In untrained young women, lifting weights with one arm at a time does not lead to greater increases in overall strength when using both arms together than lifting with both arms at the same time....
Mechanism
Synthesis from 1 study
Training one arm doesn't make your other arm stronger when you use both together, because your brain doesn't learn to use both arms as a team just from working one at a time. If you want to get stronger using both arms, you need to train them together.
Most probable mechanism
When you train one arm at a time, the brain doesn't learn to coordinate both arms together better, so your strength when using both arms doesn't improve more than if you trained both arms at the same time.
Unilateral training induces neural adaptations localized to the motor cortex and spinal circuits controlling the trained limb, without significant cross-activation of the contralateral motor pathways.
Bilateral strength expression requires coordinated activation of motor units in both limbs simultaneously, which is not enhanced by unilateral training due to insufficient interhemispheric communication or bilateral motor learning.
Evidence from Studies
Supporting (1)
Community contributions welcome
Small muscle mass exercise enhances muscular adaptations? Effects of unilateral and bilateral biceps curl on maximum strength and muscle size changes.
Contradicting (0)
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