Running in the lab versus running in the real world: why they differ and what to do about it

My article from a few weeks ago on Emile Cairess’ training before his 3rd-place finish at this year’s London Marathon was one of the most popular articles I’ve written in a long time. However, it actually wasn’t the only article I published that week! A few days prior, one of my dissertation studies was published, and it was titled:

Are Gait Patterns during In-Lab Running Representative of Gait Patterns during Real-World Training?”—and the answer is “not really.”

I’d like to go over both what we did in this study and what implications it has for people (like me!) who want to apply findings from biomechanics research to real-world training.

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Getting the interval workout recovery right

I’ve previously written about getting the warm-up right and getting the cool-down right. Getting these components of training right is a relatively minor component of the design of an overall training program.

Still, if you’re planning on having a long running career (or if you’re a coach working with a team), you’re going to be doing a lot of warm-ups, cool-downs, and recovery intervals. So, it’s worth spending a bit of time to make sure you’re getting them right.

When it comes to the recovery during interval workouts, you’ve got three variables to optimize:

  • How much recovery to take
  • How you measure your recovery (i.e. as time vs. as distance)
  • What to do during the recovery interval (e.g. stand, walk, jog, or run—and how fast)

Like in my cool-down article, I think it is useful to frame these questions in terms of who is doing the workout, what kind of workout they are doing, and what your training goals are, both for that workout and for the training cycle overall.

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Modern marathoning with Renato Canova: Analysis of Emile Cairess’ training before the London Marathon

Marathoner Emile Cairess, coached by Renato Canova

Renato Canova is one of the greatest coaches in all of athletics: his runners have won global medals and set records at distances from the 800m to the marathon.

Canova’s training methods have their roots in the “Italian School” of training that developed during the 1980s and 1990s. Canova later refined his training approach through his work with top Kenyan and Ethiopian runners in the 2000s.

Today, he works with top athletes from all over the world, including runners from Germany, Norway, Switzerland, Kenya, and, pertinent to the topic of this article, the United Kingdom.

Canova-coached marathoner Emile Cairess, a 26-year-old from northern England, had an extraordinary season this spring, clocking 60:01 at the Naples Half Marathon in February and 2:06:46 for third place at the London Marathon in April. He is now the second-fastest UK marathoner ever, second only to Mo Farah.

Cairess’ short-distance PRs are good (13:26 for 5k and 27:34 for 10k) but not incredible—24 Americans ran faster than his 5k PR in 2023 alone. So, how does a young, talented 5k/10k runner become the second-fastest marathoner in UK history?

Well, we don’t have to speculate—Renato Canova posted his full training schedule for the 16 weeks leading up to London!

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The science of running in super spikes: New data on Nike, Adidas, and PUMA track shoes

Lab scientist holding a prototype track and field super spike

Super spikes are track spikes for middle and long distance events that use the two key innovations in shoe tech that have revolutionized marathon shoes: “super foam” with high deformation and excellent energy return, and carbon fiber plates in the midsole.

I have a longer and more detailed article in the works that takes a deep dive into the biomechanics of super shoes more generally, but I wanted to get this post out since it’s track season and people want to run fast!

The impetus for this post was a fascinating new preprint on the benefits of super spikes from a multi-site collaboration involving research labs in Spain, the US, and Canada. The focus of the study is middle distance performance in super spikes versus traditional spikes.

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Is VO2max correlated with running performance?

Artistic scatterplot showing 3k race times as a function of VO2max

Quite often I hear people claiming that “VO2max is not correlated with running performance.” Is that true?

What about similar correlation-based claims about metrics like body composition, running economy, mileage, and maximum heart rate?

Usually, when people make these kinds of claims, they link to a study showing that, among a certain group of runners, the metric in question (e.g. VO2max) does not accurately distinguish between the fastest and slowest runners in the group.

Another version of these claims comes in the form of statements like “among runners with a similar VO2max, those with better (running economy / lactate threshold / some other performance metric) have faster race times.”

So, what should we make of these kinds of claims? My goal in this article is to show why correlations will always become weaker when you restrict your analysis to a small subset of a population, like elite athletes.

Let's dig in and see why.

