Your VO2max is the maximal amount of oxygen consumed during progressive all-out exercise. In the weight conscious world of cycling, VO2max is most commonly discussed in relative terms scaled to a riders weight as milliliters of oxygen, per kilogram of weight, per minute of exercise mL/kg/min.

A true measure of VO2max uses expired gas analysis alongside power measurement during a ramped test to exhaustion. In an applied cycling context, “VO2max” generally refers to the approximate power output that is most likely to correlate to a riders maximal oxygen consumption. In technical terms this is referenced as your power at VO2max or pVO2max.

Most of the time, we strip away all of technical jargon and are left with simply “VO2”. In general, when we reference Zone 5, or “VO2”, we’re referencing a duration and intensity of effort designed to boost a riders maximal aerobic capacity. For most cyclists the maximal amount of power you can produce for about 4 minutes serves as a good proxy for your power at VO2max [1]. It’s no wonder why most VO2 intervals utilize the two to five minute duration for intervals [1]. 


Short on time? Check out our quick tips for VO2 workouts.

Context

So why should you care about yet another (alongside the lactate threshold) lab-based training metric? Although VO2max doesn’t do a very good job of predicting your performance [2], it does help to define the upper limit of your cycling potential, be that world class or local hero [3].

In simple terms, if your VO2max is limiting your progression on the bike, or if you’re a masters athlete who via the aging process is losing maximal aerobic capacity year over year [4], it makes sense to set aside significant time and focus in your training to push against your aerobic ceiling and see if raising your roof might open up a wider range of performance capacity.

In short, riders who train their VO2max will be fitter and faster than those who don’t.

While nearly all forms of riding can improve your VO2max, High Intensity Interval Training (HIIT) is a foundational tool for boosting your performance limit as a cyclist. HIIT is also an efficient strategy for time-crunched cyclists aiming to improve their performance across their power curve with less time investment [5].

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Warming Up

With training  zones one through three we don’t pay much attention to  warming up before our workouts. In general I recommend athletes getting in whatever type of warmup (long, short, easy, or hard) that feels right. Once we go beyond a threshold territory the specificity of our warmup becomes more important.

In short, for higher intensity (≥zone 4) workouts, research suggests that utilizing a short, higher intensity ramp before your primary efforts can help to “prime the aerobic pump” of exercise, resulting in improved performance for subsequent hard riding. To read more about the science and theory behind a great warmup, check out this post over at our blog.


Warmup Template

If you prefer to jump straight to the goods, here’s a template for a science-backed warmup to execute before all (training or racing) your high-intensity efforts.

This template is for a 20m warmup. Fine-tune your intensity and rest duration before the start of the main set to see what works best for you.


Now that we’ve covered a good warmup to use before your VO2 rides, lets take a look at the two different interval patterns we’ll most frequently use to improve your VO2max.


HIIT-long

These are two to five minute intervals with one to four minutes of rest between intervals.


HIIT-short

These are ten to sixty second intervals with ten to sixty seconds of rest between efforts. Usually broken up into two or three series of efforts lasting four to ten minutes in total. 


Energy System Target

VO2 workouts target a maximal response from the oxidative energy system, while also activating the ATP-PCr & glycolytic energy systems. During VO2 efforts, all three energy systems rely on carbohydrate nearly exclusively as a fuel source. 

Nutritional Considerations

Like all other workouts north of our Zone 4, paying close attention to high carbohydrate availability in the hours before your ride will insure you are going into each VO2 workout with adequate fuel to nail a high quality workout. 

If you’re only able to ride in the morning coming off an overnight fast, or if you’re experimenting with restricting carbohydrate, dosing caffeine about one hour before your VO2workout has been shown to free up extra watts, even in the absence of adequate glycogen [6].

In short, do your best to fuel adequately with carbohydrate before your VO2 workouts, in addition to considering caffeine if you plan to ride in the morning.  

It goes without saying that making sure you’re well hydrated in the hours before your VO2 rides is an additional requirement of getting a best effort.

Pacing

Screen for VO2 rides

If you do use power to pace your VO2 efforts, limiting your display to the bare essentials needed for interval pacing can help to narrow your focus.


On one hand, pacing HIIT gets simpler the further you move up the intensity continuum where specific power targets based off a percentage of your threshold become less meaningful than RPE to guide your effort. Why is this the case? 

In simple terms, while the aerobic contribution to power output is reasonably consistent across the spectrum of cyclists (i.e. threshold-based power targets work well for nearly everyone between zones one through four), the anaerobic contribution to power output can vary greatly between cyclists, making threshold based power targets less consistent for Zone 5 and 6 efforts.

