The curls is so popular because many young men have the "Curls for girls" mentality. They think that building big biceps will make them look strong and attractive, and they think that curls will achieve this goal.
I won't debate the "big biceps" point. If you think that huge biceps and teensy weensy shoulders, chest, legs and back make you look great, then go for it. However, curls are not the best way to build biceps.
Why aren't curls the best bicep builders, you ask? Because they don't stimulate the bicep through its entire range of motion, they don't use heavy loads and they don't use the bicep in a functional way.
Range of Motion
The curl involves holding a weight your hands with your arms extended straight down, and then moving your forearm up until the weight comes to your shoulders. In a curl, the elbow is moved through the entire range of motion and the shoulder moves very little. This movement does not use the bicep to the fullest possible extent, since the bicep is involved in both elbow flexion and shoulder flexion (shoulder flexion is when you move your upper arm upwards and in front of you). For an exercise to work the bicep through its full range of motion, it should involve movement around both the elbow and the shoulder.
Most people can't handle much weight on curls. Even if someone does curl a lot of weight, that amount of weight is much less than that person could handle on other exercises that work the biceps. (see the list below!) In strength training, more weight lifted = more muscle built, so if we are to stimulate bicep growth, we need to use exercises with which we can use the biceps to move heavy loads.
The curl is also not a very functional exercise. A functional exercise is an exercise that is very similar to a real-life movement and helps to strengthen and/or improve that movement. Functional movements are the most useful for adding on muscle mass and strength. Deadlifting, for example, is an awful lot like picking up something heavy off of the ground. Outside of the gym, however, you will hardly ever perform a curling motion.
So, what are some bicep exercises that work the bicep through its entire range of motion, use heavy loads and are functional? I'm glad you asked!
Grab a pullup bar or other sturdy overhead support with a supine grip (palms towards you). Pull yourself up until your chin is above the bar. Lower yourself until your arms are completely straight. Repeat.
With a chinup, you're using the bicep to flex both the elbow and the shoulder, you're moving your bodyweight (or more, if you add weights!), and your arms are doing exactly what they'd do if you had to climb up or over something.
Bent Over Barbell Row
Keeping your back straight and your knees slightly flexed, bend over at the waist and grab the bar on the floor in front of you. Grab the bar in an overhand grip and pull it straight up towards your Xiphoid Process (that spot right above your abs, at the bottom of the sternum).
Once again, you're moving both the elbow and shoulder joints, you're using a load much heavier than you would curl, and you're performing an action that looks a lot like picking something up off of the ground.
There are a couple of other exercises that are also very helpful in building the biceps, even though they don't involve all 3 aspects mentioned above (full range of motion, heavy loads, functionality):
With a bar at mid-shin level, place your feet slightly narrower than shoulder width apart with the middle of the foot directly under the bar. Keeping your back straight, bend at the knees and hips to grab the bar. Your shoulder blades should be directly over the bar and your back straight. Extend your knees until the bar is above them, and then extend at the hips until you are standing completely upright.
This exercise doesn't involve any movement around the elbows and very little around the shoulders, but it works your biceps isometrically under an extremely heavy load. And exercises don't get any more functional than a good heavy Deadlift.
Hold a bar on your front shoulder and chest, with your chest up and your elbows slightly in front of the bar. Press the bar directly over your head until your arms are fully extended, then return the bar to the starting position.
Yes, the press hits the triceps much harder than the biceps, but remember that the bicep is involved in shoulder flexion, which occurs rapidly in the early part of the press. Again, weights used on the press are much heavier than weights used for curls, and the Press works specifically on the shoulder flexion use of the biceps, which is usually the least-trained aspect of the bicep.
Sure, if you're big into bodybuilding, you'll need to do a few curls for that "pump." But if curls and curl variations are your only bicep exercises, your "guns" will always be more like Noisy Crickets.
For those of you who don't know what the Noisy Cricket is.
3 x 3 x 240
3 x 3 x 125
3 x 2 x 135
12, 9, 9
Comments: A little stiff from sprints yesterday, especially in the left hamstring. Squats felt a bit tough for a light day -- apparently those suckers are hard no matter what. Did 80% of Push Press weight for strict Press, and it felt about right. I'm starting to really like Power Cleans. Aiming for 12, 10, 9 on Pullups next week.