Why do we run VO2 Max Intervals?

You don’t increase your oxygen supply by breathing in more air. You increase it by improving transportation of oxygen to your muscle fibres. While your heart and major blood vessels handle bulk transport of oxygen throughout your body, it’s the very smallest blood vessels, your capillaries, that deliver oxygen to muscle fibres themselves. Capillaries are so small that red blood cells, which carry oxygen, pass through them in single file. The only way to route more oxygen to a muscle fibre is to create more capillaries.

Once delivered, oxygen is used by each muscle fibres mitochondrial power plants to create energy. The only way to increase energy production is to create more and bigger mitochondria.

Bottom line: You need to create more capillaries and bigger, more numerous mitochondria. Otherwise, breathing in more oxygen is like pumping 20 gallons of gas into your car’s 10-gallon tank—lots of spillage, but no increase in available fuel.

It’s not the amount of oxygen you can breathe into your lungs that counts. It’s the amount of oxygen that your mitochondria consume to create energy.

For a VO2max workout to be effective (i.e., to stimulate the creation of lots of capillaries and mitochondria), you’ll need to run repetitions at a minimum of 90 percent of your current VO2max. Less won’t stimulate the improvement you’re after; conversely, working at greater than VO2max will leave you more fatigued without offering an increased benefit.

VO2max reps are best measured in minutes, not distance (e.g., a mile repeat), because it’s the amount of time at near-VO2max that counts, not the distance you travel at that effort.

VO2max repetitions should last a minimum of two minutes (it takes approximately two minutes of running for your aerobic system to reach VO2max), with a maximum length of 6 minutes). The recovery interval should be 2–4 minutes.

Good luck and enjoy tonights set!

Arete Coaching Run Session Tuesday 13th

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