Top level endurance running performance requires :

* high VO2max

* ability to sustain a high percentage of VO2 max (fractional utilisation of VO2 max = ml O2/kg/km)

* excellent running economy

Running economy is improved by minimising body weight and particularly by lowering muscle mass below the centre of gravity (thin calves and light weight shoes). It is also a factor of stride length and rate. As speed increases towards the extreme of the human ER range additional speed requires an ever higher cadence.

Endurance exercise is also an excellent countermeasure for aging.

* minimises development of insulin-resistance

* ameliorates age-related mitochondrial dysfunction

* increases mitochondrial SIRT3

These are pathways common to the effects of calorie restriction.