🚫SHOULDER TRAINING MISTAKE!
🚨 Since the scapula must rotate to make room for the head of the humerus a weak lower traps can result in a less stable upward rotation of the scapula. This means deltoid which needs a stable surface to pull from will have a decreased force production and activation.
👇 Another factor is uncontrolled form, this can cause us to shrug the weight using our upper traps to force the weight up which is often the case when the lower traps are weaker. This becomes a problem when trying to use a heavier load, since the deltoid has a very small moment arm compared to that of the weight.
Why should you be using lighter weight for your side delts? Since the weight has a greater moment arm or leverage over the muscle, it must produce a much greater force to move it. For example let’s say you’re lifting a 10kg dumbbell, that equates to 98Nm, and about 49Nm of torque at the shoulder at a distance of.5m. The muscles moment arm is .15m this means the muscle has to generate 326 Nm of torque to hold that weight stationary. Big difference compared to the original 49Nm.
Because of this inefficiency when we try to do a heavier weight we overcompensate with secondary muscles instead of using the deltoid. We can ameliorate this disadvantage by flexing the elbow to an extent to decrease the leverage of the weight. Also remember to keep the scapula stabilized and depressed. Putting the arm in the scapular plane which is slightly forward ~30 degrees can make it more comfortable for your shoulder joint.