The MicroCast

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 "...

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 trainin...

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...

Sign up for our open house here! https://docs.google.com/forms/d/e/1FAIpQLSc0KnmFGBxZNYqTAZDNFSRUL86UXK7gCIVDDlLtWJBp5WoVvQ/viewform?usp=header 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...

🏃 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 💪 Want coaching without the full 1:1 commitment? Join Foothills for twice-monthly Ask the Coaches sessions — $10/month with code Foothills10 at microcosmcoaching.c...

Sign up for our free open house here! (https://docs.google.com/forms/d/e/1FAIpQLSc0KnmFGBxZNYqTAZDNFSRUL86UXK7gCIVDDlLtWJBp5WoVvQ/viewform?usp=header) 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 bi...

Check out the fuel tracking app here! FuelFlow 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 f...

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...

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...

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&#...

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 N...

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 dist...

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 mod...

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 b...

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 spe...

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...

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 s...

We brought in the person we trust with our own training. Cliff Pittman is the Director of Coaching at Carmichael Training Systems, which means he's essentially a coach of coaches, overseeing the education and development of CTS's entire coaching staff. He's also, full disclosure, our coach. So we wanted to have an honest conversation about what coaching actually is, what it isn't, and the massive...

Is your watch making you a worse runner? We dig into two powerful books — The Way of Excellence by Brad Stulberg and The Score by C. Thi Nguyen — to unpack how metrics, Strava segments, and training scores can quietly hijack your motivation and identity as an athlete. We also tackle a wild listener question: a 23-year-old running 30 hundred-milers a year. We break down the real physiology — rhabdo...

Wired article on the Enhanced Games: https://www.wired.com/story/enhanced-games-freestyle-record-las-vegas-steroids/ You've got a distance that sounds impossible — maybe it's a marathon, maybe it's a 100-miler. The process for preparing to go longer than you ever have is more similar across distances than you might think. TJ and Zoë break down the physiology, psychology, and practical...

Is fasted running sabotaging your performance? Are you accidentally under-eating on your hardest training days? This week, we break down the seven most common nutrition mistakes runners make, from calorie restriction at the wrong time to blindly copying elite protocols, and explain why the science says you probably need to eat more, not less. We cover why your gut issues might actually be a traini...

How do you keep training when life gets stressful? Whether you're navigating a new job, new baby, a big move, or personal loss, your body processes all stress the same way—and that changes everything about how you should train. In this episode, we break down the science of stress and running performance, including how the HPA axis works, why your "stress bucket" has a finite capacity...

Taking time off from running, whether from injury, illness, or life—doesn't have to derail your progress. In this episode, we break down the actual physiology of detraining and give you a science-backed framework for returning smarter, not just faster. We cover what happens to your body during time off (spoiler: it's not as catastrophic as your brain tells you), why connective tissue is th...

📧 ⁠microcosmcoaching@gmail.com⁠ 🌐 microcosm-coaching.com💬 Foothills Community: $10/month (code FOOTHILLS10) Does cross-training actually help runners, or is it just a distraction from the main thing? We break down the research on what transfers to running performance and what doesn't, covering AlterGs, curved treadmills, ellipticals, cycling, swimming, yoga, and Pilates. The key finding: VO2 ma...

Happy New Year! Welcome to our first episode of 2026. We kick things off with our Athens Big Fork Trail Marathon race recap—Zoe ran an 8-minute PR after 4 years of training (that's 30 miles per second of improvement), while TJ ran his worst time ever and learned some valuable lessons about mental performance and showing up when things don't go your way. Then we answer a listener question:...