ANNOUNCER: Bicep curls can be a great way to build strength and sculpt your upper arms. Or they can be a major time waster. Take a look at these two versions. Fitness expert Jonathan Cane explains why A is more likely to build your ego, not your muscles.
JONATHAN CANE, EXERCISE PHYSIOLOGIST: Typically, what you see people do is they'll just sort of swing the weight, get it moving down at the bottom and then the momentum will just sort of carry through and they're really not having to use their muscle very much to get through that last part of their range of motion.
ANNOUNCER: Besides wasting time, bad form can also lead to injury.
JONATHAN CANE, EXERCISE PHYSIOLOGIST: You're at far greater risk to hurt your lower back, to hurt your -- to hurt your elbow, to hurt tendons, to hurt your shoulders.
ANNOUNCER: Here's how to do bicep curls the right way.
JONATHAN CANE, EXERCISE PHYSIOLOGIST: We're going to go full range of motion, all the way down at the bottom. He's going to keep the elbows tucked in so that we're not using the shoulder joints and really focusing solely on the biceps which really are just moving the elbow joint. The pelvis is neutral. He's not throwing the pelvis forward or arching his back, knees are soft.
ANNOUNCER: Eliminating momentum makes your biceps work harder.
JONATHAN CANE, EXERCISE PHYSIOLOGIST: So you eliminate momentum by going in a slow, deliberate fashion, three seconds up, three seconds down. You don't hold your breath. Holding your breath makes it easier, but it also makes it less safe.
ANNOUNCER: And remember â€“ proper form is more important than how much weight you lift.
JONATHAN CANE, EXERCISE PHYSIOLOGIST: By doing that, yeah, you may have to sort of, you know, check your ego at the door and use a little bit less weight, but the target muscle is going to get a lot more benefit out of the exercise.
ANNOUNCER: Thanks for joining us on today's Once Daily.