Nine 56–68-year-old male subjects performed muscular work up to maximal loads on a bicycle ergometer while breathing both ambient air and oxygen. Heart rate increased to an average maximum of 163/min. The maximal O2 intake averaged 2.24 l/min. and the blood lactic acid concentration 85 mg/100 ml. In no case was the maximal heart rate higher when breathing O2 than when breathing air. This low maximal heart rate in older people probably limits the capacity for O2 intake. Four subjects were able to work for about 1 hour without any sign of exhaustion on a work load requiring an O2 consumption of about 50% of their maximal aerobic work capacity. Submitted on October 3, 1958
ASTRAND, I., P.-0. ASTRAND, E. H. CHRISTENSEN and R. HEDMAK. Intermittent muscular work. Acta physiol. scand. 1960. 48. 448-453. -The physiological effect of rest pauses on a non-steady state work (2,160 kpm/min) was studied. A physically well trained subject performed in one hour a total amount of 64,800 kpm on a bicycle ergometer by intermittent work with 0.5, 1, 2 or 3 min periods of work and rest. Total 0, intake, total pulmonary ventilation, total number of heart beats and blood lactic acid concentration during the work hour and during recovery were determined. I t was found that the heavy work when split into short periods of work and rest (of 0.5 or 1 min duration) was transformed to a submaximal load on circulation and respiration and was well tolerated during one hour. With longer periods (of 2 or
Exposure to white spirit I. Concentration in alveolar air and blood during rest and exercise ASTRAND, 1., KILBOM, A. and 6VRUM, P. Exposul'l'O to white spirit: T. Concentration in alveolar ail' and blood during rest and exercise. Scand. j. wOTk enviTon. & hea~th 1 (1975) 15-30. Fifteen healthy male subjects were exposed to 1,250 and 2,500 mg/mil of white spirit in inspiratory air during rest and excercise on a bicycle ergometer. The white spirit contained approximately 83 0J0 aliphatic and 17 % aromatic components. The duration of each exposure period was 30 minutes. The pulmonary ventilation, the cardiac output, and the concentration of white spirit (subdivided into aromatic and aliphatic components) in alveolar air, arterial blood, and venous blood were determined during and after exposure. The concentration of aliphatic and aromatic components in alveolar air tended to level off towards the close of each period. The resting level of the aromatic components increased approximately 2.0 times, and that of aliphatic components about 2.5 times, during exercise with increased intensities. The concentration of aliphatic components in arterial and venous blood increased at the start of each expOSure period but tended to level off towards the close of the period. The resting value increased fourfold in work at the highest intensity. However, the concentration of aromatic components rose sharply during each period. The arterial blood concentration was about 15 times higher at the end of exposure during the heaviest exercise intensity than at rest. Pulmonary ventilation appeared to be more important to uptake in arterial blood than to circulation. The results are believed to be due to the differing solubilities of aliphatic and aromatic components in blood. Measurement of the concentration of white spirit in venous or arterial capillary blood is suggested as a biological check on exposure.
WIGAEUS E, HOLM S, ASTRAND 1. Exposure to acetone: Uptake and elimination in man. Scand j work environ health 7 (1981) 84-94. Eight male subjects were exposed to ·a<:'etone vapor on two occasions for 2:h d.n lIhe laboratory. On the jjirst iOccasion t'hey wer,e ,exposed Ito about 1,300 mg/m 3 dumng r,est a'nd on the second occals'ion to about 700 mg/m 3 during rest (30 min) and eX8l'cise at dJifferent work ]oads on a bicycle ergometer (90 min). The total uptake of acetone was 0.6-1.2 g, 'and the r,elative uptake was ,about 45 0/0. The concentration of acetone in alveol,ar air was 30-40 % of tihat in ,the 'inspiratory air, and rl.t was not affected by exposure time or work 1oad. The concentration of acetone in blood increased continuously wli.t'h inc,reased uptake during exposure, and ,there was no 'tendency towarolS equili'briurn. 'I'he half-time of acetone in alveolar air as about 4 h, and in venous and arterial blood it was about 6 and 4 h, respectively. The 'h~ighest conceIllwatiions of acetone in urine were measur,ed 3-3.5 h after exposure. The ,e)jminat~on of acetone v,ia the lungs corresponded to about 20 % of the Itotal uptake. Only about 1 % of 'the uplta'ke was excreted via ur.ine.
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