Doing the same movement with your arms either with one barbell in both your hands or one dumbell in each hand you will be able to lift more weight using the barbell. And the difference being the piece of metal that connects your hands and stops them from moving closer or further from each other, the barbell in other words.
If the muscles that would move the hands away from each other were completly balanced with the muscles that moved the hands closer together there would be no benefit of the barbell. There would be no tear of the barbell and no compressing of the barbell. And it would be as if you were lifting to dumbells holding your hands at an exact distance from each other.
Obviously this isnt the case in most movement patterns, and in a benchpressing situation most people lift significantly more when using a barbell.
Anyway to me this means that using barbells or machines to remove degrees of freedom when pusing or pulling weight can increase power output by either increasing the tension in a agonist stabilizer or decreasing tension in a antagonist stabilizer.
This makes me believe that the more degrees of freedom an exercise has the more balanced in strength will your stabilizers have to be to deliver optimal performance in a lift. That means training that require a lot of balance will train stabilizer to be balanced.
Hopefully a secondary effect of this balance of stabilizer strength will be that you can train more effectivly and gain more muscle.
Is there something I am overlooking coming to this conclusion, what would that be?