Hard Enough: Training to Increase Your Anaerobic Threshold and VO2 Max

GRP Rower Jen Forbes and GRP Ski coach Pepa Miloucheva during a VO2 max test.

From Troy Howell, Director of Sculling

Previous posts in this series: Training at the Bookends and The Other Bookend

VO2 max and anaerobic threshold (AT) are arguably the twin holy grails of endurance athletes. In simple layman’s terms, the former is a simple measure of the volume of oxygen the athlete’s body can process in a minute. The latter is the heart rate and intensity at which the byproducts of anaerobic metabolism begin to accumulate in the blood, a tipping point between the comparatively comfortable world of purely aerobic efforts and the less sustainable work of anaerobic efforts. Increasing either of these numbers creates the ability to produce more power from purely aerobic work, and almost always results in greater sustainable speed over the course of a race or training session. These are not difficult concepts to grasp: if your maximum heart rate is 200 and your anaerobic threshold improves from 140 to 165, you can do work at a substantially higher intensity without encountering the discomfort that inevitably follows exceeding your AT, and how could that not be a good thing? Likewise, if your VO2 max goes from 48 ml/kg to 62 ml/kg, your working muscles will have access to considerably more oxygen, and what’s not to like about that?  

Virtually any work that an athlete does on a recurring basis that is primarily anaerobic will produce adaptations that will result in gains for both numbers, and this is the primary justification for interval training, which demands that you work at an unsustainable pace for a comparatively short duration, rest, and repeat. That being said, some specific workouts have been extensively studied and shown to produce particularly noteworthy gains in AT and VO2 max.

The orthodox gold standard workout is a simple and intense one: equal work/rest intervals at or near race pace repeated until the chosen pace becomes unsustainable, e.g. 2’on/2’ off, 3’on, 3’ off, 4’on/4’ off, etc. Equal rest does not allow for full recovery from near-race pace efforts, so the net physiological effect is that as the workout progresses, you are working from a progressively less “full tank.” Intensity must progressively increase with each successive piece in order to maintain your pace, and after enough repetitions, you’ll reach a point at which there is nowhere left to go - your heart rate has reached its limit and acidosis in the muscle tissue will no longer allow the power output required to maintain speed. At that point, the workout is over - physiologically, at least. You can continue to do pieces if you want, but when your power output has dropped off by more than 3%, you’re probably doing your physiology more harm than good by increasing the time you’ll need to recover from the extra work involved in taking yourself past the point of depletion, and in any case, there are far better ways to train your mental toughness and tenacity than by rowing badly with intensity. Note that the number of intervals in this workout is dependent on the ongoing quality of the work. As long as your pace is getting faster or holding steady, keep going, whether that means 4 x 3 minutes or 14 - though if you can get to 14, you’re either a physiological marvel, or you’re capable of going much faster - probably the latter. A pretty good indicator that you’re getting close to the end of the set is when your heart rate doesn’t drop below 60% of max by the end of the rest interval. When that happens, you can be fairly certain that one of the next two pieces should be your last of the day. 

In the past ten years or so, a much shorter workout has gained a lot of credibility as a means of increasing VO2 max and anaerobic threshold, based on the protocol of Japanese physiologist Izumi Tabata. This is a much-misunderstood workout, largely because too many trainers have mislabeled their own workouts as “tabata” and in doing so have departed from the strict protocol of the original, which is this: 20 seconds of flat-out sprint, 10 seconds rest, repeated 8 times. The idea is to attack each of the 20 second intervals at the highest speed and intensity of which you are capable, rest completely for 7-8 seconds, and build for 2-3 seconds for the next interval. With only ten seconds between sprints, you are going to see a significant drop-off in speed and power from the first interval to the last, but the idea is to use everything you have left in the tank on each interval. It might be the only workout I’ve seen in which a fly-and-die mentality is genuinely encouraged - or perhaps it is better framed as “fly eight times and then die” lest you set up too great an expectation of how difficult reps 6, 7, & 8 are going to be. And they are, but the whole thing is over in just under four minutes. It is a ton of fun, though, if you’re at all jazzed about the opportunity to just cut loose and honk on it at very high stroke rates. In Tabata’s original experiment, already-fit athletes keep up a steady diet of nothing but Tabata intervals and easy steady state (I believe it was 5X/week for the sprints), and at the end of the four weeks, their VO2 max had increased an average of 10% more than the athletes in the experiment who were following a more traditional training program. N.B. we would recommend looking up the history of the experiment before embarking on a full month’s worth of Tabata. That said, if you are pressed for time or just looking for some spice in your training, I don’t think there’s a better bang for the buck workout out there. It should go without saying that a thorough warm-up is required, but in case it doesn’t, we’ve said it. For more information on Tabata, start here:

How Tabata Really Works: What The Research Says

The Real Tabata: A Brutal Circuit From The Protocol's Inventor

Have fun. Go fast. These are the hard workouts that demand to be done hard enough.