Your reps are all wrong.
When you strength train, you may be tempted to do the standard three sets of 10 to 12 reps for every exercise, but that thinking may be holding you back, says Chicago-based personal trainer and running coach Meghan Kennihan. “While research has shown the optimal number of reps for maximizing muscle growth is about 6 to 12 reps per set, this doesn’t mean all of your training should look like this,” she says. Incorporate some lower rep ranges (say, 1 to 5 reps per set) using heavier weights as well as higher ones (which might include up to 18 or 20 reps) using lighter ones, says Kennihan. “This variety of repetitions is important for optimizing muscular development” because it keeps your body on its toes which helps you avoid hitting an exercise plateau.
You’re not eating enough carbs—or calories in general.
For Maria-Paula Carrillo, MS, RDN, a registered dietitian nutritionist in Allen, TX, a big part of her job is reminding clients that in order to build muscle, focusing on protein intake alone isn’t going to help. By overdoing it with protein, “there’s a good chance you won’t get sufficient carbohydrate intake, which is essential when you’re trying to build muscle,” she says. Carbs are not only essential to fuel your workout, giving you more energy to work hard enough to actually build muscle, but they also help rebuild muscle tissue—which is a crucial part of muscle growth, she says.
Your workouts lack variety.
Doing the same chest presses and kettlebell squats every other day? If you perform the same routine over and over again, there’s a good chance you’ll hit a plateau in your training, says Brandon Mentore, a strength and conditioning coach and sports nutritionist in Philadelphia. “You have to vary the stimulus to trigger muscle growth,” he says, “And the best way to do that is with different exercises, angles, and loads.”
You’re doing too much cardio.
While cardiovascular exercise that gets your heart rate up is a crucial component of any exercise routine, overdoing it on the running, Spin classes, swimming, or other cardio exercises can actually burn hard-earned muscle tissue, says Mentore. Katy Fraggos, also a personal trainer, suggests scaling back your cardio workouts to 2 days a week if you’re having trouble putting on muscle. “It seems counterintuitive, but this can really help speed up your results,” she says.
You’re not lifting heavy enough weights.
Building muscle is a significant biological shift that requires enough stimulus to trigger that shift, says Mentore. “This means you have to add intensity to your training to trigger the body to build muscle,” he says. The key: Really pushing yourself, adds Shaun Zetlin, a personal trainer in New York City. “It doesn’t matter how many times a week you exercise or how consistent you are, if you’re not challenging yourself in your workouts, you’re not going to build muscle,” says Zetlin, who recommends lifting a weight you can handle for 6 out of 8 reps, with the final 2 reps being extremely challenging to lift. Do 3 sets of each exercise you do like this, resting 90 seconds at most between sets, says Zetlin.
You lack body awareness during your workouts.
If you think a mind-body connection is only important during activities like yoga, think again, says Geoff Glaeser, a personal trainer and group fitness instructor in Los Angeles. “An inability to mentally fire muscles can really hold you back,” he says. Next time you’re lifting weights, really focus on the muscles you’re working by bringing your mental attention to that area of your body. Doing so will help you focus on performing the exercise correctly, which means you’re more likely to work your muscles until they’re fatigued—which is essential for muscle gains. As you’re learning how to do this, Glaeser recommends lifting very low weight and doing more reps, and incorporating active and static stretching—like yoga—into your routine.
You’re not getting enough rest.
If you don’t get enough sleep, train too frequently, or don’t take rest days between workouts, you’ll seriously hinder your ability to build muscle, says Mentore. Coen S. Hewes, a personal trainer and nutritionist in Sydney, Australia agrees: “To build muscle, the body needs to break apart fibers inside the muscle, and then grow back more or different types of muscle fibers in their place,” he says. “Without enough rest, the muscle doesn’t have time to repair and grow.” Aim for around 8 hours of sleep each night, and weight train 3 days a week, taking rest days in between each workout, suggests Hewes.