They may not be eating well and they are putting their bodies under undue stress. I used to watch my husband bench-press 300 pounds, with the veins standing out on his temples, and wonder what those little VHL capillaries looked like in his retinas and brain. I don't think doing that kind of exercise is good. Lifting weights is not aerobic. You want something that will increase oxygenation.
Swimming is great, or walking.
He is much more tired since his spinal surgery a year ago. He requires more sleep than he used to, and he got every cold this winter. Normally he never gets sick. He takes a multi-vitamin. He probably needs more Vitamin C than that.