Can you improve arm strength?

I have always wondered if pool training/swimming would improve arm strength. I know some teams do it but I mean if there was a work out regiment designed for QB and baseball players . Anyone remember Kickboxer with Van Dam ? In the water submerged practicing kicks and punches ? Cheesy reference I know but the theory is sound . QB underwater simulating passes or throwing a football sized weighted ball would increase arm strength and speed , working muscles that you normally wouldn’t . I would think an increase in shoulder strength as well . It would in fact totally increase core and leg strength as well if you simulate moving in the pocket too . A weighted belt or ankle weights and an air supply is all you’d need . I think most teams have a pool . To me it makes sense that doing a workout like that a few times a week with the resistance of the water . Would be similar to a boxer taking off 16oz gloves and going to smaller gloves . For all I know they may already do this but haven’t heard of it .