Endurance seems to have three main factors that affect your endurance performance - maximal oxygen consumption (VO2 max), lactate threshold and efficiency (oxygen cost to generate a given speed or power).

When VO2 max and lactate threshold are combined this can determine a ‘performance VO2’, the oxygen consumption that can be sustained for a given period of time.

This performance VO2 when combined with efficiency can give the speed or power that is able to be generated at a given oxygen consumption [1].

To maintain a specific work rate or speed energy must be required adenosine triphosphate (ATP) must be supplied as quickly as it is used, the rate at which oxygen is used during exercise is a measure of the rate at which ATP is generated.

Being able to perform at a high speed and maintain it is linked to the ability to maintain a high rate of oxidative ATP production [2].