The effect of repeated testing on the maximum breathing capacity in normal subjects.

The maximum breathing capacity (M.B.C.) test (Hermannsen, 1933) may be used as an index of the ventilatory function of the. lungs not only on one occasion but also, when the test is repeated at intervals, as an objective assessment of the progress of disease and of the effect of treatment upon it. Although there have been some reports of the effect of repeated testing of the M.B.C. on one day, there appears to have been no study of the influence of learning on the M.B.C. when the test is made at intervals over a period of time. There has been difference of opinion about the effect of learning on the M.B.C. when tested on one occasion. Gray, Barnum, Matheson, and Spies (1950) found an improvement of 12% between the first and second tests, and of 4% between the second and third tests, performed by healthy young people. After this no improvement occurred. Gilson and Hugh-Jones (1949), however, recorded no such improvement of M.B.C. in 17 patients. This paper reports a re-examination of the presence of a learning factor in the acute experiment and an investigation of the effect on the M.B.C. of its repeated performance over a period of time.