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 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.

In untrained young women, resistance training that focuses on the beginning part of the movement causes more muscle growth in the lower part of the biceps compared to training that focuses on the end part of the movement.

Your bicep doesn’t work harder or softer when you turn your hand palm-up, palm-down, or straight ahead — it just keeps doing the same amount of work.

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.

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.