If you use the same weight and do the same number of reps, it doesn't matter if you curl with your arm in front or behind you — what matters is just doing it consistently and getting stronger over...

If you do the same amount of work with your arm in front or behind you, you'll get just as strong at lifting heavy weights — the position doesn't matter.

When untrained adults want bigger biceps, doing simple curl exercises works better than doing rows that use multiple muscles at once.

If you do cable curls the same way every time except for where your shoulders are, it doesn’t really matter for building arm muscle—even if you can lift heavier when your arms are stretched out.

If you're already strong and you train your arms using only the part of the movement where your muscles are stretched (like holding the bottom of a bicep curl), you'll build just as much arm muscle as if you did the full movement — the stretch alone seems to be all you need.

When people want to build bigger biceps, they should focus on bicep curls rather than compound movements like pull-ups that work multiple muscle groups at once.