Re: Big arms
How long have you been doing this routine? Do you work your other muscle groups at all? Are you eating enough calories/protein? Are you allowing for enough rest? Are you no longer seeing any muscle growth? At 15, you still have a lot of growth to go through. You should not be so concerned with size just yet. In the next few years you will be growing a lot and if you are weight training, that will help you to put on muscle during that time. If what you're doing has been working, stick with it and focus on strength.
Keep your body lean, your blood clean and your mind sharp. -Rollins