This difference in the aerobic/anaerobic contribution to cycling can be seen by observing the different body types of cyclists.  Riders with a more muscular build generally have a higher percentage of type II muscle fibers which rely more heavily on the ATP-PCr & glycolytic energy systems (anaerobic). Riders with a slighter build, with less type II muscle fiber, naturally produce power for VO2 efforts utilizing a larger contribution from their type I muscle fibers, which in turn rely more heavily on their oxidative energy system (aerobic).

While VO2 intervals are primarily aerobic in nature, they are still driven by a large anaerobic contribution from your ATP-PCr and glycolytic energy system. What this means in a practical sense, is that accurate targets for VO2 (and ATP-PCr & glycolytic) intervals can vary widely between riders. 


This graphic highlights the estimated energy system contribution to an all-out 4m effort

Under the hood of a 4m all-out effort

VO2 type efforts are designed to place maximal stress on your body’s ability to produce the most power possible via the oxidative energy system (aerobic metabolism).


Some riders with large “anaerobic” engines might need to aim for the upper range of a VO2 target (or above target) while those riders with a smaller “anaerobic” engine might be better suited for the lower end of a VO2 target.

The important thing to remember is that VO2 and above efforts will likely require some fine tuning through the process of training. The best thing to do is to jump in, observe your power output and RPE for a set workout, and reconfigure your targets for future workouts if necessary. 

Reducing RPE

HIIT workouts are kind of like magic. For a considerably shorter time investment, you can reap improvements to your fitness across the power curve. What’s not to love about that? Well, there’s one primary downside to HIIT workouts, they peg the RPE scale.

High RPE is the main reason why the decision to utilize HIIT should always be careful and deliberate. While HIIT can do wonders for your fitness, it doesn’t come for free, and in the larger perspective of training, short-term increases in your performance aren’t worth long-term burnout. 

That last bit is so important I’ll repeat it again.

Short-term increases in your performance aren’t worth long-term burnout.

With that in mind, here are a few methods to reduce RPE for VO2 workouts. 

1. As best as possible, utilize visual landmarks to define your intervals. Sometimes this isn’t feasible, but when possible, try to translate the duration based structure of a workout to the terrain based structure of a favorite climb. If your workout calls for 4X4 type intervals, try thinking of a local segment where you might be able to get close to that duration. The exact duration of the interval isn’t super important. If you can find something in the three to five minute range, call it good. 

2. Create a custom playlist of music you only cue up for your VO2 HIIT work. Taking a bit of time up front to line up your most motivating songs can lower RPE and boost your watts. If you can find songs in the 3-5 minute duration you could also utilize the length of your song as the interval. Try delegating the responsibility of keeping track of your interval duration to an external source (the music). Slot in some slower songs for rest intervals and you’re good to go.

3. To the degree it doesn’t negatively impact your sleep, strategically utilize caffeine in the hour or so before your workout. Free watts with less RPE.

4. Perhaps most importantly, assess your relationship to HIIT. Do you find it drains your motivation to ride? If this is the case, see where you can strategically dose HIIT inside the context of competition. Races, group rides, Strava challenges, it might make the most sense to delegate all your HIIT interval motivation to a competitive environment and ditch the structured workouts all together.

Knowing your tolerance for structured workouts (and avoiding them when necessary) can greatly increase your enjoyment, and sustained performance on the bike. No VO2 workout is worth quitting the bike over.

References

  1. Laursen, P. and M. Buchheit, Science and application of high-intensity interval training : solutions to the programming puzzle. 2019.
  2. Coyle, E.F., Integration of the physiological factors determining endurance performance ability. Exercise and sport sciences reviews, 1995. 23: p. 25-63.
  3. Hawley, J.A. and T.D. Noakes, Peak power output predicts maximal oxygen uptake and performance time in trained cyclists. European Journal of Applied Physiology and Occupational Physiology, 1992. 65(1): p. 79-83.
  4. Valenzuela, P.L., et al., Lifelong Endurance Exercise as a Countermeasure Against Age-Related [Formula: see text] Decline: Physiological Overview and Insights from Masters Athletes. Sports Med, 2020. 50(4): p. 703-716.
  5. Gibala, M.J., et al., Short-term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance. The Journal of Physiology, 2006. 575: p. 901-911.
  6. Lane, S.C., et al., Caffeine ingestion and cycling power output in a low or normal muscle glycogen state. Med Sci Sports Exerc, 2013. 45(8): p. 1577-84.