The Trail Running Briefing

Coach Isaac Alcaide
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The Trail Running Briefing is a short, weekly podcast for trail runners and endurance athletes who want to train with purpose. In 5–8 minutes, each episode focuses on one specific aspect of performance: training design, physiology, strength, durability, or race execution. No hype. No filler. Just clear, practical insights you can use immediately. Hosted by Isaac Alcaide, endurance coach, the podcast is designed to be listened to on the move, during easy runs, commutes, or recovery helping you understand your training so you can run better, longer, and with more confidence on the trail.

Episodes

  1. 6 DAYS AGO

    Episode 11 - The Cost of Going Too Hard

    Training hard has its place, but harder is not always better. In this episode, we explore why the real value of a session is not just in the stimulus it provides, but in the recovery cost it creates. For trail and ultra runners, going too hard too often can quietly reduce consistency, compromise quality, increase injury risk, and leave you too fatigued to absorb the training that actually matters. The key message is simple: the best training is not the hardest training, but the training you can recover from and repeat. Key references: Seiler S. What is best practice for training intensity and duration distribution in endurance athletes? 2010.Stöggl TL, Sperlich B. The training intensity distribution among well-trained and elite endurance athletes. 2015.Sperlich B, et al. The proportional distribution of training by elite endurance athletes. 2023.Casado A, et al. Training Periodization, Methods, Intensity Distribution, and Volume in Highly Trained Endurance Athletes. 2022.Jones CM, et al. Training Load and Fatigue Marker Associations with Injury and Illness. 2016.Drew MK, Finch CF. The Relationship Between Training Load and Injury, Illness and Soreness. 2016.Gabbett TJ. The training-injury prevention paradox. 2016.Kreher JB, Schwartz JB. Overtraining Syndrome: A Practical Guide. 2012.

    10 min

  2. 27 MAR

    Episode 10 - How to Train Downhill Safely Without Wrecking Yourself

    Downhill running is one of the most damaging parts of trail racing, not because it is aerobicly hard, but because it places heavy eccentric load on the muscles, especially the quads. In this episode, we explain why downhill running creates so much soreness and fatigue, and why the solution is not to avoid it, but to train it progressively. The key idea is that downhill training should be treated like strength training for runners: small doses create adaptation, but too much too soon can disrupt the rest of your training. We cover the repeated bout effect, common mistakes runners make, and how to build downhill durability safely through controlled exposure, good technique, and eccentric strength work. The main takeaway is simple: train downhill like strength work, not like free speed. Key References: Bontemps et al. (2020), review on downhill running, muscle damage, fatigue, and adaptation. Coratella et al. (2024), downhill running increases muscle damage markers and impairs force production, with recovery taking several days. Tallis et al. (2024), repeated bout effect in downhill running in trained runners. McHugh (2003), classic review on the repeated bout effect after eccentric exercise. Calvo-Rubio et al. (2024), review of mechanisms behind the repeated bout effect. Baxter et al. (2024), once-weekly submaximal eccentric resistance training can still improve neuromuscular function.

    11 min

  3. 20 MAR

    Episode 9 - Running Fast by Slowing Down

    In this episode of The Trail Running Briefing, we explore one of the most important but misunderstood ideas in endurance training: you often run faster by slowing down more often. Many runners make the mistake of pushing too hard on easy days, turning most of their training into moderate effort and limiting recovery, consistency, and performance. This episode explains why truly easy running is essential for building aerobic fitness, supporting recovery, and preparing you to perform better in key sessions and races. The message is simple: easy runs should feel easy, and that discipline is often what leads to long-term progress. Key references: Seiler S. (2010). What is Best Practice for Training Intensity and Duration Distribution in Endurance Athletes?Esteve-Lanao J, San Juan AF, Earnest CP, Foster C, Lucia A. (2007). How Do Endurance Runners Actually Train? Relationship with Competition Performance.Stöggl T, Sperlich B. (2014). Polarized Training Has Greater Impact on Key Endurance Variables than Threshold, High Intensity, or High Volume Training.Neal CM, Hunter AM, Galloway SDR. (2013). Six Weeks of a Polarized Training-Intensity Distribution Leads to Greater Physiological and Performance Adaptations than a Threshold Model in Trained Cyclists.Rosenblat MA, Perrotta AS, Vicenzino B. (2019). Polarized vs. Threshold Training Intensity Distribution on Endurance Sport Performance: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.Casado A, González-Mohíno F, González-Ravé JM, Foster C. (2022). Training Periodization, Methods, Intensity Distribution, and Volume in Highly Trained and Elite Distance Runners: A Systematic Review.Haugen T, Sandbakk Ø, Enoksen E, Tønnessen E, Seiler S. (2022). The Training Characteristics of World-Class Distance Runners: An Integration of Scientific Literature and Results-Proven Practice.

