I am happy to see more people are aware of the importance of working on stability muscles. If you understand what to avoid and how they should be instead, you may be working more effectively!!
Resisting weight from what Direction
You should know what direction the weight comes from.
Any muscle you train, resist weight (force) to gain that muscle and the force should be the opposite direction for the optimal result. In other words, if the force is coming from different directions, you may not be working effectively.
Bicep curl for example
Make it simple to grasp the concept, when you do biceps curl with a dumbbell, you lift it up towards the ceiling. This works perfectly because the dumbbell naturally drops down to the ground if you keep your hand off from the dumbbell. (Pullups, pushups are great examples, too)
Working Shoulder External Eotator effectively?
I see this quite often at gyms unfortunately. Think about biceps curl example! This is not the optimal way to train your shoulder external rotator at all.
Rotating too much
This is other common mistake. Stand up straight and try shoulder external movement without any weight. You will know immediately how far your shoulder can move externally. With this picture example, the first your shoulder moves externally, reach the limit of range of motion, then the other part of body start moves which is the spine.
Using weight that is too heavy
Lastly, using weight too heavy for training shoulder external rotator muscles make no sense. This is the “stability muscles”. It should be endurance type of training that is with light weight and high repetition. In fact, these muscles are not capable of dealing with heavy weight. Range between 2 – 5lb or resistance band would be good enough.
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how to train Shoulder External Rotator muscle