What It Means To “Base Build” And How To Do It

You have probably heard people say you should “build your base” and “run mostly easy.” If you’re anything like me when I started out, you put that advice in the same mental box as the people that say “pay attention in history class” or “floss daily.” Teachers’ pets, every single one of them. Don’t you want to live on the edge like the cool kids that shoot spitballs in the back of the room?

Eventually, you learn that the cool kids all failed history and have 28 cavities from not flossing. So let’s use this article to dig into the basics of base. What is it? How can you build it? Was it over when the Germans bombed Pearl Harbor? Damn … I should have paid more attention in history class.

Lydiard Training

Widely described as the father of modern endurance training, Arthur Lydiard used what amounts to a block-periodization model that began with a base phase starting in the 1960s. This phase was designed to build aerobic fitness to prepare for more race-specific training to come. Lydiard framed base as building up the cardiovascular system maximally before being able to develop the muscular system maximally.

Even at these early stages of modern training theory, there are slight disagreements on what constitutes a Lydiard base, partially due to contradictions in his two major books. Most Lydiard bases were not just easy running, but included what we’d now call a steady run (possibly marathon pace) and a fartlek run with intervals between 30 seconds and 5 minutes (to develop leg speed). While the running was not all purely slow, Lydiard did not want athletes to build up “lactic acid.” We now know that lactic acid is a misnomer when it comes to fatigue, but the point stands even as we can dunk on him with our modern exercise-physiology knowledge.

Another problem that will come into play later: Lydiard got famous by training very talented, high-volume athletes. For them, easy running was rather fast, and steady running very fast, and leg speed faster still. Those Ferraris in second gear are still faster than my Kia Soul with the pedal to the metal. We’ll get back to why that matters at the end of the article.

MAF Training

Maximum Aerobic Function training was put into practice by doctor and coach Phil Maffetone in the 1980s, taking some of the base principles to their logical conclusion. It’s like that scene in The Social Network. You know what’s better than a million aerobic points? A billion aerobic points.

Boiling it down to a simplified glaze, MAF training involves lots of aerobic volume under a heart=rate cap (often classified as 180 minus age). The reasoning is that exceeding approximately aerobic threshold curtails aerobic development through changing muscle-fiber recruitment, enzymatic activity and stress-hormone production, and reducing lipid metabolism efficiency. MAF base blocks are often at least three months long, and the principles were used to great success by triathlon champion Mark Allen, among others.

Maffetone provides a disclaimer that MAF training may be painfully slow for many athletes. That raises a slight complication that will also come into play later. How much aerobic volume does it take to override the neuromuscular and musculoskeletal stagnation from painfully slow running?

Clearly, it works for some athletes like Mark Allen, talented humans doing a ton of training. There are plenty of converts that aren’t Ironman champions too. However, anecdotally, I have received plenty of emails over the years from people saying they have just become painfully slow from strict heart-rate-capped training. So response rates vary. And Maffetone would acknowledge that it’s more complicated than the simple formula to achieve peak performance.

Aerobic Deficiency Syndrome

A nuanced, trail-specific application of some of these principles comes from Steve House and Scott Johnston in Training for the New Alpinism. They use the term “aerobic deficiency syndrome” (ADS) to describe aerobically underdeveloped athletes, prescribing lots of activity below aerobic threshold to rectify the offset (along with other training elements). It clearly works. Kilian Jornet ascribes to the principles, and Kilian is so fast that he can flip the switch and be in bed before the lights turn off.

House and Johnston have a great system that latches onto a reality unique to trail and mountain athletes: going uphill is hard. It’s really difficult for some athletes to avoid making every day a bit too hard without knowing it. That causes aerobic efficiency to tank over time from what amounts to overtraining, even as it feels sustainable in the moment. ADS thus acts as a shorthand to describe underdeveloped aerobic base from too-intense training.

Canova Introduction Period

Renato Canova coaches many of the fastest track and road runners ever, so his methods clearly excel when the margins of human performance are tested. His General Period starts with an Introduction Period (lasting six to eight weeks usually) for development of muscle efficiency and aerobic endurance. The Intro Period involves easy running, steady runs, progressive runs and short strides.

It’s hard to reconcile things like Canova and MAF partially because of how much individual response may depend on genetics and background. Canova athletes likely have MAF paces that are shockingly fast. And you probably don’t become a Canova athlete by being a bit of an aerobic monster to begin with.

Aerobic threshold and what it means

All that training talk essentially revolves around the idea of aerobic threshold (AeT). AeT is the intensity where the body switches from relying primarily on lipid oxidation for fuel to glycogen. Easy to moderate. Fat to carbs. That last sentence just made our keto readers scream.

