The MicroCast

Lactic acid, static stretching, stability shoes, heel striking, 180 cadence, and icing everything: some running advice has not held up. Coaches Zoë Rom and TJ David cover six common myths, what the research actually shows, and why some of these ideas have stuck around for so long. Zoë also apologizes to everyone she sold motion-control shoes to in Northwest Arkansas.

Also in this episode:

• A listener asks why they feel wired and c...

Ready for your next ultra distance? Maybe. In this episode, we tackle the question of when to move up from the 50K to the 50 mile, 100K, 100 mile, and beyond, and why the "ladder" framing might be steering you wrong. Distance alone doesn't say much about what a race demands. A mountainous 50K can ask more of you than a runnable 50 miler, so we talk about how to size up a race by duration, terrain, and your own capacity.

We start wit...

Zoë's article on Ability vs. Ambition

YDS Episode on "Racing Weight"

There's always a gap between where you are as an athlete and where you want to be. Zoë wrote about it for UltraSignup , "Closing the Gap Between Ability and Ambition", and this week TJ reads it back to her, days before she lines up at Run Rabbit Run 100 for the third time. They dig into Ira Glass's idea of "the gap," why admitting you want to be great feels so vulne...

How many miles a week do you need to run to get better? It's the question coaches hear most, and the annoying answer is: enough to create an adaptation, not so much that you can't absorb it. The body doesn't experience a mileage total. A mile on a 14er and a mile on a track are completely different stresses, which is why time at effort is a better way to think about volume than distance.

TJ and Zoë break volume into four levers. How...

Leadville 100 week gave Microcosm both ends of the sport in a single day: coach TJ David's athlete McKendree Hickory won the women's race in her 100-mile debut, and TJ himself dropped at the Winfield turnaround after nearly fifty miles of not being able to breathe.

Zoë and TJ take both apart honestly. On the win: what five months of coaching actually changed, why TJ inferred McKendree was naturally durable from four years of trainin...

Your easy pace is slower than it was two months ago. Workouts feel harder. You're doing more volume than you've ever done — so shouldn't you be getting faster?

A listener wrote in with exactly that question, and it turned into a full episode. Coach TJ and Zoë unpack why feeling slower in a big block is usually the block working, not the block failing — and how to tell the difference when it isn't.

The core idea: fitness a...

Email us your listener questions or hot or nots at microcosmcoaching@gmail.com.

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Downhill running is a technical skill, not a fitness problem, and this week Zoë Rom and TJ David break down the science of eccentric loading, the repeat bout effect, and how to descend faster without trashing your quads.

They go inside the muscle to explain what actually happens to your sarcomeres on a long de...

Recovery is the ceiling on your training — not your mileage, not your workout schedule. Zoë Rom and TJ David break down the five places recovery falls apart for endurance athletes: not sleeping enough, chronic underfueling, easy days that drift into the gray zone, treating life stress like it doesn't count as training stress, and never taking a real down week. They walk through the physiology of why fitness is actually built ...

ou've built the fitness. Now what? This week we're digging into training specificity: how to shape your training around the actual demands of your goal race, whether that's a road marathon, a 50K, or a 100-miler like Leadville or Hardrock. Specificity is the sexy stuff athletes love to obsess over, but it's also where we see the most expensive mistakes. We break down what race-specific training actually means, when it belongs in yo...

What is fitness, really? VO2 max, lactate threshold, running economy, durability, and neuromuscular power — in this episode we break down the five distinct systems hiding inside that one word, how each one develops, which respond fastest to training, and which age best. If you've ever chased a watch number and wondered why your race results didn't follow, this framework explains why "getting fitter" is actually five separate ...

Heat training and altitude training are two of the most obsessed-over (and most misunderstood) tools in endurance running. In this episode, Zoë and TJ break down the actual science: what heat adaptation does to your blood plasma, why "poor man's altitude" is a myth, and how the EPO-to-hemoglobin response really works up high.

They cover who should bother with heat or altitude training at all, the two questions to ask before you sta...

Durability is the word every endurance runner has latched onto — but what actually is it, and how do you build it? Zoë and TJ break down durability for marathon and ultra runners: the difference between aerobic durability (heart rate drift and cardiac decoupling over long efforts) and mechanical durability (the eccentric loading that blows up your quads on late-race descents), why a smaller engine that doesn't fade beats a bi...

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AI vs. human coaching is the big question this week: can a chatbot really build your training plan, or is it a premium cookie cutter? Zoë and TJ break down what coaching actually is — the plan plus the relationship, communication, and buy-in that no model replicates — and dig into...

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Long runs, ultramarath...

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How do you know if your training, supplements, or recovery hacks are actually working — or if you're just fooling yourself? Zoë and TJ break down the science of the N of 1 experiment and how to self-coach intelligently in a world flooded with biohacks, miracle protocols, and "th...

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Running metrics, wearables, and training data get a reality check this week as Zoë and Kylee Van Horn cut through the noise of HRV scores, readiness ratings, and AI coaches to name the five numbers that actually move the needle in 2026. The episode opens with a familiar character: the athlete double-fisting a Whoop and a Garmin who hasn't strung four consistent weeks of training togethe...

Running economy is one of the most misunderstood concepts in endurance training — and one of the most trainable. In this episode, Zoë Rom and TJ David break down what running economy actually is, why it matters more than VO2 max for marathoners and ultra runners, and the specific levers you can pull to get more output for the same input. Using the analogy of miles per gallon, they explain how two runners with identical VO2 m...

Hydration is one of the most overlooked levers in endurance performance — and one of the most punishing when you get it wrong. In this episode, Zoë and TJ unpack why dehydration is so much more than feeling thirsty, walking through the cascading downstream effects on your gut, your blood, your muscles, and ultimately your race result. They cover gut osmolality and why a too-concentrated drink mix actually pulls water the wron...

This week we welcome you behind the scenes of Microcosm Coaching with a quick introduction to Coach Zachary Russell, an athletic trainer and strength coach whose multisport background spans Ironman, triathlon, marathoning, and trail running. He shares what kinds of athletes light him up to coach and how his experience across disciplines shapes the way he builds plans.

Then Zoë and TJ dig into TJ's recent Canyons Endurance Run 100K, ...