Hemoconcentration during isotonic handgrip exercise.

Three healthy males performed an intense isotonic handgrip ergometer exercise to exhaustion (approximately 10 min). Serum water, serum total protein (STP), and hematocrit were determined in the venous blood taken from the brachial veins in both exercised and nonexercised arms before exercise and 10 s, 1, 2, and 3 min after the termination of exercise. Although no sweat was observed, hemoconcentration occurred in both arms. The peak degree of water loss in the nonexercised arm, however, was delayed and lower than that in the exercised arm. Further, three healthy males were exposed to a sauna (76 degrees C) for 20 min to test the effect of sweating on hemoconcentration in the absence of physical movement. Venous blood was withdrawn from the forearm vein before the sauna, after 5 min in the sauna, and at 3 and 30 min during sitting recovery period. No hemoconcentration was observed during the course of the experiment.