Answer:
Oxygen uptake
Oxygen uptake (VO2) is the amount of oxygen that the body takes up and utilizes. This is an outcome used in exercise physiology as it is reflective of the oxygen uptake at the exercising muscle. Oxygen is taken up in the lungs and is carried around the body by the blood until it is released at the exercising tissues. Oxygen uptake can be measured by gas analysis of the oxygen content of inspired air vs. the oxygen content of expired air. During exercise at a constant workload, VO2 increases exponentially at the start of exercise until it reaches the point at which oxygen supply matches oxygen demand and then it plateaus, this plateau is termed steady-state (Figure 1.5).
VENTILATION AND ANIMAL RESPIRATION | The Effect of Exercise on Respiration
H. Thorarensen, in Encyclopedia of Fish Physiology, 2011
Abstract
The O2-consumption rate of fish increases exponentially with swimming velocity. To support the increased metabolic demands of the locomotory muscles, O2 delivery from water to tissues is increased through a series of controlled physiological adjustments including higher ventilation rate, larger area for gas exchange at the gills, higher cardiac output, and greater extraction of O2 from blood at the tissues. Similarly, the delivery of CO2 from muscles to gills is increased in step with the O2 consumption. Although all aspects of the cardiorespiratory system are matched, the primary limitation to maximum O2 consumption in fish appears to be cardiovascular O2 transport.
