Achieving more biceps thickness
I'm very late to this thread, and actually stumbled unto it doing a search under "tendonitis", but here's a question and a suggestion:
Take your shirt off. Put your arms out in front of you, as they would be positioned midway through a REVERSE preacher or standing curl (your palms facing toward the floor). Without moving your forearms (curling motion) watch your biceps as you simply turn your hands so that your palms are facing upwards toward your face......... what happened to your biceps? They contracted and THICKENED! Repeat the demonstration with one arm, and feel it contract with your free hand.
Actually, it was the smaller outer head of your biceps that contracted. The function of the outer head is to twist the forearms as I've just described. We all know that doing "full range of motion" exercises are the best means to create hypertrophy in all our other muscles, yet as you've just now demonstrated to yourself, conventional curls don't provide full range of motion training to the outer head of our biceps. And since we all ESPECIALLY want bigger, more muscular arms, we should then be including an exercise (at least from time to time) to more fully develop the outer head of the biceps, even if it is smaller than the inside head.
BTW, this is not my discovery, I first read about this movement back in the 70's-80's in an article about Frank Zane. Frank developed a machine with handles that employed this twisting movement in order to work the outer head of his biceps. Since most of us don't have this specialized piece of equipment, what else can we do then with our own basic equipment?
One thing I like to do is concentrated curls using an adjustable dumbell and overload the inside "side" (the side closest to the pinky finger as you'd grasp it) with at least 10 or more pounds of weight than you load on the other side. Begin the rep at the bottom in a hammer curl position, meaning your thumb is closer to your face, your pinky closer to the floor. As you contract the biceps and raise the weight, slowly twist your forearm so that your pinky finger is now closer to your face than your thumb as you reach full peak contraction. Hold for a second or two at the top, then twist back on the way down so you end in the hammer curl position you began with at the bottom. As you'll soon FEEL, overloading 1 side of the dumbell makes it more difficult to twist as you lift, and so allows you to work the outside head much more effectively than standard concentrated curls do.
While we're all taught "not to twist and turn" as we do various exercises for safety reasons, this is an exception to that general rule. Obviously, strict form with controlled movement should be used here with no jerking of the weight. And this exercise would be done AFTER doing a primary exercise like standing barbell/ez curls. Yet this twisting motion IS the function of the outer head of the biceps, and without any twisting movement, we're not training that muscle as effectively due to the limited range of motion conventional curls give that head.
This is not to say that I disagree with all the above advice, because overall hypertrophy DOES create both length and thickness, and most experienced lifters agree that standing barbell (or ez) curls is the best overall single exercise for biceps. I agree.
But this is a good supplemental exercise we can and SHOULD work into our routines from time to time to specifically focus on the outer head of the biceps, and will help create an overall "thicker" looking biceps muscle....... and who among us doesn't WANT THAT?
Be well