Lower back pain and free weight/abs workout

Options
I do three strength training sessions a week that are a combination of free weights and ab exercises. This is the second week in a row that I’m experiencing back pain afterwards and it’s really cutting into my workout time (and general mobility)! I’m mostly doing standing tricep, bicep, and deltoid work, as well as standing oblique work. Any ideas what I’m doing wrong, or advice on what to try instead? I thought the ab work would stabilize my core, but I’m concerned that I’m not doing the best ab work for that goal. I’m up for pretty much anything I can try in my home gym.

Replies