VO2max, LT, Critical Velocity- They are much more messy than we think.
Maximum Lactate Steady State
What’s the point of the above? You may answer that they explain a physiological phenomenon. VO2max is when oxygen consumption plateaus. Lactate Threshold is a marker where lactate goes from a steady state or slow trickle of increasing lactate to a flood. Critical Velocity is the power output that can be sustained for a prolonged period of time without dipping into our W’ reserves.
But there’s another reason to define these. They all provide a marker for coaches and athletes to utilize. They represent a ‘transition’ point defining a certain ‘zone’ of training. We can define the velocity that elicits VO2max, the speed at Lactate Threshold, MLSS, or CV. It provides a marker in training that we can readily say “Today, we’re running at LT and it will give us these benefits.” In coaching, these parameters provide nice and neat little separation points between different zones of training.
The only problem? It’s not that simple. “For years we have seen study after study attempting to compartmentalize intensity domains based on an assumption that there is some physiological decompensation point. However we reach no clear consensus on this. First it was MLSS. Then VO2 kinetics. Then FTP and CP, but none are conclusive. Perhaps we are looking for something that isn’t there.” Dr. Jeroen Swart recently commented.
Dr. Swart is on to something here. We like order, we like to have simple and clear transition points in training. Something that separates easy from moderate and moderate form hard. And for years, VO2max, LT, etc. provided that. The only issue is that in the lab, it’s not so clear cut. As Dr. Swart outlines, we’ve searched for this holy grail only to realize that transition points are messy.
Unlike how many of us learned energy systems in our coaches education courses, there is no off/on switch, but a blending. And that Lactate Threshold or MLSS concept that looked so simple in the texts, requires a bit of guesswork to declare that X pace is my lactate threshold.
It’s not that any of these parameters aren’t useful or helpful. They all can be. They all explain a portion of performance.
But where we go wrong in the lab and out on the track is how we think about these parameters. We think of them as clear cut, defined markers. We run tempos at lactate threshold, 800m repeats at VO2max, and classify our training as such. We assume that the tranisition is clear and that these parameters represent some sort of boundary line. That above LT does this and below does that. That training exactly at Critical Power represents a magic zone where we aren’t yet ‘anaerobic’ or whatever we want to call it.
The body is incredibly complex. It’s not that we should discount short and easy physiological heuristics. They help center and guide training. VO2max, LT, MLSS, CP, and whatever else are all really helpful concepts.
But, we shouldn’t fall so in love with them, that we become blind to their flaws. Understand that these don’t represent a clearly defined transition, that physiology is messy. That training at them, above, or below doesn’t give us some magical benefit. They are more like shades of grey, telling us that in this ballpark of a pace, we’re more likely to be training X. That if you’re being anal trying to be exactly on X pace because it represents one of these parameters, you’re assuming way more accuracy and certainty then even the best science gives us.
Or as Dr. Mark Burnley’s lab found when searching for a ‘threshold’ for Critical Velocity, “These data demonstrate that the transition between heavy- and severe-intensity exercise occurs gradually rather than suddenly.”
Understand the science, but embrace the nuance. Don’t box yourself into zones or exact paces tied to some physiological parameter. When we do, we lose out on the creativity that allows you to do 100m repeats and get the same training effect of a 4mile tempo, or to utilize hill circuits to get the same effect of a grueling 400m repeat session on the track. Use the aforementioned parameters as a guide, written in pencil to help put you on the right path. But then utilize your knowledge of the science and the art to design workouts that stress an athlete to adapt in the direction you want.
Funnily enough I was reading pretty much the same thing a few hours ago, but about FTP, the cycling equivalent of critical velocity. Here’s the link, should you like to check it out : https://www.cyclingweekly.com/news/latest-news/whats-so-special-about-ftp-463782
Key points : as J. Swart suggested in his thread, Andy Coggan agrees that there’s no such thing as a physiological steady state, just different kinetics for different parameters. And maybe worst : according to S. Seiler, it deteriorates over a long duration.
Arguably the constraints of running are not the same as those of road cycling, but in the end the same conclusion can be drawn : reading too much into an intellectual construct that isn’t actually here in the physiology seems like a flawed approach (IME it’s been a common mistake among amateur running coaches obsessed with 100 % of vVO2max regardless of the distance their athletes are preparing for).