Triathlete Cornering on Bike Course at Pittsburgh Triathlon

VO2 max is typically achieved in an all-out effort of 3-8 minutes depending on your genetics and fitness. Outstanding athletes may be able to hold their true VO2 max for a full 8 minutes, but most people cannot.

The whole idea of interval work (at any intensity) is to use shorter sets with rests to add up to a total of more work that you would otherwise, be able to do as a continuous effort. You can reach your VO2 max after about 30 seconds of starting an interval at the appropriate intensity, but after you stop or slow down, our oxygen needs diminish and your heart rate slows, and you are no longer at your VO2 max. When you start your next interval, your “bucket” has only partially emptied depending on the intensity of your rest interval (how low your HR or Power or Vo2 drops during the rest)…which determines how far you need to fill the bucket up again to be back at your Vo2 Max.

So if the goal is to get as much work in as possible at VO2 max
efforts, you can see how shorter, more intense rest intervals would
let you reach your VO2 max effort more quickly once you re-start a
given interval.

So if the goal is to get as much work in as possible at VO2 max
efforts, you can see how shorter, more intense rest intervals would
let you reach your VO2 max effort more quickly once you re-start a
given interval.

So the next question is how long should the intervals be?

Tabata intervals (10 sec max, 20 sec rest) will hit a component of VO2
eventually, but they are really best for anaerobic conditioning.
Billat’s intervals (30 at vo2 max-30 at “rest”) are great for an
introduction to VO2 max efforts for either newbies, or early in the
season, with little worry for injury. In addition, her work has shown
that after a 4-6 week block of VO2 interval work, only 2-3 minutes of
VO2 work per week are required to sustain your gains before they drop
off to far. So you can cycle your VO2 work early in the season and
see some benefits, taper them off in the spring time and resume them
prior to or during race season. Of course, if you can tolerate the
longer intervals (2, 3, 5 minutes or more) at your VO2 max power, you
will pack in the most time at VO2 max.

Finally, about what power to do your intervals at…since by
definition, your 5 minute power is going to be close to your VO2 max
effort (and could only be confirmed with expired gas testing in a
lab), you might as well use that 5 minute power as your target power
for your VO2 intervals.

There’s no right or wrong as long as you are applying physiology
appropriately. The most important part is to have a plan to follow
and be able to measure your progress. Ways of measuring your progress
could be to do a block of VO2 intervals for 4-6 weeks as part of your
regular training with a progression that makes sense, and then measure
either your all out 5 min power again, OR hold your 465W and see how
long you can hold it after the training block.

So if the goal is to get as much work in as possible at VO2 max
efforts, you can see how shorter, more intense rest intervals would
let you reach your VO2 max effort more quickly once you re-start a
given interval.

So the next question is how long should the intervals be?

Tabata intervals (10-sec max, 20-sec rest) will hit a component of VO2
eventually, but they are really best for anaerobic conditioning.
Billat’s intervals (30 at vo2 max-30 at “rest”) are great for an
introduction to VO2 max efforts for either newbies, or early in the
season, with little worry for injury. In addition, her work has shown
that after a 4-6 week block of VO2 interval work, only 2-3 minutes of
VO2 work per week are required to sustain your gains before they drop
off to far. So you can cycle your VO2 work early in the season and
see some benefits, taper them off in the springtime and resume them
prior to or during race season. Of course, if you can tolerate the
longer intervals (2, 3, 5 minutes or more) at your VO2 max power, you
will pack in the most time at VO2 max.

Finally, about what power to do your intervals at…since by
definition, your 5-minute power is going to be close to your VO2 max
effort (and could only be confirmed with expired gas testing in a
lab), you might as well use that 5-minute power as your target power
for your VO2 intervals.

There’s no right or wrong as long as you are applying physiology
appropriately. The most important part is to have a plan to follow
and be able to measure your progress. Ways of measuring your progress
could be to do a block of VO2 intervals for 4-6 weeks as part of your
regular training with a progression that makes sense, and then measure
either your all-out 5 min power again OR hold your 465W and see how
long you can hold it after the training block.

I hope that gives you some more ideas on how to design integrate VO2 max sets into your training.

This article originally appeared on my retired blog, exercisephysiologyMD.com in January of 2009

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