[Pulmonary ventilation and oxygen consumption during passive and active motions in man]

Changes in pulmonary ventilation and O2-consumption were studied during passive and active extension of both crura. The rate and extent of the movements were the same (1Hz). Thirty 21-year-old men (mean weight 72.5 kg, mean height 179 cm) were divided into 3 equal groups, namely controls, with passive movement, and with active movement. The trial consisted of three 11-12 minute periods--initial, period of movement, and recovery. In the control group movements were not performed. Passive movements were carried out by means of a special lever. Ventilation increased at active movements (12.42 +/- 2.731 compared to control values of 8.62 +/- 2.87). Oxygen consumption was increased during active movements (8.4 +/- 2.3 ml.kg-1.min-1 compared to 4.4 +/- 0.6), yet it was reduced during passive movements (3.5 ml compared to control values of 4.4 and initial values of 4.3 ml). The finding is accounted for by the rapid depression of the metabolic efficacy of isolated proprioceptive afferentation as a specific feature of conditioned reflex regulation of metabolism in man.