When people who have never trained before start doing resistance exercises - whether they use strict form (slow, controlled movements) or add external momentum (like swinging weights) - both methods make the muscles in their upper arms bigger.

Even though people who swing weights use their whole body more, their upper arms don’t get any thicker than those who lift strictly—so the extra movement doesn’t help build more arm muscle.

After doing bicep curls 24 times over 12 weeks, women’s upper arm muscles got noticeably thicker, no matter which way they did the curls.

If untrained adult men lift weights twice a week for 8 weeks, doing 4-6 sets of 8-12 reps until they can't do any more, their upper arm muscles will get bigger - this is measurable with ultrasound or other imaging.

When young men who haven't trained before do either multi-joint exercises (like curls) or single-joint exercises (like bicep curls) for 10 weeks, their arm muscles grow by about the same amount - there's no meaningful difference between the two types of workouts.

If you're an average gym-goer doing one-arm bicep curls, doing more sets than your usual routine won't make your arm muscles bigger or stronger—your gains plateau at your current volume.