0 the extra oxygen that the body uses during exercise, which must be replaced when resting -- 氧债（运动时身体消耗的额外氧气，需要在运动后恢复）
It also moderately increases heart rate and stroke volume (oxygen debt).
In hypovolemic shock for example, approximately 50% of the metabolic acid accumulation is lactic acid, which disappears as blood flow and oxygen debt are corrected.
This contributes to their susceptibility to the oxygen debt mentioned before.
Animals out of water only have about 73% the respiration of submerged animals, and likely incur an oxygen debt while out of water that must be repaid once resubmerged.
