After 8 weeks of doing dumbbell rows, the muscles at the back of the upper arm near the elbow show almost no growth, suggesting that this exercise may not effectively build muscle in those specific areas.

After 8 weeks of training, dumbbell curls lead to a 11% increase in muscle size near the elbow compared to dumbbell rows, which result in only a 1% change, suggesting that exercises involving a single joint may produce greater muscle growth in the distal part of the muscle.

After 8 weeks of weight training, the upper part of the biceps grows more with both dumbbell curls and rows, while the lower part grows more with curls than with rows, indicating that different parts of the muscle respond differently to different exercises.

Your bicep doesn't grow more at the top, middle, or bottom no matter how you do the curl — it grows evenly all along its length.

In untrained young women, performing bicep exercises using only the first half of the movement range for eight weeks leads to more muscle growth in the lower part of the biceps and greater strength gains than using only the second half of the range.

In untrained young women, performing bicep exercises through a shorter range of motion (from fully extended to halfway bent) leads to more muscle growth near the elbow than using a longer range (from halfway bent to fully bent), but both approaches result in similar muscle growth in the middle of the bicep.