When you do triceps exercises with your arm stretched overhead instead of at your side, your triceps muscle grows more—even if you’re lifting lighter weights.

Overall, your whole triceps muscle grows more when you do the exercise with your arm overhead—even if you’re not lifting as heavy.

Even the smaller parts of your triceps grow more when you do the exercise with your arm overhead instead of at your side.

If you're a young guy who hasn't trained much before, doing exercises that only move your elbow (like lying triceps presses) makes your triceps muscle grow way more than doing exercises like bench presses that use multiple joints at once.

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, 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.