For beginners, lifting weights with one arm or both arms at the same time results in similar biceps growth, indicating that the total amount of weight lifted and number of repetitions matter more...
Mechanism
Synthesis from 1 study
Your muscles grow when they’re pulled hard enough during exercise, no matter if you use one arm or two. What matters is the total weight you lift and how many times you do it—your body doesn’t care which arm is doing the work, just how much work is being done overall.
Most probable mechanism
When you lift weights, the tension on your muscle fibers tells the cells to start building more muscle protein. It doesn’t matter if you use one arm or two—what matters is how much total weight you lift and how many times you do it. More tension means more signals to grow, no matter how you distribute the load across your arms.
Mechanical tension from resistance exercise activates mechanosensitive pathways in muscle fibers, triggering intracellular signaling cascades that upregulate protein synthesis.
When total mechanical load and training volume are matched between unilateral and bilateral protocols, the magnitude of mechanosensitive signaling and downstream mTOR activation is similar.
Increased protein synthesis leads to net muscle protein accretion, resulting in hypertrophy that is proportional to total load rather than limb configuration.
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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