In men who have not previously trained, performing 8 weeks of biceps curls results in more muscle growth in the upper arm than performing dumbbell rows, suggesting that exercises targeting a single...
Mechanism
Synthesis from 1 study
When untrained men do biceps curls, their biceps and brachialis muscles bear all the weight alone, making them work harder and grow more than when they do dumbbell rows, where other muscles help and limit how hard the biceps can work — this is why biceps curls led to nearly double the muscle growth...
Most probable mechanism
When untrained men do biceps curls, the weight pulls only on the biceps and brachialis muscles, making them work harder and get more stressed than when they do dumbbell rows, where other muscles help carry the load — this extra stress triggers more muscle growth, as shown by thicker biceps after 8 weeks of training (10.1519/JSC.0000000000003234).
Single-joint biceps curl exercise applies mechanical load exclusively to the elbow flexors (biceps brachii and brachialis), without requiring significant contribution from other muscle groups to complete the movement, allowing the target muscles to bear the full load (10.1519/JSC.0000000000003234).
This isolated loading enables the elbow flexors to reach full concentric failure under load, maximizing mechanical tension and metabolic stress within the muscle fibers, which is limited in compound movements like dumbbell rows due to premature fatigue of synergist muscles (10.1519/JSC.0000000000003234).
Elevated mechanical tension and metabolic stress activate intracellular signaling pathways, including mTOR and MAPK, which increase the rate of muscle protein synthesis and reduce protein breakdown (10.1519/JSC.0000000000003234).
Sustained activation of these pathways leads to net accretion of myofibrillar proteins, increasing muscle fiber cross-sectional area and measurable muscle thickness in the elbow flexors (10.1519/JSC.0000000000003234).
Evidence from Studies
Supporting (1)
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Single-Joint Exercise Results in Higher Hypertrophy of Elbow Flexors Than Multijoint Exercise
Contradicting (0)
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