    10 min

  4. 13 MAR

    Episode 8 - Why Zone 3 Is So Misunderstood

    In this episode of The Trail Running Briefing, we unpack why Zone 3 is one of the most misunderstood training intensities in endurance sport. Often dismissed as “junk miles” or the “grey zone,” Zone 3 is frequently criticised simply because many runners use it by accident rather than with a clear purpose. This episode explains why that view is too simplistic, especially for trail runners and masters athletes. We explore how well-structured Zone 3 work can help build strong, sustainable endurance, improve climbing-specific fitness, and develop the ability to manage lactate efficiently during harder efforts. We also look at why combining brief periods of Zone 4 with sustained Zone 3 work can be so effective. Instead of seeing lactate as just a problem, this approach helps runners understand how the body can reuse lactate as a fuel source, while avoiding the excessive mechanical stress that often comes with faster, more aggressive sessions. The key message is simple: Zone 3 is not junk when it is used deliberately. The real mistake is drifting into it too often without intent. This episode gives trail runners a practical framework for using Zone 3 wisely within a balanced training week. Key references: Brooks GA. The Science and Translation of Lactate Shuttle Theory. Cell Metabolism. 2018.Faude O, Kindermann W, Meyer T. Lactate Threshold Concepts: How Valid Are They? Sports Medicine. 2009.Seiler S. What is Best Practice for Training Intensity and Duration Distribution in Endurance Athletes? International Journal of Sports Physiology and Performance. 2010.Billat LV. Interval Training for Performance: A Scientific and Empirical Practice. Sports Medicine. 2001.

    12 min

  5. 6 MAR

    Episode 7 - Fuel Utilisation Why Pace Changes What You Burn (and Why It Matters for Ultras)

    This episode explains fuel utilisation in simple terms: your body is always using a mix of fat and carbohydrate, but the harder you run, the more you rely on carbs. The key message is that many runners don’t “blow up” because they forgot to eat, they blow up because their pace created a higher carbohydrate demand than their fueling plan could support. The episode uses a simple mental model of two fuel tanks: Fat tank = large, slower energy, supports easier efforts Carb tank = smaller, faster energy, increasingly important as intensity rises It then shows how this appears in training and racing: Easy long runs often feel manageable Harder sessions, climbs, and surges can quickly increase carb demand and lead to fatigue if under-fueled Common mistakes covered: Fueling by habit (same grams/hour for every run) Under-fueling key sessions to “train fat burning” Confusing training adaptations with race-day strategy Practical advice: Match fueling to the session goal Practice race fueling in training Use pacing as part of your fueling strategy (surging early makes fueling harder) Pace and fueling must work together: the harder the effort, the more carbohydrate you need to support it. Main takeaway Pace and fueling must work together: the harder the effort, the more carbohydrate you need to support it. Key references: Jeukendrup (2014), Sports Medicine – carbohydrate intake during exercise, dose-response, multiple transportable carbohydrates, oxidation limits and practical recommendations.Wallis & Podlogar (2022), GSSI Sports Science Exchange – contemporary carbohydrate guidance for endurance athletes (before, during, after exercise; periodized carbohydrate intake).ISSN Position Stand on Ketogenic Diets (2024) – increased fat oxidation does not necessarily translate to improved endurance performance.

    11 min

  6. 27 FEB

    Episode 6 - Why Lactate Threshold Is the Real Ultra Performance Metric

    In this episode, we unpack why lactate threshold is one of the most useful predictors of ultra performance, not because you race at threshold, but because it sets the ceiling for what “sustainable” feels like for hours. A higher threshold means your steady effort costs less energy, surges hurt less, and you drift into the red less often on climbs, headwinds, heat, and technical sections. You’ll learn a simple mental model (threshold = your red line), the three most common training mistakes (turning threshold into a weekly race, using wrong zones, living in the grey zone), and a practical weekly approach: one controlled threshold session, lots of truly easy running, plus durability work to hold effort late in long runs. The key takeaway: raise your threshold, and your “easy” pace gets faster, that’s real ultra performance. Key references: Joyner, M. J., & Coyle, E. F. (2008). Endurance exercise performance: the physiology of champions. Journal of Physiology.Bassett, D. R., & Howley, E. T. (2000). Limiting factors for maximum oxygen uptake and determinants of endurance performance. Medicine & Science in Sports & Exercise.Seiler, S. (2010). What is best practice for training intensity and duration distribution in endurance athletes? International Journal of Sports Physiology and Performance.Stöggl, T., & Sperlich, B. (2015). Polarized training has greater impact on key endurance variables than threshold or high-intensity training. Frontiers in Physiology.Brooks, G. A. (2020). The lactate shuttle theory. Cell Metabolism.San Millán, I., & Brooks, G. A. (2018). Assessment of metabolic flexibility and its role in performance. Sports Medicine.Vanhatalo, A., Jones, A. M., & Burnley, M. (2011). Application of critical power in endurance sport.Training for the Uphill Athlete – Johnston, S., House, S., & Jornet, K.Endure – Alex HutchinsonScience of Ultra – multiple episodes on durability, fueling, and pacing.

