The MicroCast

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...

🏃 Microcosm Open House — Wednesday, June 11th at 5:30pm MT (virtual). Meet the coaches, ask anything, no pressure. Sign up: https://docs.google.com/forms/d/e/1FAIpQLSc0KnmFGBxZNYqTAZDNFSRUL86UXK7gCIVDDlLtWJBp5WoVvQ/viewform?usp=header

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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, ...

Why does your running fitness plateau, and what can you actually do about it? Zoë and TJ break down the five real reasons endurance athletes get stuck, a lack of training intentionality, under-recovery, chronic under-fueling, a mismatch between training and event demands, and failing to apply progressive overload across more than one lever.

This episode also features a coach spotlight with James Nance, a Microcosm coach specializin...

Most runners follow a training plan. Very few understand the architecture behind why it's built the way it's built, and that gap is exactly where progress stalls.

This week, we break down the science of periodization: what it actually is, how to structure a full training year around it, and the most common mistakes that keep athletes stuck in the gray zone. We cover training intensity distribution (pyramidal vs. polarized vs. mixed...

Most runners ask one question before a race: did I finish my training plan? But fitness and race readiness are not the same thing — and in this episode, Zoë and TJ break down the physiological and psychological framework that actually tells you whether you're ready to toe the line.

They start with the foundational model: fitness + freshness + specificity. Using the Banister fitness-fatigue model, they explain how both signals ...

Zoë and TJ are back from Italy and kicking off April with a packed episode. First up: coach Kyle Jones: a masters athlete and ultra running specialist with a focus on helping athletes who are all in on the long game, whether that's accumulating volume safely or solving the full puzzle of race-day logistics that go far beyond training.

Then it's Hot or Nots. On the docket: incline stretch boards for calf and Achilles work (the eviden...

If you've ever thought "I'm not dieting, I'm optimizing", this episode is for you.

We're dropping this one from the Your Diet Sucks vault because we think it belongs in the feed of every endurance athlete. We brought in coach TJ David, former professional skier and elite endurance athlete, and Sean Van Horn, elite athlete, Kylee Van Horn's husband, and someone who spent six years not telling a single person he was struggling, becaus...

Meet coach Kyle Jones, a master's athlete dedicated to helping other runners achieve their biggest goals, no matter their age. See more and book a free consultation call at microcosm-coaching.com.

Every few months, a new training idea goes viral, and suddenly it's everywhere. Zone 2. Cycle syncing. Ketones. Heat suits. Ninety grams of carbs an hour. The science behind most of these things is real. That's not the problem. The problem...

Running twice a day sounds serious, but is it actually right for you? This week, Zoë and TJ dig into the full science of doubles: what they are, what they're definitively not, and how to know if you're actually a candidate. Plus, a round of listener-submitted Hot or Nots and a great question about why early morning runs feel so much harder.

First up, meet Coach James Nance, a multi-sport specialist who coaches cyclists, runners, and...