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Iron supplements, ferritin levels, and VO2max gains in athletes

Red blood cells in the style of a hand-drawn sketch

There’s a new study out this month on iron supplements for athletes with low ferritin. The study, published by Anja Neža Šmid and colleagues at the University of Ljubljana in Slovenia, is a meta-analysis, meaning it pooled data from several different randomized trials that took athletes, assigned them to either a placebo group or an iron supplement group, then measured the difference in ferritin levels between groups after the study’s conclusion.

The results of this meta-analysis are some of the strongest evidence that I’ve seen that support the notion that athletes with ferritin levels circa 20 ng/mL will benefit from an iron supplement. However, I wanted to write up this post because that’s actually not how the authors of the study interpret their own results!

Here’s what Smid et al. say in the abstract:

Increase in serum ferritin concentration after [oral iron supplementation] was evident in subjects with initial pre-supplementation serum ferritin concentration ≤12 µg/l [ ng/mL], while only minimal, if any effect, was observed in subjects with higher pre-supplementation serum ferritin concentration.

Šmid et al 2024

How can I justify the benefits of iron supplementation at 20 ng/mL, while the authors cite a cut-off value of barely half that level? Well, it all comes down to the way you analyze the data.

Here’s the bottom line up front: when treating ferritin level as a continuous number—which it is—the study’s data clearly show that runners with ferritin levels of around 20 ng/mL or less will experience significant increases in ferritin and gains in VO2max when taking an iron supplement over the course of 6–8 weeks.

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Problems with the critical speed model: Can power laws predict running performance better?

Digital art image of a runner with math equations in the background

The critical speed model—also known as critical velocity, CV, or critical power—is a powerful concept for understanding what running speeds are sustainable at a metabolic steady-state and what speeds are not.

Critical speed is not without its detractors, though, and the critical speed model is certainly not without its flaws.

I just posted a huge article on understanding the science of critical speed, critical velocity, and critical power for runners. That article goes in-depth on what critical speed is, how the model works, and how you can use it in your training.

I was originally planning on including the major criticisms of critical speed as a part of that article, but it’s long enough as it is.

So here, separately, is a summary and analysis of the main problems with critical speed (and, by extension, critical power) as a model for endurance performance, plus some rejoinders as to why alternative models, like the power law model of performance, are not always better.

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The science of critical speed, critical velocity (CV), and critical power training for runners

Female athlete running in front of scientific graphic paper

Critical speed is the boundary that separates running speeds that can be sustained at a metabolic steady-state from speeds that cannot. Sometimes called critical velocity or “CV,” critical speed is known in the running world in partly due to its popularization by Tom “Tinman” Schwartz and his proteges, including Drew Hunter.[1]

Critical speed is increasingly becoming the gold standard among physiologists for identifying the limit of what runners would call “high-end aerobic” or “steady-state” running speeds, and is gaining traction as a training tool as well. The critical speed model explains the body’s response to different speeds better than older models based on the lactate threshold.

Among exercise physiologists, critical speed (or a semi-related concept, the maximum lactate steady state, which we’ll also discuss) is rapidly becoming the gold standard for capturing the aerobic fitness of athletes.

Critical speed has its roots in early work in the 1960s, 70s, and 80s, but didn’t really start to emerge as the strongest physiological model for intense exercise until the last 15 years or so.

In this article, we’ll take a detailed look at the critical speed phenomenon, understand how it works on a mathematical and physiological level, see some of the problems and controversies surrounding it, and learn how to apply the concept of critical speed in your own training.

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A comprehensive overview of Canova-style percentage-based training for runners

Percentage-based training is a mathematical approach to planning workouts for runners. Percentage-based methods are used by many top international coaches, most notably Renato Canova, to train runners at distances from 800m to the marathon. 

I could write a whole book about percentage-based training for runners (in fact, maybe I will someday), but the goal of this post is to give a clear, comprehensive, and readable overview of percentage-based training as a system—a set of principles that can be used to guide training decisions.

To this end, we’re going to focus on the concepts and rationale behind the percentage-based training method, as opposed to exact training calendars. This post does include an appendix with recommended workouts for every event from 800m to the marathon (even the 3k!), but event-specific full training calendars will be a project for another day.

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Did you know I have a book? Check it out here!