1. If you are only doing bicep curls in your workout you are only benefiting your arms in that workout. Another way to benefit  your health would be a 20 minute warm up jog.  This would get the blood flowing through the muscles before lifting weight and would not only work on arms but also legs and cardio.

2.  If you start using the treadmill for your workout you are targeting your legs and mainly cardio.   Another workout you could do to target other areas of your health would be  to use the stair clumber.  This would mainly target your legs and plus build up stamina and cardio.