Low back pain and leg tingling at gym?

See a Doc: The first thing to do is to try to determine what activity brought about these symptoms. You really need to think hard about this. If you can identify what brought it about, then it may be helpful to speak to a personal trainer to see if you are using poor technique or if there is an activity that you are "overdoing". If the symptoms persist, probably best to see your doc or a back specialist.

Sciatica: Sounds like possibly sciatica. Seek treatment from pcp, orthopod or neurology. Can often be treated with therapy.