Astrand, I., Astrand, P-O., Christensen, E. H., & Hedman, R. (1960). Intermittent muscular work. Acta Physiologica Scandinavica, 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 s performed a total amount of 64,800 kpm in one hour on a bicycle ergometer by intermittent work with 0.5, 1, 2, or 3-minute periods of work and rest. Total O2 intake, total pulmonary ventilation, total number of heart beats and blood lactic acid concentration during the work hour and during recovery were determined. It was found that the heavy work when split into short periods of work and rest (0.5 or 1-minute duration) was transformed to a submaximal load on circulation and respiration and was well tolerated during one hour. With longer periods (of two or three minutes duration) the work output approached the upper limit of performance and could be fulfilled only with the utmost strain. In order to explain the low lactic acid values during the short periods of work and rest it was proposed that the myohemoglobin has an important function as an oxygen store during short spells of heavy muscular work.

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