Performing your exercises through a full range of motion is supposed to be how you place the maximum amount of tension on the muscles that are working in that exercise. That is not true, however, in some instances, the continuation of a joint’s full range of motion actually takes all of the tension off of the very muscle you are trying to work and grow.
For instance, with the triceps kickback with dumbbells on an inverted bench, how many times do you see someone lift the dumbbells at the top of the movement almost into a curl. What exactly is, this part of the exercise doing for your triceps besides letting them rest while you actively contract the biceps. In order to perform this exercise correctly, the “full range of motion” is actually half of the full range of the elbow.
Think about it. The elbow is capable of flexing and extending. You can bend your elbow until your wrist touches your shoulders or you can extend it until it is straight and in line with the upper arm. Of course, you can stop at any range in the middle of that path as well. That said, just because the full range of motion of the elbow is that it doesn’t mean that a triceps kickback should emulate that.
For the kickback to be effective, you have to use just half of the range of the elbow in order to keep maximum tension on the triceps. In this case, you would stop with the dumbbell pointed towards the ground and the elbow perpendicular to the floor. Squeeze up to the top by extending your elbow fully and come back down again to the halfway point. Full range here would be half the range of the elbow.
In this video, Jeff from Athlean-X YouTube channel teaches you how the advice alone could be costing you some serious gains and how you need to clarify the difference between a joint’s range of motion and an exercise’s range of motion in order to understand it properly.
It goes beyond this however and can be said about the shoulder press with dumbbells. When the purpose of the press is hypertrophy you want to maximize the tension on the delts and not the triceps or assistance muscles of the press. So in order to accomplish this, you want to stop the dumbbells when the upper arms are parallel to the floor and press up from there. Keep your press short and you will dramatically improve the results you see in your delts while performing what is the full range of motion for the exercise.
Lastly, the side lateral raise is another that you want to keep the dumbbells slightly away from your sides when you perform them. On the other hand, if you use cables instead of dumbbells you can let the arm go across your body and you still have tension on the muscles of the shoulders.
The key is understanding that full range of motion is only pertinent to an exercise and not the joint involved in the exercise.