The great endurance coach Arthur Lydiard wrote, “Aerobic training at moderately high volumes is absolutely essential in developing the endurance athlete. Increased numbers of capillaries are produced, resulting in an increased ability for your body to transfer blood gasses and essentially deliver more oxygen faster to working muscles. Your lung capacity improves, both by increasing the amount of air taken in during a single breath and by utilizing more oxygen within each breath due to increase numbers of pulmonary capillaries. The left ventricle of the heart increases in size and stroke volume, meaning the amount of blood pumped per heart beat is increased; hence more oxygen is carried around the body per minute increasing your VO2 Max.”
Simply stated; capillaries let water, oxygen, carbon dioxide, nutrients and waste products pass between your blood and muscles. Having more capillaries means when you’re exercising your muscles can get more oxygen and nutrients, and easily offload waste products and gases. Your VO2 Max is the maximum rate at which your muscles can take oxygen from your bloodstream.
Capillary production at various run durations:
| Time | ||||
| 2.5 hrs | 1 Googol | |||
| 55 min | 10,000 | |||
| 30 min | 100 | |||
| 20 min | 5 |