The effect of tiring the forearm muscles in different ways on venous blood pH, pco2 and standard bicarbonate.

1. The changes in venous blood pH, p(CO2) and standard bicarbonate caused by tiring the forearm by (a) rhythmic work with free circulation, (b) rhythmic work with ischaemic circulation, were determined using the Astrup apparatus.2. For rhythmic work, opening and shutting the hand as quickly as possible for 2 min, the averaged results on six subjects were: pH fell 0.19 units; p(CO2) (after full oxygenation of venous blood) rose 52 mm Hg; standard bicarbonate fell 2.9 m-equiv/l.3. For rhythmic work during ischaemia and accompanied by pain, the averaged results on six subjects were: pH fell 0.19 units; p(CO2) (after full oxygenation of venous blood) rose 26 mm Hg; standard bicarbonate fell 6.3 m-equiv/l.4. These results are compared with those obtained in an earlier investigation on the effect of strong hand grips for 1 min.