Abstract

This study was undertaken to investigate whether part of the ammonia formed during muscular exercise was excreted with the sweat. Male medical students volunteered for the experiment. They exercised 30 min on a bicycle ergometer at 80 and 40 of the predetermined VO2max. Exercise at 80 VO2max was performed twice, at room temperature (20 deg C) and in a cold room (0 deg C), whereas exercise at 40 was performed only at room temperature. Blood was collected from the antecubital vein immediately before and after exercise. Sweat was collected from the hypogastric region by use of gauze pads. It was shown that the plasma ammonia level was elevated after exercise at 80 VO2max and remained stable after exercise at 40 VO2max. The volume of sweat produced during exercise at 80 VO2max at 20 deg C was 428+/-138 ml and at 0 deg C 245+/-86 ml and during exercise at 40 VO2max was 183+/-69 ml. The ammonia concentration in the sweat after exercise at 80 VO2max at 20 deg C was 7,140 micro-mol/l and at 0 deg C 11,816 micro-mol/l. After exercise at 40 VO2max, it was 2,076 micro-mol/l. The total ammonia lost through the sweat during exercise at 80 VO2max was similar at both temperatures, despite the difference in the sweat volume (at 20 deg C, 3,360+/-2,080 micro-mol/l; at 0 deg C, 3,310+/-1,250 micro-mol). During exercise at 40 VO2max, it was 350+/-230 micro-mol. These results show that part of ammonia formed during exercise is lost with sweat. The amount lost increases with increased work rate and the plasma ammonia concentration. Verf.-Ref.