VO2 Priming Before Hard Intervals

TOOLBOX: VO2 priming, also known as pre-conditioning, is a training technique utilized in sports performance to optimize aerobic capacity and enhance endurance. By engaging in brief, high-intensity exercise prior to the main training session or competition, athletes aim to stimulate physiological adaptations that improve the body’s ability to utilize oxygen more efficiently during subsequent exercise.

In May the flowers are in full bloom, each week is a little warmer than the last, & the Giro d’Italia confirms that spring season is in full swing. I hope your outdoor season is off to a great start & that you’re able to start racking up those outdoor miles!

In this month’s toolbox article, we will be discussing a training technique known as ‘VO2 Priming’.

VO2 priming involves short bursts of intense effort followed by a recovery period, which serves to ‘prime’ the cardiovascular system, respiratory system, and muscles. This technique aims to elevate oxygen uptake, enhance metabolic responses, and improve neurological readiness, ultimately leading to improved performance in endurance activities. While VO2 priming is typically employed by well-trained athletes, its protocols and integration into training programs should be tailored to individual fitness levels and training capacities for optimal results.

Understanding VO2 Max and its Significance

We have discussed VO2max in Toolbox articles before, but it never hurts to refresh. VO2max, or maximal oxygen uptake, is a measure of an individual’s maximum capacity to utilize oxygen during intense exercise. It represents the highest rate at which oxygen can be consumed and utilized by the body’s muscles during physical activity. VO2max is often considered a key indicator of aerobic fitness and endurance performance.

Since VO2max represents a maximal rate of oxygen process over time, it can be expressed in absolute units (Liters/min). However, it’s more often expressed as milliliters of oxygen consumed per kilogram of body weight per minute (mL/kg/min). By normalizing oxygen uptake to each athletes’ body weight, VO2max can be compared between athletes of different sizes.

VO2max reflects the efficiency of each athlete’s cardiovascular system in extracting oxygen from the air & delivering it to working muscle. While much of your VO2max is genetically determined, it can also be trained, and is often used as a valuable indicator of aerobic fitness and endurance capacity. Higher VO2max values generally correspond to improved cardiovascular fitness and the ability to sustain higher-intensity exercise for longer durations.

Exploring VO2 Priming

As we discussed in the introduction, VO2 priming is a strategy to optimize aerobic efficiency. Sounds great, but how does it work?

VO2 priming consists of heavy intensity exercise prior to the main training session. The priming work is thought to accelerate the VO2 response during subsequent exercise, thereby increasing athlete’s time to exhaustion for efforts above FTP. These improvements in performance are achieved without any change to the athlete’s Critical Power (analogous to their FTP). To summarize, VO2 priming helped athletes achieve an increase in time to exhaustion above FTP (e.g. how long you could hold 500 W would increase, despite no change to your FTP. Free gains!

The suggested mechanism behind VO2 priming is still under debate today, but is considered primarily from the change in VO2 kinetics and an increase in VO2max. Put another way, ‘priming’ helps your body achieve higher rates of oxygen utilization more quickly. Priming may also help athletes achieve a higher VO2max than when tested without any priming. When priming is provided with adequate recovery, these improvements can all be achieved without fatiguing your body too much for subsequent intervals.

For a more detailed review on the underlying mechanisms of VO2 priming, which are still under debate in the scientific community, I recommend reading the 2023 review article linked at the bottom of the article.

Implementing VO2 Priming Techniques

Given all the claimed benefits of VO2 priming, how can you implement it as part of your own training? I’d like to quickly point out that VO2 priming is helpful for performing work above your FTP. Therefore, priming will be most effective before high intensity sessions, and relatively unnecessary for low-intensity/endurance training sessions, since those sessions aren’t limited by your VO2max.

In the study mentioned above, the authors showed that only 6 min of heavy exercise (roughly sweet spot intensity) followed by a short, 10 min recovery was effective for VO2 priming. They also showed that severe, or near-maximal, exercise was not effective.

I recommend that you experiment a bit to find what works the best for you. In my personal experience, I have found that adding in a few short (~30s), hard intervals  at my 5 min power helps me feel more prepared for a hard interval session. Below is an example of one of my favorite Xert workouts, which features an extended warmup with a few bursts (depicted in the yellow intervals) that helps prime me before a set of 30-30’s until failure.

Since I’m fortunate to live somewhere with straight, relatively quiet back roads, I often like to experiment with various outdoor workouts. However, in order to reach the quiet back roads out of town, I need to climb up a steep hill – about 300 m long at 7% grade, which takes 40-60s to climb. I’ve found that a harder push up the hill, followed by some recovery at the top, helps my legs (and my mind) feel more prepared for the intervals to follow. Below is an example of a sprint workout I did last week with a few min at sweet spot followed by a short, 45 s push up the hill. After the hard push, I recovered for about 9 minutes before starting with my 30 s sprint intervals.

Conclusion

In conclusion, VO2 priming can be a useful technique for athletes aiming to optimize their performance. By engaging in high-intensity exercise prior to the main training session, athletes can stimulate physiological adaptations that enhance their VO2 max. The benefits of VO2 priming include improved oxygen uptake and increase time to exhaustion. With careful implementation, VO2 priming can be a powerful addition to your training and help you reach new levels of performance.  Consider incorporating VO2 priming into your training routine and experience the potential benefits in your athletic pursuits.

That’s all for this month. Stay safe, ride fast, and I’ll see you next time!

References

BURNLEY, MARK; DAVISON, GLEN; BAKER, JONATHAN ROBERT. Effects of Priming Exercise on V˙O2 Kinetics and the Power-Duration Relationship. Medicine & Science in Sports & Exercise 43(11):p 2171-2179, November 2011. | DOI: 10.1249/MSS.0b013e31821ff26d

Goulding RP, Burnley M, Wüst RCI. How Priming Exercise Affects Oxygen Uptake Kinetics: From Underpinning Mechanisms to Endurance Performance. Sports Med. 2023 May;53(5):959-976. doi: 10.1007/s40279-023-01832-1. Epub 2023 Apr 3. PMID: 37010782; PMCID: PMC10115720.