Why is it that when performing barbell preacher curls or barbell standing curls, I get a "shin splint" type pain in my forearm?
You’re not alone! This injury is quite common among strict hypertrophy driven lifters! This type of pain usually occurs when both hands are fixed to a bar or a traditional machine, and the participant is restricting shoulder motion in order to isolate elbow flexion/extension. This symmetrical type training does not blend with the asymmetry of upper extremity movement that commonly exists! When was the last time you witnessed a perfect – shoulders fixed / body rigid / right and left- handed elbow curl? It rarely happens!
To grasp a clear understanding one must briefly delve into anatomy (don’t worry it will be quick, ending with a solution to your problem). The elbow is a structurally stable hinge joint. The strong structural stability of the joint is derived from both the bones and ligaments. The elbow permits flexion (curling the weight up) and extension (lowering the weight down). The line through the center of the trochlea and the capitulum (figure 1) represents the axis (center about which we rotate) for flexion and extension.
Why is that important?
The trochlea extends more distal than the capitulum (figure 1). Therefore, the axis for flexion and extension (the motion of the curl) is not fully perpendicular to the shaft of the humerus.
Why is that important?
When you supinate the forearm (figure 2) to grab a bar or a fixed grip handle, commonly seen on many traditional arm machines, the forearm deviates laterally in relation to the humerus, which accounts for the anatomical carry angle.
If the anatomical carry angle (figure 2) is not taken into consideration when curling in isolation, you will most likely experience a negative insult to the area. It is important to note: research has shown differences in the degrees of angle amongst individuals. Therefore, not all weightlifters will experience the same degree of stress.
Solution: Obey your carry angle! Supinate your hands (turn your palms away from your body as in figure 2) and note the lateral angle. This is your individual carry angle. Any time you train with your hands fixed to a bar or a fixed machine you must follow your anatomical angle! If this adjustment doesn’t help, stay away from right/left handed isolated curls. Training with cables or dumbbells allow for right/left handed independency; therefore, obeying an individual’s carry-angle by enabling the forearm to adjust during an exercise. Good Luck!
Figure 1: Anatomy
Figure 2: Carry Angle