Z4: Aerobic power (The Spicy Zone!)

Today we’re kicking it into maximum VO2 over drive and talking about the aerobic power zone. More specifically I’ll be taking time to discuss VO2max vs velocity at VO2max (vVO2max), the benefits of training in this zone, and how to design and structure aerobic power training!

Before we get into the article here’s a quick explanation of what I consider the aerobic power zone. This zone includes anything above LT2 or Critical Velocity (CV) and up to your VO2max. In terms of effort this includes anything above your 10k effort up to your 1mi race effort. This zone is where you have gone past your lactate thresholds. Which means running in this zone will flood your body with lactate. At the top end of this zone your aerobic system reaches its limits and maxes out. Think of this as your aerobic ceiling.

(If you want to learn more about how I think about other training zones check out this article here)

What happens to your body when you are training in the aerobic power zone?

We improve VO2max:

VO2max is the maximum rate of oxygen your body can consume during exercise and is typically normalized by weight. Generally speaking, there is a positive correlation between VO2max and performance. Oxygen is needed to generate power. So the more oxygen your body can consume and process the better it will be able to perform. It makes sense that if we train at your VO2max or just below it we will be stressing and adapting the physiological systems that affect VO2max.

We improve cardiac and respiratory function:

The main systems that effect your VO2max will be your cardiac and respiratory systems. There will be various slight improvements across both systems, but the largest driver of VO2 max improvement here will be improvements in stroke volume. Aerobic power training helps to strengthen the muscles of your heart so that it can pump more blood and deliver more oxygen with every beat. Now there is some good news and some bad news here. The good news is we can hit our peak cardiac output relatively quick making this a great form of training to quickly boost your fitness! The bad news is since we hit peak relatively quickly only doing this type of training will cause us to plateau. So, this type of training is best used sparingly and in conjuncture with lots of foundational work.

We increase muscular strength and power output:

While it gets a lot of attention VO2max really isn’t our end goal. In all honesty VO2max is really just a metric used by runners to brag to each other and a metric that makes cross country skiers feel superior to everyone else. Instead of VO2max, I like to focus more on vVO2max. VVO2max is the minimum speed needed to reach your VO2max and typically for the average runner sits around your 1mi to 3k race pace.

VVO2max tells us a lot more about performance than VO2max when comparing athletes with similar capabilities. For example, let’s say we have athlete A with a VO2max of 55 ml/kg/min and athlete B with a VO2max of 60 ml/kg/min. Who’s faster? You may think athlete B is obviously faster but if athlete A has a vVO2 of 5.00min/mile and athlete B has a vV02max of 5.25min/mile, then I am putting my money on athlete A. At the end of a day what matters most is how you translate that oxygen you are consuming into forward motion.

The main reason I like to emphasize this type of training year round even though you hit an aerobic plateau rather quickly is because like the anaerobic zone we can continuously improve our high power output capabilities. But unlike the anaerobic zone we can maintain efforts in this zone for much longer (around 40-5min depending on which side of the zone you are on). Meaning the strength you gain hear will be more applicable to aerobic events (events >2min). Also, even if we reach our peak VO2max we can continue to improve our vVO2max by improving our running economy at our aerobic max.

Why do we care about the aerobic power zone?

Well, if you are doing events from 10k – 1mi races then your races will take place directly in this zone. So, training in the aerobic power zone will specifically prepare you for those events.

If you are interested in doing races longer than 10k this zone is still incredibly important. The max muscular and aerobic power output you can generate here will trickle down to all zones below this one. The increase in stroke volume I mentioned doesn’t just occur at VO2max, it occurs across efforts. Which means you can generate the same cardiac output and deliver the same amount of oxygen with a lower heartbeat (CO= HR x SV). Having a higher vVO2max will also make lower thresholds subjectively and physiologically easier for you to maintain. Not to mention having extra power capabilities can come in handy during pace surges and when you get to steep climbs.

