Employee reported at 11:30, ee bent over to pick up a 14"" pipe wrench. When ee straightened up, ee had some back pain. Employee stated that ee had a pre-existing back pain issue (that was NOT work related) and this may have aggravated it. Employee was taken to medical provider, examined, and placed on restricted duty (no lift, push, pull>10 lbs) until re-evaluation (4 days)