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Jim Talk

Jim Stoppani PhD

Jim Stoppani, PhD, earned a doctorate in exercise physiology with a minor in biochemistry from the University of Connecticut (Storrs) before serving as a postdoctoral research fellow at Yale University School of Medicine. In 2002, he was awarded the Gatorade Beginning Investigator in Exercise Science Award by the American Physiological Society for his groundbreaking research. For the next 10+ years, Dr. Stoppani served as Senior Science Editor for Muscle & Fitness, Muscle & Fitness Hers and FLEX magazines at Weider Publications. In 2013, he created his breakthrough sports nutrition company JYM Supplement Science, which now includes a line of eight top-selling products.

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The Biomechanics Of Bigger Biceps

Two techniques in particular—seated curls and cheating curls—can help you take advantage of the strongest part of your curl for greater gains in size and strength.

Every exercise you do has a “strength curve” through its range of motion, which tells you the parts of the movement that are strongest and the parts that are weakest. With a biceps curl, the strength curve dictates that you’re weakest at the beginning of the curl, where the arms are fully extended, and then you get stronger as you lift the weight up. Right around the halfway point of the curl is where you’re at your strongest, and then your force production decreases from the halfway point up to the top of the curl—almost like a bell curve.

This is due to both the anatomy and the biomechanics of themuscles that initiate the curl—and we’re not just talking about the biceps here. The brachioradialis andbrachialisattach lower on the upper arm bone andthus arebetter at initiating the movement because it'sa shorter lever arm. Problem is, these two muscles are very weak. When you get to the halfway pointof the curl, the biceps (a stronger muscle than the other two) start kicking inand force productiongoes up.

Sowhy isallof thisimportant? Because you’re only as strong as your weakest link.And in this case, your weakest linkis that very first part of the curl. You may be strong enough to lift 150pounds from the midpoint of the curl (forearms around parallel with the floor on a standing barbell curl) to the top, but if you’reonly able to lift 100 pounds from the bottom position up to halfway, guess how much weight you’re going to be forced to use on strict curls? That’s right, 100 pounds. In thisexample, you’re essentially shortchanging your biceps 50 pounds at their strongest point and potentially leaving some size gains on the table.

The solution, then, is to not always do strict curls in your biceps workouts. And there are two techniques in particular I recommend for doing thisand taking advantage of the strength curve of the biceps: seated barbell curlsand cheating curls. With both of these variations, you’re essentially eliminating the weakest portion of the curling motion. With seated curls, the bar isn’t able to go down to full arm extension because your legs are in the way,and with cheating curls, you’re using momentum to get past the weak part of the ROM.

Granted, I don’t recommend using these techniques in every biceps workout, because strict, full-range-of-motion curls are still superior for balanced development and preventing injury. But incorporating seated and cheating curls in your biceps training on a regular basiscan definitely help you build bigger biceps by maximizing overload in the strongest portion of the curl.

How-To: Seated Barbell Curls

Sit on a flat bench with a loaded barbell resting on your thighs. Make sure the barbell is loaded with significantly more weight than you’d normally use on standing barbell curls. With a shoulder-width, palms-up grip and your torso perpendicular with the floor, curl the weight from your thighs as high up as possible. Slowly lower the weight back down to your thighs,but don’t let it come to a complete reston your legs; just taplightly and go into the next rep.

How-To: Cheating Curls

As with seated curls, choose a heavier weight than you normally would on curls. But here, you’re doing standing barbell curls. From the start position (arms fully extended toward the floor), lean forward with your torso and then back (in other words,give it some “body English”) to create enough momentum to get the bar moving upward. Once it’s moving, stop the cheating about halfway up and finish the curl using only the biceps.


  1. In a given biceps workout, do only one of the two above variations (not both).
  2. Make sure your biceps are thoroughly warmed up beforehand, since you’ll be using significantly heavier weightthan normal. I would even recommend doing seated or cheating curls as your second biceps exercise in the workout.
  3. Whichever variation you choose, perform 3 or 4 sets of 6 to 10 reps, giving yourself ample rest between sets (2 to 3 minutes).
  4. Finish your biceps workout with one or two other full-range-of-motion strict curling exercises.