An Expert Explains Why You're Probably Using the Wrong Weights

POPSUGAR Photography | Diggy Lloyd
POPSUGAR Photography | Diggy Lloyd

Cardio is great for burning calories in the moment, but you need a resistance component to strengthen your muscles and reap those metabolic burn effects for hours following the workout. Plus, when you have more muscle, you can burn more calories during the day naturally.

Strength training is really important as we age, as it can build bone mass and create lean, defined muscles, which can reduce risk of osteoporosis and injury, Rebecca Gahan, C.P.T., owner and founder of Kick@55 Fitness in Chicago, told POPSUGAR.

But what if you're using the wrong weights? Turns out, you could be negating all the positive effects from your workout, and you might even find yourself sidelined for a while if you end up hurting yourself. Here are a few ways to know if it's time to switch out those weights for a better, safer, more effective workout.

Your Reps Either Feel Too Easy or Too Hard

You shouldn't feel so fatigued that you're dropping weights on the ground (or your foot — ouch) at the end of the set. Yet, if you're breezing through those rep counts, it's time to increase.

"If you can complete 15-20 reps without struggle, it is time to go up in weights," said Gahan. Likewise, if you can't get through a solid 10 reps without feeling like you're going to crash on the floor, it means those weights are too darn heavy, according to Gahan. A tip? "You should feel almost maxed out by the end of 15 reps, but still be able to complete them with good form," she said. So you should really feel those last two or so reps, but in a good way.

You're Not Using the Right Form

First and foremost, always pay attention to your form. Give that mirror some love and check yourself out. If you're not doing the right form, it could be because you never learned how to do it right, which you can easily fix by asking a trainer for help. But it could also be that you simply can't withstand the intensity of the weights you're using, said Gahan, or that the weights are so light that they don't offer enough resistance to maintain form. Switch up the weight and see if it makes a difference.

You Stopped Seeing Results

With each upgrade in weights or new technique, you should be able to consistently shock your muscles and get leaner and stronger. However, if you've stopped showing progress, it means you're no longer challenging yourself to your max potential, said Gahan.

"When you do not increase your weights at the appropriate time, you no longer challenge the muscle. Thereby the muscle does not break down, build back up, and create real definition," she explained. If you exercise all the time but are lacking lean muscle mass, you could start to break down the muscle you do have, which will decrease your metabolism and strip away all that hard-earned progress from lifting. Not good.

You're Getting Injured

If one day your shoulder hurts and then the next your back, almost as if you're jumping from one injury to the next, it could mean you're using too heavy of weights and putting excess pressure on your bones, joints, and muscles, Gahan said.

Translation: You're going to feel sore a lot and you might turn overuse of a muscle group into a full-blown injury, which obviously can derail your workout stride, she added. "If you consistently lift too heavy of weights, you put yourself in danger of hurting yourself because you are most likely using improper form," she said. Plus, you're putting excess strain on areas that simply aren't quite ready to be used yet.