Hi, as you can guess, my question is; how can I increase my arm width? I've been working out for the last 4 months and the only time I saw an increase in my upper arm width with was during my first month. After that, it kind of stopped or diminished. My forearm width is cool, my arms seem to get bigger towards front and back continuously and I'm getting nice curve on my shoulders too but my upper arm width stays the same. Is there a way to target whichever "head" that contributes to width(in biceps and triceps) or is it just harder or late to grow?

FYI; 67 kg weight, around 15 percent Body fat, 1.78 cm(5'10) height.

Biceps workout;

Alternate Dumbbell Curls 3x10

Hammer Curls 3x10

Scot Curls(Machine) 3x10

Triceps workout;

Dumbbell Overhead Triceps Extension 3x10

Bench Dips 3x12

One Arm Dumbbell Triceps Extension 3x10

Your bicep has 2 heads the long head (outside of bicep) and short head (inner part of biceps). The Brachialis is a less prominent muscle beneath the main bicep. No matter what exercise you will always hit your whole bicep but you can choose exercises to put more emphesis on a specific head. For example: Incline DB Curl with your elbows behind your waist will hit your long head more, Preacher Curls with elbows in front of your waist hit your short head more and Hammer Curls with your elbows next to your waist will hit more Brachialis.

Same on your Tris. You have your Long Head which is the inner part of your Tris and would be any exercise with your elbows above your head or out in front of you. Your Lateral Head which would be your outter part uses any exercise with elbows down at your waist. Your medial head would be the deep center of your tri and to be honest pretty much any exercise that hits the long head will hit the medial equally like dips, close grip bench and skull crushers.

Utilize all angles for bis and tris and you will see the size all around. Also yes, arms are hard for some people to grow especially the bis so be carefull not to overtrain them, that's the problem for most.

Good info from Aaron.

And just to add a little bit more, you've only been working out for 4 months. Just keep training longer and you will see growth over time. I'd also swap out the bench dips for dips on a bar.

I train my bis with my chest, rest one day, then train my tris with my shoulders. I feel the soreness on my muscless for at least two days after though my soreness after bicep training is always on the insides of my elbows rather thanmy humble peaks. My training sessions are around 90 minutes because I complete my reps pretty slowly and do a 4 excercise ab workout on both days. If my other exercises aren't taking too much toll on my bis and tris, I guess I'm not overtraining them.

Yeah, I know I'm pretty new, but I still felt the to need ask this because proportions seem a bit off. My arm size is slowly increasing to front and back but not to the sides ever since I entered my second month in traning. I face the mirror and contract my upper arms; my arm size is funny, I turn to one side a bit and my arms kinda look pretty nice for my standards. Insides of my arms seems to get dented(don't know if I used the right word, english isn't my main language) when I contract them.

Just keep training. Make sure you are targetting both heads of the biceps and all three heads of the triceps. Train for a year or two before you start looking at what muscle group is lagging.