How do you implement it in your own training?

Hopefully at this point I have convinced you of the usefulness of aerobic power training. So, now let’s focus on how to implement it into our training. Free training advice time!

As I mentioned earlier, we don’t constantly want to be doing this sort of training because it will cause our aerobic system to plateau. Not to mention that this intense of training is extremely stressful on your body. Typically, I like to limit aerobic power workouts to 1 to 2 times per week. Even then, unless an athlete is specifically training for an aerobic power event if I assign two aerobic power workouts, I will usually make them two less intense aerobic power sessions. Also, if you are training for an event longer than 10k I recommend you do this style of training earlier in your training cycle to build up speed then shift to more race specific workouts (like tempos) as you get closer to your event.

There are a few important considerations to take into account when designing workouts for aerobic power. To achieve what we want aerobically we either need to make sure our intervals last long enough to actually work up into the zone we are targeting or do shorter reps with shorter rest intervals which don’t allow your body to fully recover in between reps. We typically need 2-3min to reach an aerobic steady state where our VO2 plateaus signifying we have burned off your anaerobic work capacity. However we can still have a successful aerobic power session with shorter intervals if we don’t give your aerobic or anaerobic systems enough time to fully recover in-between reps. We can do this with short rests (≤1:1 ratio of work to rest) or with float rests in which you continue running at a moderate effort during your recovery to prevent your aerobic rate from dropping.

Here are some example aerobic power workouts to start implementing in your training:

In n’ Outs:

20min easy, 6-15x 1min fast/ 1min moderate, 20min easy

This is one of my favorite workouts. Not just because I am a California boy with a soft spot for In n’ Out, but because it’s just plain fun! This is a great starting workout for athlete’s new to aerobic power training or for those who haven’t trained in this zone for a while. As with all aerobic power workouts we want the pace to be hard but not all out. Pace control is important because if you go too hard you’ll end up just training the anaerobic zone and missing the goal of improving your aerobic power. So faster is not always better! Going back to the talk test, you should at least be able to get one word out when training in this zone.

Hills on Hills:

20min easy, 4-6x 2min hills @5k effort with jog down recovery, 4-6x1min hills faster with jog down recovery, 20min easy

If you are new to this aerobic power style of training I also recommend you start with hills like these. Running on hills will reduce impact on your body compared to running on flats. Then having a combo of 2min and 1min hills helps you to ease into longer intense reps. You get to do the 2min reps when you are fresh but as your body fatigues you will shift to 1min hills so we can still hit vVO2max.

I can’t believe it’s not K’s:

20min easy, 4-6x 3min @5k effort/ 2min easy, 20min easy

Kilometer repeats (or K’s) are a staple of elite training teams around the world. Part of their magic is they sit around the 3min range for most elite athletes. For mortals who cannot hit those crazy paces it is better to replicate this workout based on time instead of distance. 5k effort is in the middle of the zone so more often than not I will assign 5k effort for aerobic power training. By targeting the middle of the zone we have less risk of over running and ending up in our anaerobic power zone or under running and ending up in our tempo zone. I love doing this one on flat ground to really increase speed for road and track races. But my favorite way to run this one is by doing it over rolling hills. For trail races this workout is awesome for practicing transitioning pushing downhills to pushing uphills. But only attempt this work if you are not injury limited and have a solid base because this will be a huge structural stress.

Mock Sac:

20min easy, 3min @5k effort, 3min easy, 3x3min hills@5k effort with run down recovery, 3min @5k effort, 20min easy

Named after the historic Mt. SAC XC race known for its flat start/ finish and hilly middle, this one tests your speed and fatigue resistance. We start flat and fast, pummel your legs with eccentric contractions on the hills, and then see if we can maintain or improve the speed we had at the start of the workout.

You should now have everything you need to understand the reasoning behind aerobic power training and how to implement them into your own training! So go forth and be aerobic monsters!