you might also look into potassium tablets. If he's sweating a lot he's losing potassium. The three things that remove potass from the body are:
sweating
breathing with your mouth open
urination.
Some of the symptoms of potass imbalance are: leg cramps, headaches, muscle fatigue, "heavy legs"
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand, strawberries in the other, body thoroughly used up, totally worn out and screaming: "Yeah Baby! What a Ride!"