A comparison of spirometric values with subjects in standing and sitting positions.

Spirograms obtained from 235 subjects in standing and sitting positions revealed small differences for the forced vital capacity (FVC) and forced expiratory volume in one second (FEV1). No statistically significant differences were found for the mean forced expiratory flow during the middle half of the FVC (FEF25-75%, or maximal midexpiratory flow) and FEV1/FVC. Sitting values were, on the average, higher for determinations greater than FVC of 2.14 L, FEV1 of 1.68 L, FEF25-75% of 2.16 L/sec, and FEV1/FVC of 75.7 percent. On the average, subjects with less than these values performed slightly better in the standing position.