It’s helpful to think of AeT as a range that varies based on stress, training status, background and other variables. Going above AeT by going too hard too often counter-intuitively slows athletes down. That’s where base comes in. On top of building musculoskeletal health and resilience, base training primarily below AeT does three main things that help you run really fast later.

Increase density of capillaries around muscle fibers

Angiogenesis is the process of capillary growth, and it can occur due to functional demands like those from running, largely by stimulating production of vascular endothelial growth factor (VEGF). More intense exercise may actually impair angiogenesis and VEGF production (see this 2015 study from Experimental Physiology and this one from 2016 in the Scandinavian Journal of Medicine and Science in Sports).

Increase recruitment of Type I ST muscle fibers

You’re born with a certain breakdown for muscle-fiber composition, and it’s debated whether and how much that can shift over time (see this article in the Journal of Strength and Conditioning Research). Either way, easy running should make your slow-twitch fibers more efficient (partially through our old friend, angiogenesis), and your fast-twitch muscles act more like slow-twitch fibers.

Improve oxygen processing

This is a catch-all bullet point designed to encompass aerobic enzyme activity, mitochondria biogenesis, lipid oxidation/metabolic factors and feedback loops between the neuromuscular system and cardiovascular system and musculoskeletal system.

Basically, training aerobically with oxygen gets you better at using oxygen, and the exact pathway of each adaptation is tough to pin down. Heck, Lydiard had an antiquated view of exercise physiology and figured most of modern training theory out through being smart and perceptive.

Caveat: aerobic development is just one component of running economy, and pure aerobic training can make some athletes slower.

That’s all a long-winded way of getting to this point: running is not just oxygen processing. We aren’t lungs with legs, otherwise Tour de France cyclists would be amazing runners with just a bit of training. Lance Armstrong ran 40-plus minutes slower than the world record in the marathon, even with all the drugs known to man and horse.

Aerobic development feeds back into neuromuscular, biomechanical and musculoskeletal development. It takes a special athlete to get fast by just running slowly because running fast is a complex task that is developed over many training cycles.

A helpful way to think about it is in terms of limiters. Many athletes face aerobic limitations—that’s where something like ADS comes in. However, as the aerobic system develops, the actual ability to go fast or put out more power may become just as much of the limiter.

For a talented athlete, this caveat may be unnecessary. They have genetics that want to go fast, so they can raise the aerobic bar to the ceiling and their legs will catch up. For others, their legs stay on the floor and they just get good at going slower. Most likely, those athletes can play catch-up by going into more specific phases that develop speed and economy after building their bases. But, in general, aerobic development and speed development probably don’t need to be thought of separately.

Developing the aerobic system and speed together

Why is this article so long? If I hit 2000 words, I’m hoping Trail Runner gives me a Christmas bonus of two expired gels lying around the office.

All that background and all those caveats were designed to help you understand an approach to base training that doesn’t involve adhering to strict rules. There are three principles.

First, do most of your running easily, below AeT. If you take nothing else away from this article, have it be that. All year, most of your training should be below AeT, and during a base period, a bit more than most. You can get lab tested if you want to dial it in or use the MAF calculation if you want a very rough approximation. You can also use some field testing that provides a rough-but-individualized approximation (I prefer an adaptation of the Friel Method, doing a 30-minute hard time trial, taking the average heart rate from the last 20 minutes and multiplying that by around 0.80 to 0.85 for a general feel for AeT, adjusting based on how it feels). But ideally those things just act as spot-checks to calibrate that what you perceive as easy is actually easy.

Second, develop top-end sustainable speed after AeT feels efficient. One way might be to do four to eight hill strides and/or flat strides around the fastest you can go without sprinting for 15 to 30 seconds one to three times per week during a normal easy run. That alone may be enough to get a positive feedback loop going between aerobic development and neuromuscular development.

Third, for advanced athletes, add in some relaxed progression runs to steady effort occasionally when things feel good. Don’t go hard though. There’s no need to force it in base periods, and don’t race these.

Putting it all together, you probably don’t need to be dogmatic about your base period of aerobic development. You won’t ruin everything if you exceed AeT. The body doesn’t adapt in barriers and thresholds, but across spectrums.

Just make sure your easy is actually easy. It’s OK to really go slow. It’s also OK to go a bit faster when things feel good. And it’s often very important to continually practice the mechanics of speed even if you’re not seeking upper-end adaptations to intense stimuli.

Go slow to get fast. But make sure you occasionally go fast to avoid getting slow.

David Roche partners with runners of all abilities through his coaching service, Some Work, All Play. His book, The Happy Runner, is about moving toward unconditional self-acceptance in a running life, and it’s available now on Amazon.