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

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ASTRAND, I., P.-0. ASTRAND, E. H. CHRISTENSEN and R. HEDMAN.Myohemoglobin as an oxygen-store in man. Acta physiol. scand. 1960. 48. 454-460. -The aim of the present research was to investigate further the possible r81e of myohemoglobin as an oxygen-store during the initial stage of muscular work. One subject worked intermittently with a work load of 2,520 kpm/min with varied duration of work and rest pauses on a bicycle ergometer. A highly significant difference in the blood lactic acid concentration during the experimental time of 30 min was found, at work with short work periods (10 sec, lactic acid concentration about 10-20 mg per 100 ml) compared with relative long ones (60 sec, lactic acid concentration 1 10-140 mg per 100 ml). The conclusion was drawn that the first type of work is performed aerobically. The calculated oxygen demand, during the work period of 10 sec, however, does not correspond to the measured oxygen intake. A deficit of about 0.43 1 0, for each period of work will occur. It was suggested that this amount of 0.43 1 0 , is supplied to the working muscle mainlyfrom oxymyohemoglobin. This store function of myohemoglobin is discussed in relation to the present findings and to the results mentioned in the literature.

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