    10 min

  7. 20 FEB

    Episode 5 - Why Consistency Beats Motivation

    Motivation is a mood, it comes and goes. Consistency is a system, it keeps you training even when life gets messy. This episode explains why relying on “feeling like it” leads to stop-start training, and why the runners who improve most are the ones who reduce friction, pre-decide their sessions, and protect a minimum standard on low-energy days. You’ll learn practical tools like a “minimum viable run” (short, easy, just show up), “if–then” plans for busy or bad-weather days, and simple habits that make starting easier. The key takeaway: don’t build your plan for your best days, build it for your worst week. Key references: BJ Fogg (2009), A Behavior Model for Persuasive Design (Fogg Behavior Model: motivation + ability + prompt).Habit formation systematic review/meta-analysis (time-to-habit varies; habits can start forming within ~2 months).Peter M. Gollwitzer — implementation intentions (“if–then” planning).Ntoumanis et al. — Self-Determination Theory meta-analysis in health behaviors (internalized motivation supports adherence).James Clear quote on systems vs goals (popular framing for behavior systems).

    9 min

  8. 13 FEB

    Episode 4 - Why VO₂max Doesn’t Win Ultra Races

    VO₂max measures your maximum aerobic capacity, but ultra races are not performed anywhere near that intensity. What decides performance is not how big your “engine” is, but how efficiently and sustainably you can use it for many hours. Ultra success depends on factors like lactate threshold, aerobic efficiency, fueling tolerance, muscular durability (especially for long descents), and disciplined pacing. Chasing VO₂max through frequent high-intensity sessions often adds fatigue without improving race-day performance. Instead, effective ultra training prioritises sub-threshold work, long aerobic sessions, strength for resilience, and practicing nutrition under load. In ultras, the winners aren’t the runners who can go the hardest. They’re the ones who slow down the least. Key references: Joyner, M. J., & Coyle, E. F. (2008). Endurance exercise performance: the physiology of champions. Journal of Physiology.Bassett, D. R., & Howley, E. T. (2000). Limiting factors for maximum oxygen uptake and endurance performance. Medicine & Science in Sports & Exercise.Seiler, S. (2010). What is best practice for training intensity distribution in endurance athletes? International Journal of Sports Physiology and Performance.Stöggl, T., & Sperlich, B. (2015). Polarized training improves endurance performance variables. Frontiers in Physiology.Brooks, G. A. (2020). The lactate shuttle theory. Cell Metabolism.San Millán, I., & Brooks, G. A. (2018). Metabolic flexibility and performance. Sports Medicine.Vanhatalo, A., Jones, A. M., & Burnley, M. (2011). Critical power: a key concept in endurance performance.

    5 min

  9. 6 FEB

    Episode 3 - Why intensity works… until it doesn’t

    Intensity can drive quick improvements in trail running performance but only for a short time. Hard sessions create a strong training signal, yet they also generate fatigue faster than they build fitness. At first, fitness gains are visible; over time, accumulated fatigue masks those gains, leaving runners feeling heavy, flat, and slower despite training harder. The mistake many runners make is responding to this fatigue by adding even more intensity or letting easy runs drift too hard. Instead, sustainable progress comes from using intensity sparingly, building a strong aerobic base, and allowing recovery to keep pace with training stress. Key message: intensity should support training, not dominate it. Rule of thumb: If intensity is always the solution, it eventually becomes the problem. Key references: The Science of Running — Steve MagnessFitness–Fatigue Model — Eric W. BanisterWhat is Best Practice for Training Intensity and Duration Distribution in Endurance Athletes? — Stephen Seiler & Espen Tønnessen (2010)Monitoring Training in Athletes with Reference to Overtraining Syndrome — Carl Foster (1998)Prevention, Diagnosis, and Treatment of the Overtraining Syndrome — Joint consensus statement (European College of Sport Science & American College of Sports Medicine)Training for the Uphill Athlete — Steve House, Scott Johnston & Kilian JornetSpecial Block Training: A Modern Approach to Endurance Training — Renato Canova

