When people do light weight training with blood flow restriction on their biceps, the muscle grows evenly no matter if they do the exercise with their arm bent a lot or a little — growth looks the same along the whole muscle.

For guys who lift weights, doing arm curls with the arm stretched out doesn’t build more muscle than doing them with the arm bent, even when using light weights and blood flow restriction — at least over 3 weeks.

If you're new to lifting weights and do bicep curls with heavy weights, then wrap your arm tightly after exercising, you might end up with slightly less muscle growth in your upper arm compared to not wrapping it at all.

For young guys who lift weights, squeezing the biceps at the top or bottom of the move doesn’t make a difference in muscle growth when using light weights with blood flow restriction.

Doing bicep curls only halfway up (keeping the arm stretched) might make the lower part of your bicep grow a tiny bit more than doing full curls, but the difference is very small.

Doing light weightlifting with blood flow restriction four times a week for three weeks can make arm muscles grow a little in young, trained guys — about 4% to 8% bigger.