This article is sponsored by our partner, MitoQ.

When it comes to gym time, it’s pretty easy to fall into a routine and start to swear by certain workout rules. Newbies and fitness fanatics alike—whether you’re into running or powerlifting or something in between—tend to stick to what they think are secrets for training success. But some of the most widely held beliefs about what you should do in and out of the gym (and what you shouldn’t) aren’t totally true. Read on for seven of the most pervasive workout and fitness myths out there, with expert insight about what you should be doing instead, no matter your fitness goals. 

Fitness Myth #1: Strength training will make you bulky

This is one super-popular exercise belief—especially among women who want a slim, toned physique. But it’s a complete myth. For one thing, your muscles might look bigger immediately following a strength session, but that’s just a temporary pump that’s going to go away within a few hours. For another, there might be other factors making you “big.” 

“Part of the reason people continue to believe this is that they’re probably doing things outside the gym that lend themselves to getting big,” says Gunnar Peterson, celebrity trainer and director of strength and endurance for the NBA’s Los Angeles Lakers. For instance, “When women feel like they’re getting bigger, it’s usually not about increased muscle size but that their appetite is going up and they’re eating more than they should be eating.”

To truly get bulky from lifting weights takes a ton of weight-room dedication (not to mention possibly supplements or anabolic steroids). “Getting big is a lifestyle; you have to reach technical failure in your lifts, in a rep range that most people don’t do, and eat calories above and beyond what you need,” says Peterson. Plus, testosterone is a necessary component, and women on average have only 5 to 10 percent as much testosterone as men—so it’s much more difficult for them to grow muscle size.  

Fitness Myth #2: Cardio blasts the most calories

Many people seriously overestimate how many calories they burn in a workout, especially when it comes to cardio. One reason: the tickers on cardio machines, which are totally unreliable for tracking your burn. “That machine doesn’t know you, it doesn’t know your lean-mass-to-fat ratio, and it’s working off an algorithm,” says Peterson. “It’s just a ballpark.” 

Plus, the effectiveness of a workout isn’t just about the calories you burn during the workout itself. The term EPOC, or exercise post-oxygen consumption, refers to the number of calories you blast afterward—and studies show you burn more post resistance training than you do post cardiovascular workout. 

Fitness Myth #3: Running will wreck your knees

This common belief might be completely false, according to recent research. A 2015 study found less inflammation in recreational runners’ knees than those of non-runners. Another study found that people who pound the pavement are less likely to have knee osteoarthritis than non-runners.

Fitness Myth #4: You should always stretch post-workout to recover faster

It’s pretty common knowledge now that stretching before you break a sweat isn’t the key to a better workout (and could even leave you injured if you try to stretch without warming up). Many people, though, still swear by a post-exercise stretch session. It can help you calm down your body and mind, yes, but will it help you bounce back faster? Not necessarily. Research on the topic is inconclusive. “If it feels good, do it,” says Peterson. “Just make sure to never stretch cold.” If you don’t love it, feel free to skip; it likely won’t harm your performance. 

Fitness Myth #5: Fasted cardio burns more fat

Doing your run, bike, or rowing session on an empty stomach—aka fasted cardio—is a trendy way to work out. Is it as magical as it’s made out to be? 

“The theory behind it is that glycogen stores are depleted, so you’re burning fat as a primary fuel source,” explains Peterson. “But when you haven’t eaten, energy and duration by necessity are both lower—meaning you can’t go as hard as long.” Simply put, you get as big a burn when you work out in a fasted state as you do in a non-fasted state. 

Fitness Myth #6: You should sip a calorie-free sports drink

Whether you’re just trying to shed a few pounds or aiming for peak performance, reaching for an energy drink packed with sugar and calories seems like it’ll just sabotage your exercise efforts. But no- or very low-calorie options aren’t necessarily the way to go either. “You can’t have a no-calorie energy drink—energy is a caloric measurement,” says Peterson. Instead of higher-calorie sips, though, he recommends a supplement like MitoQ, which helps keep the energy-producing mitochondria cells in your muscles charged to sharpen your competitive edge. “Energy is produced in the mitochondria of the cell and MitoQ is going to help keep that mitochondria fresh. I’d go to that before I go to a sugary [energy] drink. I’d make sure I was doing what I could on a cellular level so I get the most out of my workout. It’s such a safe way to make sure my foundation is laid.” 

Fitness Myth #7: Unless you’re training hard for something, you can skip cross-training

Yes, 20 minutes on the elliptical a few times a week or a quick jog whenever you can fit one in are both better than nothing. But no matter how low-key your cardio, if you’re doing the same workout every outing and never mixing in strength training, you’re setting yourself up for potential pain down the road. 

Cross-training doesn’t mean you have to hit the heavy free weights, notes Peterson. “You need to add in some kind of resistance training, but it can be something like Pilates or yoga,” he says. “To only do cardio [means] you’re leaving some stones unturned.”