oxygen consumption 怎么等于 metabolic rate了

The actual work performed by the respiratory muscles is very small in the healthy resting subject. Under these circumstances the oxygen consumption of the respiratory muscles is approximately 3 mL.min-1, or less than 2% of the metabolic rate. Furthermore, the efficiency of the respiratory muscles is only about 10%. The efficiency is further reduced in many forms of respiratory disease, certain deformities, pregnancy and when the minute volume is increased (Fig. 5.8). When maximal ventilation is approached, the efficiency falls to such a low level that additional oxygen made available by further increases in ventilation will be entirely consumed by the respiratory muscles.

健康静息受试者呼吸功实际非常小，呼吸肌的氧耗常约为3 ml/分钟，不到2%代谢率的氧耗。此外，呼吸肌的效能只有10%左右。在呼吸系统疾病、某些畸形、妊娠和分通气量增加等许多情况下，呼吸肌的效能将进一步降低（图5.8）。当接近最大通气量时，呼吸肌的效能将极度下降以致于进一步增加通气量而获得的额外氧将完全被呼吸肌消耗。

oxygen consumption 怎么等于 metabolic rate了？是不是要把“氧耗”补上去？