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.

  1. 3 days ago

    Episode 26 - The fitness that survives: How to Build Durability for 100K and 100-Mile Races

    Durability is the ability to preserve your performance as fatigue accumulates during prolonged exercise. While fitness describes what you can do when fresh, durability determines how much of that fitness remains after many hours of running. In a 100K or 100-mile race, pace can decline because of muscular damage, worsening running economy, reduced force production, poor fuelling and mental fatigue. A durable runner still becomes tired, but their deterioration is slower and more manageable. Durability is developed through consistent training volume, progressive long runs, selective back-to-back sessions, race-specific terrain, downhill conditioning and strength training. Long runs should also be used to practise realistic pacing, hiking, nutrition and equipment. The common mistake is trying to prove durability through excessively long or exhausting sessions. Durability is not built by destroying the body in one weekend. It comes from months of sustainable training that can be repeated consistently. Fitness may carry you through the first half of an ultra. Durability determines what remains for the second.Key References: Maunder, E., Seiler, S., Mildenhall, M. J., Kilding, A. E., & Plews, D. J. (2021). The Importance of “Durability” in the Physiological Profiling of Endurance Athletes. Sports Medicine, 51, 1619–1628. DOI: 10.1007/s40279-021-01459-0. Jones, A. M. (2024). The Fourth Dimension: Physiological Resilience as an Independent Determinant of Endurance Exercise Performance. The Journal of Physiology, 602, 4113–4128. DOI: 10.1113/JP284205. Millet, G. Y. (2011). Can Neuromuscular Fatigue Explain Running Strategies and Performance in Ultra-Marathons? The Flush Model. Sports Medicine, 41, 489–506. DOI: 10.2165/11588760-000000000-00000. Millet, G. Y., Tomazin, K., Verges, S., et al. (2011). Neuromuscular Consequences of an Extreme Mountain Ultra-Marathon. PLOS ONE, 6, e17059. DOI: 10.1371/journal.pone.0017059. Tanda, G., & Knechtle, B. (2015). Effects of Training and Anthropometric Factors on Marathon and 100 km Ultramarathon Race Performance. Open Access Journal of Sports Medicine, 6, 129–136. DOI: 10.2147/OAJSM.S80637. Bontemps, B., Vercruyssen, F., Gruet, M., & Louis, J. (2020). Downhill Running: What Are the Effects and How Can We Adapt? A Narrative Review. Sports Medicine, 50, 2083–2110. DOI: 10.1007/s40279-020-01355-z. Llanos-Lagos, C., Ramírez-Campillo, R., Moran, J., & Sáez de Villarreal, E. (2024). Effect of Strength Training Programs in Middle- and Long-Distance Runners’ Economy at Different Running Speeds: A Systematic Review with Meta-analysis. Sports Medicine, 54, 895–932. DOI: 10.1007/s40279-023-01978-y. Knechtle, B., & Nikolaidis, P. T. (2018). Physiology and Pathophysiology in Ultra-Marathon Running. Frontiers in Physiology, 9, 634. DOI: 10.3389/fphys.2018.00634. Clark, I. E., Vanhatalo, A., Thompson, C., et al. (2019). Dynamics of the Power-Duration Relationship During Prolonged Endurance Exercise and Influence of Carbohydrate Ingestion. Journal of Applied Physiology, 127, 726–736. DOI: 10.1152/japplphysiol.00207.2019.

  2. 10 Jul

    Episode 25 - Carb Loading: Don’t Start Empty

    In this episode, we cover why carb loading is not about eating a huge bowl of pasta the night before a race, but about arriving at the start line with full fuel stores. For trail and ultra runners, glycogen is the body’s fast-access fuel, and starting underfuelled can make the later stages of a race much harder. The key message is simple: carb loading should be planned, practised, and spread across the final 24–48 hours before race day. A good target for long endurance events is often around 8–12 grams of carbohydrate per kilogram of body weight per day, depending on the runner, the race, and gut tolerance. The episode also explains what runners often get wrong: relying on one big meal, eating too much fibre or fat, trying new foods, or worrying about small increases in body weight caused by glycogen and water storage. The practical advice is to use familiar, easy-to-digest carbohydrate foods, reduce gut stress before race day, and rehearse the strategy before key long runs or lower-priority races. Main takeaway: Carb loading fills the tank before the race; race fuelling keeps topping it up. You cannot fully compensate during the race for arriving underfuelled. Key references: Thomas, D. T., Erdman, K. A., & Burke, L. M. — “Nutrition and Athletic Performance.” Burke, L. M., Hawley, J. A., Wong, S. H. S., & Jeukendrup, A. E. — “Carbohydrates for training and competition.” Wallis, G. A. — “Dietary Carbohydrate and the Endurance Athlete: Contemporary Perspectives.” Vitale, K., & Getzin, A. — “Nutrition and Supplement Update for the Endurance Athlete.” Kerksick, C. M. et al. — “International Society of Sports Nutrition Position Stand: Nutrient Timing.” Mata, F. et al. — “Carbohydrate Availability and Physical Performance.” Naderi, A. et al. — “Carbohydrates and Endurance Exercise: A Narrative Review.” Thomas / ACSM position statement — race-day fuelling section

