bunch of new studies to show that, no, you do not have to do fasted cardio to burn fat. Obviously if you're in a caloric deficit, you're in a caloric deficit, and then you're going to be burning fat. It's more like, what kind of workouts are you doing? What heart rate zone are you in? And then what does your nutrition look like?

Wang: The intensity probably matters as well. We train a lot of these high-school- and college-level athletes, and they're coming in and they're sprinting, they're cutting, they're lifting. We typically recommend them eating something before they come in, even if it's, like, a granola bar or something like that.

Morris: Eating breakfast is fine. Not eating breakfast, if you don't want to eat breakfast, that's also fine, but just make sure you're eating what you need to be eating and getting the nutrients you need to get throughout your day.

Wang: "Lifting heavy weights at a young age will stunt your growth." I think that, Stacie, you and I would both agree that this is something that maybe we grew up on.

Morris: There's no evidence to support that viewpoint, that lifting weights is going to stunt your growth. I've looked into it, because I started lifting at a younger age. I'm actually pretty tall for a gymnast.

Wang: I think strength training does play a big role in youth sports and keeping them healthy and keeping them strong. And I also think people automatically assume that strength training means that you're lifting extreme heavy weights, when that's not the case. Picking up a 3- to 5-pound weight is considered weight training and strength training.

Morris: "Assisted exercises are not as effective." My immediate thought is, not as effective as what?

Wang: Does assisted mean that you're just getting some help? Does it mean that you're using bands?

Morris: Maybe a lot of people have a hard time doing pull-ups, and they use a band. But does that mean that they're not getting stronger, because they're using a band? No. It just means that at their current level they need a band to be able to perform the movement. Sometimes we do assisted mobility work, so we use a band to assist in doing this specific position. It's actually going to help us in the long run by using some assistance right now. It all comes down to, what's the goal of the exercise? Are we trying to get more mobility or get stronger? Because, yeah, sometimes using assistance is what we need to use.

Morris: "You can't exercise with flat feet." This is just plain silly. This is so silly. Oh, my gosh. There's, like, half of the people in the world that have flat feet. They're not supposed to exercise?

Wang: I'm done. I'm done. I quit. You definitely can exercise with flat feet. I, along with hundreds of thousands of other people, millions of other people, have been able to do it.

Morris: And I think it's also kind of funny that a lot of people still believe that you can change your foot shape and your arch of your foot. If you have flat feet, your foot structure kind of is how it is, and, yes, we can get the arch of our foot stronger, so then you can have better stability overall, but you can't change the structure of your foot.

Wang: At the end of the day, all these myths that we've talked about today are because of extremes. Don't be afraid to question things if someone's telling you that you definitely have to do it.

Morris: If you start believing that myth and now telling someone else, this is how myths circulate and travel. If one person becomes more educated, then they can start breaking that cycle right then and there.