“His VO2 is 75, man, what a beast!”
In the world of endurance sports, one of the most common buzzwords is VO2 max, often referred to simply as “VO2”. VO2 max serves as a physiological benchmark that many endurance athletes- from amateur to pro- hold in high regard. It's a measure commonly used to determine training zones and stand as a bragging point among competitive friends. Perhaps most often it is used as a piece of impressive-sounding jargon we pull out when hoping to sound “legit.”
Measuring VO2 max can be a powerful training tool and performance predictor. But do we really understand what it is? Or how we can influence it? Or perhaps most importantly, how knowing our own VO2 max, or not, can help us make gains in our training and performance?
Okay, first a quick breakdown of what the term means. V stands for Volume, O2 for Oxygen. Said textbook-style, VO2 max refers to the maximum volume of oxygen a body can consume, per minute. This is not the same as the amount of oxygen you can breath in. Oxygen is processed by mitochondria to produce aerobic energy, which powers most of our daily activities, including almost all of our endurance pursuits. When our energy demands are such that oxygen is being delivered to our mitochondria and used to produce energy at 100% capacity, we have reached our VO2 max.
More oxygen being used to create more energy? Yes, please! If I keep training, and train harder, and do more intervals, will I increase my VO2 max? The answer is...no. Well, probably not. If you are an untrained, inactive individual, then yes, you will see an increase in your VO2 max of about 15-20% over a 20-week training plan. That's huge! But most people reach the genetically-determined upper limit of their VO2 max after about 12 months of training.
Okay, okay, so does VO2 max matter, if we can't do much about it after one year of training? It is true that a high VO2 max often corresponds to high-level performances for endurance athletes. But is it the end-all, be-all? Thankfully, no.
Once we have reached the point where our VO2 max is no longer increasing, we need to add two new buzzwords to our vocabulary: economy and lactate threshold.
Economy refers to the efficiency of oxygen usage, which is influenced by everything from body structure to technique to muscle fiber composition. Two skiers with the same VO2 max skiing at the same speed will last different amounts of time if their economy differs. This is the vehicle-fuel-efficiency equivalent for athletes.
Lactate threshold refers to the percentage of an athlete's VO2 max at which blood lactate levels begin to increase significantly above resting levels (blood lactate levels increase gradually at first, and then spike once lactate threshold is reached.) As athletes, we want this point to be at the highest possible percentage of our VO2 max. Said simply, the higher the lactate threshold, the harder we can go, for longer, with less blood lactate accumulation. This is especially critical for any sub-maximal, high intensity effort, meaning any high-intensity effort at which we are utilizing less than 100% of our VO2 max. This means just about any race 5k or longer, for Nordic skiers and runners.
If you're still wondering about the point of training something that can't be improved beyond a certain point, it's also worth noting that VO2 max decreases by approximately 1% per year for inactive folks over the age of 25 years. That's fitness potential you can't get back, so better not to lose it in the first place!
We've concluded that VO2 max does matter, but that there are other factors just as important to our fitness and potential for endurance success. The last big question is, what should we be doing in training to maximize these components?
Improvements in economy result mainly from improvements in technique. Sport-specific exercises targeting strength, balance and proprioception are key in making your movements more energy efficient and teaching your body over time to recruit fewer muscle fibers to get the same job done. Repeating these motions during aerobic training reinforces the neural pathways that will make efficient technique more natural. Consult your coach for the best exercises related to your target sport. It's these seemingly small details that fill in the gaps and allow athletes to reach higher levels than they can attain from focusing on aerobic training alone.
Endurance training also means raising lactate threshold through intervals, often referred to as “threshold” intervals if they are performed at the percentage of VO2 max corresponding to the lactate threshold, and “sub-threshold” if performed just below this range. This is where knowing your VO2 max comes in useful, as you can set training zones that correspond to it, measured by heart rate. If your lactate threshold occurs at around 75% of your VO2 max and 75% of your VO2 max corresponds with a heart rate of 160 beats per minute, you know know that your threshold intervals are most effective when your heart rate is around 160.
Unfortunately, the testing and calculations required to learn our VO2 max, lactate threshold, or even heart rate are not readily available to many recreational or Masters level athletes. Luckily, there are other ways to effectively gauge your training effort. Ever tried to run a short race, 3k or so, or attempted 8-10 minute intervals on the bike or on skis, and felt great for about three-quarters of the interval before hitting the wall and crawling the rest of the way? You just exceeded your lactate threshold, and this is a critical experiment. To zero in on your lactate threshold, hit the track for a 3k running time trial, and pace so that you are nearing collapse at the end of the TT, but not before. This effort should put you at your VO2 max.
With practice, you will come to recognize this pace when performed off the track, in other sports, and for varying durations. You can also take your heart rate at the end of your time trial, or during if you have a heart rate monitor, and set training zones based on this value.
The specifics of how to accurately set training zones “by feel” could be an article in itself; this blog post has barely covered the basics. If you are a recreational or Masters level athlete and haven't yet done so, be sure to consult your coach about the role of VO2 max in setting training zones.
And by all means, the next time your friend and Strava competitor asks you what your VO2 max is, show off your newly acquired expertise, and forward them this article.
For more posts about effective training and musings on the nature of the life of endurance athletes, and to send me questions or check out my coaching options, visit me at www.enduranceefficacy.com where I offer online personal coaching for endurance athletes. Benefit from support, accountability and flexibility with customized training plans and consultation geared at maximizing the efficacy of your workouts!