You might’ve already noticed that as you curl a weight up, it gets harder and harder and becomes the most difficult mid-way when your forearm is perpendicular to the ground.
After this point, it gets easier.
Your body can sense this and finds ways for you to “cheat” through this difficult bottom half of the movement without you even realizing it.
One way it does that is by initiating each rep with a slight swing.
I’m sure we’ve all seen guys at the gym who take this to the extreme, but even just a slight swing at the bottom can make bicep curls (no matter your preferred variations — including dumbbell bicep curl or cable bicep curl) feel much easier and enable you to use heavier weights.
The problem with that, however, is although you’re able to use heavier weight, it doesn’t result in more tension to your biceps. That additional load goes straight to your lower back which is now helping you get the weight up by using momentum.
And ... that is probably why you've been feeling that nagging ache in the lower back. For quick relief,
For the next mistake, I want you to take a look at two really interesting studies.
published just last year had subjects perform the preacher curl but under two different conditions.
One group performed only the bottom half of the curl and the other group performed only the top half of the curl, using a weight that matched their strength level in each position.
The biceps of each subject was measured at three points.
After 5 weeks, here’s what happened.
The group that performed only the bottom half experienced roughly 2.6 times more biceps growth when averaged across the measurement sites. However, what’s interesting is that most of this growth occurred at the third measurement site, located towards the bottom of the bicep.
I remember for the longest time, whenever I’d do bicep curls (be it bicep curls with dumbbells or with cables) I’d end up feeling it more in my forearms than in my biceps.
In some cases I’d have to stop my sets not because my biceps failed but because my forearms just couldn’t handle holding the weight any longer.
The reason for this had to do with my wrist position.
The function of the inside forearm muscles is to flex the wrist. Many people, when they curl, subconsciously flex their wrists when trying to get the weight up. This can lead to the forearms working harder than they have to be, eventually leading to fatigue and cramping.
Next, let’s talk about the elbows.
The primary function of the biceps is to flex the elbow. But whenever you curl with a weight that’s too heavy for your biceps to lift, your front delts will start to help out by swinging your elbow forward.
Now some argue that this elbow-forward movement, called shoulder flexion, is actually beneficial to do when you curl because it’s one of the functions of the biceps.
This is true, but it’s only a secondary function of he biceps.
The front delts are far better at performing this movement. And in fact, tested this and found that allowing the elbows to excessively sway forward during bicep curls led to less biceps activation and more front delts activation. The opposite of what you’d want.
So instead, keep your elbow locked as you perform the bicep curls and focus on the biceps’ primary function: flexing the arm.
If you take a look at my form now you’ll notice I’ve corrected all the common bicep curls mistakes I previously went through.
But there’s another mistake not visible to the eye that can potentially slow your gains.
To explain this, let’s refer to a that some of you might remember from my past articles.
Within it, researchers randomly assigned participants to 2 groups:
Group 1: Told to perform bicep curls while really focusing on squeezing the biceps and really feeling the muscle work Group 2: Instructed to simply lift the weight
