How to Perform VO2 Max Intervals Properly with a Power Meter

When I bought my first power meter in 2001, I quickly discovered that intervals are more effectively executed using power rather than heart rate. In this training tip, I will explain how to perform VO2 Max intervals with a power meter, "The Right Way". Utilizing a power meter for intervals provides significantly greater benefits compared to relying on heart rate or perceived effort.

Listen to our podcast about performing VO2 Max Intervals "The Right Way" with your Powermeter 👇

But first, if there is one single thing you can do to become faster, it's VO2 max intervals.  With power data, it is possible to evaluate an athlete's interval 'technique' and show them visually how to perform intervals with a power meter. Even if you don't have a power meter the graphical analysis below will help you conduct your intervals the "RIGHT WAY" by “feel”.

The Right Way:

In the graph below, one can see power, heart rate and elevation data. This is the "RIGHT WAY" to perform intervals with a power meter: consistent steady power output. Notice how the last interval (av 414 watts) is close to the first interval (av 445 watts). We call that proper interval pacing not only during the one interval but for all 4 intervals in the set.

During the interval, use the real time power data to adjust your effort based on your power readout and the prescribed wattage ranges. We like to say, "Not too hard, not too easy, just right like Goldilocks. A steady effort produces a nice consistent power output over the course of the interval as shown above. The bottom line is to go as hard as you can but gauge your effort so that you can finish the interval with as much effort or power as you started the interval. If you can do this your power output will look like the graph above and you are well on your way to improving and maybe winning some races.

The Wrong Way:

Starting off too hard at the beginning of an interval is a common mistake especially for cyclists going off of heart rate alone. Notice how these intervals below start with a huge surge above the prescribed ranges followed by a drop in power below the prescribed range for the remainder of the interval. In other words the athlete “blew up” chasing a heart rate zone and exceeding the prescribed wattage range. Don’t make the mistake of going as hard as you can in order to get your HR up as soon as possible. Heart rate lags behind your power output and in the case of these intervals is not a true indicator of what’s going on.

Use the upper end of your wattage zones to not go too hard and use the lower end to stay above and not go too easy.  The Zone 5 VO2 Max range below is 306 - 362 watts. 

Therefore, when doing VO2 Max intervals, use the real time power readout to not exceed 362 watts (too hard) and to hold the effort above 306 watts. 

There are two reasons why you want a consistent power output for your intervals: First, there will be less pain and suffering! Second, by pacing yourself you'll actually be able to perform more intervals at the prescribed wattage.

In the "WRONG WAY" graph above the athlete's average power for the first interval is too high/above his prescribed zone and then because it was too hard, the athlete really starts to suffer and limps thru the next 3 intervals with the last one below the prescribed wattage. Thus the physiological adaptation is not achieved. From a sports psych perspective this 'performance' is discouraging for athletes. So the athlete went out too hard, underperformed, and limped home discouraged. Not optimal.

In the "RIGHT WAY" graph, the athlete paced himself properly and all four intervals were between the prescribed wattage zone. Plus there was less suffering and a feeling of accomplishment. By RPE the first interval wasn't 'that bad', the second wasn't either, the 3rd interval really 'hurt' (but the wattage was there) and the fourth interval was not only extremely hard but the athlete's power dropped off ~ 30 watts. That's a well paced and executed interval workout in my opinion and experience.

Here’s our motto of interval training:

Go as hard as you can BUT only as hard as you can maintain for the duration of your entire interval workout.

You’ll be able to do more intervals, recover in-between each, and start to see a big difference in your training, racing, and cycling performance.

For a step-by-step guide to performing intervals please read our training tip here.

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