This is a common mistake, especially among highly competitive people. Everyone likes the idea of putting the big plates on the bar and everyone wants to impress their fellow gym rats.
But you should never let your ego stand in the way of a good workout — and as it turns out, Dowd says, lower weights and higher repetitions will often deliver better muscle growth than higher weights and fewer repetitions, or worse, higher weights and poor form.
“The key to muscle growth is actually total volume, and the formula for volume is weight times sets times repetitions,” she explains. “So, doing higher repetitions with less weight will equate to greater muscle growth, though there is a limit on how light you should go for optimal results. Using weights that are 65 to 80 percent of your max should make up the bulk of your training volume, with the occasional foray into heavier weight to test yourself.”