    6 min

  10. 30 JAN

    Episode 2 - Why Downhill Running Destroys So Many Ultra Races

    Most ultra runners don’t lose races on the climbs—they lose them on the descents. In this episode of The Trail Running Briefing, we break down why downhill running causes so much damage despite feeling easy at the time. You’ll learn how eccentric muscle loading silently destroys the quads, why this fatigue is delayed and deceptive, and why cardiovascular fitness alone won’t protect you late in an ultra. We also cover the most common mistakes runners make in training avoiding downhills, underestimating their impact, and treating them as free speed and what actually works instead. From smarter downhill exposure to eccentric strength work and technique adjustments, this episode gives you a simple mental model to understand why so many races fall apart after the halfway point. Key takeaway: If you don’t train your quads for the downhills, the race will. Understand your training. Run better. Key references: Eston, R., Byrne, C., & Twist, C. (2003)Muscle function after exercise-induced muscle damage and rapid adaptation.Journal of Sports SciencesChen, T. C., Lin, K. Y., Chen, H. L., Lin, M. J., & Nosaka, K. (2011)Comparison in eccentric exercise-induced muscle damage among four limb muscles.European Journal of Applied PhysiologyGiandolini, M., et al. (2016)Impact of downhill running on neuromuscular fatigue and running economy in trail runners.Journal of Applied PhysiologyVernillo, G., Giandolini, M., Edwards, W. B., Morin, J. B., Samozino, P., & Millet, G. Y. (2017)Biomechanics and physiology of uphill and downhill running in mountain races.Sports MedicineMillet, G. Y., & Lepers, R. (2004)Alterations of neuromuscular function after prolonged running, cycling and skiing exercises.Sports MedicineNicol, C., Komi, P. V., & Marconnet, P. (1991)Fatigue effects of marathon running on neuromuscular performance.Scandinavian Journal of Medicine & Science in SportsSaunders, P. U., Pyne, D. B., Telford, R. D., & Hawley, J. A. (2004)Factors affecting running economy in trained distance runners.Sports Medicine

    7 min

  11. 28 JAN

    Episode 1 - Why does your fitness drop even when you train more?

    This episode explores a common frustration among runners: increasing training volume or intensity, yet feeling slower, heavier, and less fit. The key message is simple, fitness doesn’t come from training itself, but from recovering from training. Using a clear mental model, the episode explains how training creates fatigue, and recovery is what allows adaptation and improvement. When training load increases without a matching increase in recovery, the body never fully adapts, leading to declining performance despite more effort. The briefing highlights common mistakes runners make—adding more sessions, more vert, or more intensity—while neglecting sleep, fueling, truly easy runs, and recovery weeks. It then reframes recovery as an essential part of training, not an optional extra. The episode ends with a memorable rule of thumb: You don’t get fitter by doing more. You get fitter by absorbing what you do. Key references: Meeusen, R., Duclos, M., Foster, C., et al. (2013). Prevention, diagnosis, and treatment of the overtraining syndrome: Joint consensus statement of the European College of Sport Science and the American College of Sports Medicine. European Journal of Sport Science, 13(1), 1–24. This is the strongest consensus source for the idea that overload must be balanced with adequate recovery, and that too much load plus too little recovery can reduce performance. Halson, S. L. (2014). Monitoring Training Load to Understand Fatigue in Athletes. Sports Medicine, 44(Suppl 2), S139–S147. Useful for the “fatigue can hide fitness” idea and for explaining why monitoring load and recovery matters. Foster, C. (1998). Monitoring training in athletes with reference to overtraining syndrome. Medicine & Science in Sports & Exercise, 30(7), 1164–1168. A classic paper on training stress, monotony, and the risk of performance decline when load is not managed well. Seiler, S. (2010). What is Best Practice for Training Intensity and Duration Distribution in Endurance Athletes? International Journal of Sports Physiology and Performance, 5(3), 276–291. Helpful for supporting the point that endurance performance improves when training intensity and recovery are distributed properly, not when everything becomes hard all the time. Magness, S. The Science of Running. This is a strong coaching reference for the practical explanation that training creates both fitness and fatigue, and that adaptation happens when the body is given time to respond. Hutchinson, A. Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance. Good supporting reference for the broader discussion of fatigue, limits, and why more effort does not automatically mean better performance.

    6 min
  • 11 Episodes

About

The Trail Running Briefing is a short, weekly podcast for trail runners and endurance athletes who want to train with purpose. In 5–8 minutes, each episode focuses on one specific aspect of performance: training design, physiology, strength, durability, or race execution. No hype. No filler. Just clear, practical insights you can use immediately. Hosted by Isaac Alcaide, endurance coach, the podcast is designed to be listened to on the move, during easy runs, commutes, or recovery helping you understand your training so you can run better, longer, and with more confidence on the trail.

Information

  • Creator
    Coach Isaac Alcaide
  • Years Active
    2k
  • Episodes
    11
  • Rating
    Clean
  • Copyright
    © Coach Isaac Alcaide
  • Show Website
    The Trail Running Briefing