The time it takes for oxygen delivery to respond to the demands
of exercise is called "V02 kinetics". The diagram below shows
what happens when we start running from an initial standstill
without any Warmup. The red line represents our exercise level
as oxygen consumption, and it rises rapidly to a steady-state
that represents the demands of the running pace. The blue line
on the other hand represents the rate of oxygen delivery which
is mostly controlled by breathing and heart rate. As you can see
the oxygen delivery lags behind the oxygen consumption and this
creates an oxygen debt represented by the yellow area. This
oxygen debt does not cause a drop in the oxygen saturation of
our blood (hypoxia), but rather forces our body to produce
energy anaerobically (literally without oxygen). Our body will
attempt to repay this oxygen debt by providing more oxygen as
shown in the green area. The imbalance caused by the oxygen debt
and the anaerobic energy production can actually last for
protracted time and results