This Is the Secret to Picking the Best Weights to Build Muscle

IF YOU’RE AIMING to build muscle, you know you need to hit the weights. But exactly how heavy (or light) should you be training?

Whether you’re getting your workouts off Instagram, or from your favorite trainer’s website, or you’re running a split from your best friend, you’ll need to choose just the right weight. Too heavy, and you risk injury. Too light, and you won’t truly spark the muscle-building gains you want. Because sure, you may get winded during your work sets. But if you’re not truly pushing your limits, you’re leaving muscle and strength advances on the table.

How do you choose the right weight? After a few warmup sets, aim to choose a load that makes you a bit unsure of whether you can actually complete all the reps (yes, really) on your working sets. “You should have a little bit of doubt whether you can complete [your last few reps],” says Ebenezer Samuel, C.S.C.S., Men’s Health fitness director. A good gauge of whether you’re training heavy enough is the speed of your reps. On those final two reps of any set, the load should be so heavy that you can’t drive the weight upwards as quickly as you could earlier in the set. If the weight doesn’t slow down, you went too light.

This idea helps you work toward progressive overload, a key principle discussed in our new deep-dive Muscle-Building guide, available to MVP subscribers exclusively. To build muscle, you have to apply significant stress to your muscles to force them to grow. Lower intensity means less growth is required for the muscles to adapt to the strain being applied to them. You have to be progressively overloading the muscle.

If you complete a set with perfect form, you should be upping your weights. If you’re working on an upper body exercise, the NSCA suggests trying to add 2.5 to 5 pounds after you’ve done a set with perfect form. For a lower body exercise, try tacking on 5 to 10 pounds of extra weight.

That extra load may present a little bit of self-doubt that you can get the work done. Don’t be scared of that doubt—it means you’re pushing yourself the way you should if your main goal is to build muscle. During major compound lifts (like bench presses and shoulder presses) have a good spotter on deck and safety bars set, just in case you do start to fail.

But no matter what, be willing to pick up a load that doesn’t just give you a pump, but gives you just a bit of uncertainty about whether you’ll be able to hit your reps.

“If you know you can complete them, you did not go heavy enough or train hard enough. You should always have a little bit of doubt,” Samuel says.