My dad's blood pressure is usually around 140/90, and he is 52 years old. Since mid-July I've got him working out with me, just a standard 3-day split. He checks his BP before and after every workout. Generally it had been around 120/80 ~10 minutes after lifting, but this past week he had a reading of 90/55. His doc has given him the go ahead to lift, and he's never had any issues with weakness or exhaustion, but this really worried me and he's now going to check with his doctor on this. Have any of you all heard of something like this happening? I am curious to know some possible causes, and it might be a while before he actually gets in to the doc.