According to tortora (2000)"Maximal oxygen uptake can be defined as the maximal amount of oxygen
that can be taken in, transported and consumed by the working muscles during maximal exercise. Those who are more fit have higher VO2 max values and can exercise more intensely than those who are not as well conditioned". (p211)
When exercise commences the uptake of oxygen rises rapidly during the first few minutes of exercise. If you are doing steady-rate exercise with minimal lactic acid accumulation, your oxygen uptake reaches a plateau after three or four minutes. If your workout gets progressively harder, your oxygen uptake rises in direct proportion to the severity of the exercise. At some point, the oxygen uptake plateaus with no further increase, even though the workload is still growing. This point is called the maximal oxygen uptake or Max VO2. Additional exercise above Max VO2 generally produces lactic acid, resulting in a deterioration of the performance.
A number of factors affect Max VO2 including the type of exercise, heredity, body composition, gender and age:
Type of Exercise: the type of exercise must be considered when measuring Max VO2. With training, aerobic capacity increases, on average, 6-20%.
Heredity: A series of studies conducted in the late 1960s and 1970s have found out that twins have similar Vo2 max values, whereas the variability for ferternal twins is much greater. These studies proved that having a genetic link can cause a person to have a similar vo2 max value.
Body composition: an estimated 69% of the differences in vo2max scores among individuals can be explained by variation in body mass.
Age: with normal aging, maximal oxygen uptake declines approximately 8% to 10% per decade after 30. The age related decline has also been associated with a decrease in maximal heart...