Weak Wrists and Lumbar
 

First: Does anyone know of anything I can do to strengthen my wrists and forarms? I have pain when doing push ups, or any exercise that requires my weight be placed on my hands. I've tried using fists instead but I feel like my fingers are swelling up when I do that.

Second: I have a weak lumbar and it's causing pain during crunches and sit-ups. Does anyone know of any exercises I can do to strengthen the lumbar, as well as alternative exercises to strengthen the abs?

Thank You