  3. 3 Jul

    Episode 24 - The Low Point Is Not the End: How to Survive the Dark Miles

    In this episode, we look at one of the most important skills in ultrarunning: managing the low points. Every runner will face dark moments during an ultra, but a low point is not necessarily the end of the race. It is usually information: you may need fuel, fluids, sodium, cooling, warmer clothing, slower pacing, or simply a mental reset. The key message is: do not make big decisions from a low point. Instead, use the simple process: Check. Fix. Wait. Check what may be causing the problem, fix one or two obvious things, then give yourself 15 to 30 minutes before judging the race again. The goal is not to feel good all day. The goal is to stay functional when things feel bad. Key references: Pageaux, B. - “The psychobiological model of endurance performance” Marcora et al. - “Mental fatigue impairs physical performance in humans” Blanchfield et al. - “Talking yourself out of exhaustion: the effects of self-talk on endurance performance” Burgum et al. - “Reduced mood variability is associated with enhanced performance in ultramarathon running” Bieleke et al. - “If-then planning” Tiller et al. - “International Society of Sports Nutrition Position Stand: Nutritional considerations for single-stage ultra-marathon training and racing” Hew-Butler et al. - “Exercise-Associated Hyponatremia: 2017 Update” Cao et al. - “Head, face and neck cooling as per-cooling during exercise in the heat” Bongers et al. - “Cooling interventions for athletes” Costa et al. - “Nutrition for Ultramarathon Running: Trail, Track, and Road”

  4. 26 Jun

    Episode 23 - Heat Acclimation: Train the Body Before the Weather Tests You

    In this episode, we explain the difference between heat acclimatisation and heat acclimation. Acclimatisation usually refers to adapting naturally to a hot environment, while acclimation is a more controlled process using tools like hot-water immersion, sauna, or structured heat exposure. The key message is that heat adaptation is not just about “getting used to suffering.” It creates real physiological changes: lower heart rate at a given pace, earlier and more efficient sweating, better temperature regulation, reduced perceived effort, and improved tolerance when racing or training in warm conditions. For ultrarunners, this matters because heat can compromise pacing, hydration, fuelling, digestion, decision-making, and overall race performance. However, heat work should be treated as training stress, not recovery. The episode gives practical starting points for both hot-water immersion and sauna: begin with short exposures of 10–15 minutes after easy runs, then gradually build towards 20–30 minutes, and only progress further if well tolerated. It also highlights precautions: avoid heat exposure when ill, dehydrated, dizzy, very fatigued, or medically vulnerable. The main takeaway: do not wait until race day to discover how your body responds to heat. Train the heat response before the weather tests you. Key references: Racinais et al. 2015 — Consensus Recommendations on Training and Competing in the Heat Racinais et al. 2023 — IOC Consensus Statement on Recommendations and Regulations for Sport Events in the Heat Zurawlew et al. 2018 — Post-exercise Hot Water Immersion as a Practical Heat Acclimation Strategy Zurawlew et al. 2019 — Hot Water Immersion, Retention of Heat Adaptations Scoon et al. 2007 — Post-exercise Sauna Bathing and Endurance Performance in Competitive Runners Casa et al. 2015 — National Athletic Trainers’ Association Position Statement: Exertional Heat Illnesses Roberts et al. 2021/2023 — ACSM Expert Consensus Statement on Exertional Heat Illness

  5. 19 Jun

    Episode 22 - The Minimum Intensity for the Right Adaptation. No More.

    In this episode, we explore one of the most important principles for sustainable ultrarunning progress: using the minimum intensity needed to create the right adaptation. The goal of training is not to suffer as much as possible. The goal is to apply the right stimulus, recover from it, and repeat it consistently over time. Whether we are doing intervals, hill work, downhill sessions, strength training, or long runs, the same principle applies: enough stress to adapt, but not so much that it disrupts the rest of the training block. The episode compares training intensity with a doctor prescribing medication. The best dose is not the highest dose; it is the dose that works with the fewest side effects. In running, too much intensity can create unnecessary fatigue, soreness, injury risk, and poor recovery. Too little does not create adaptation. The sweet spot is the smallest useful dose. For ultrarunners, this means progressing gradually, respecting recovery, and judging sessions not only by how hard they feel, but by whether they allow consistent training afterwards. Key message: Train hard enough to adapt, but not so hard that the cost is greater than the benefit. Key references: Androulakis-Korakakis et al. — The Minimum Effective Training Dose Required to Increase 1RM Strength in Resistance-Trained Men Schoenfeld et al. — Resistance Training Volume Enhances Muscle Hypertrophy but Not Strength in Trained Men Hughes et al. — Adaptations to Endurance and Strength Training Spiering et al. — Maintaining Physical Performance: The Minimal Dose of Exercise Needed to Preserve Endurance and Strength Over Time Rosenblat et al. — Polarized vs Threshold Training: Systematic Review and Meta-analysis Muñoz et al. — Does Polarized Training Improve Performance in Recreational Runners? Oliveira et al. — Comparison of Polarized Versus Other Types of Endurance Training Intensity Distribution Tallis et al. — Repeated Bout Effect of Downhill Running on Physiological Markers and Muscle Soreness Assumpção et al. — A Single Bout of Downhill Running Attenuates Subsequent Exercise-Induced Muscle Damage Martinez-Navarro et al. — Downhill Running-Induced Muscle Damage in Trail Runners

  6. 12 Jun

    Episode 21 - Why Elites Descend Faster With Less Damage

    Elite trail runners do not descend faster simply because they are braver. They descend faster because they brake less. Downhill running creates a lot of muscle damage because the quadriceps are working eccentrically: they produce force while lengthening to control the body against gravity. Every downhill step is like a small controlled landing. When runners overstride, lean back, tense up, and land heavily, the quads act like emergency brakes. This feels safer in the moment, but over a long race it destroys the legs. Elites are better because they descend with more rhythm, better posture, quicker steps, and less unnecessary braking. Their feet land closer under the body, their upper body stays relaxed, and they read the terrain earlier. This allows them to move faster while creating less damage. The practical message is that downhill running must be trained gradually. Start with short, controlled downhill efforts, focus on light feet and quick cadence, then build towards longer descents and descending on tired legs. Strength work also helps, especially controlled eccentric exercises like step-downs, split squats, lunges, and slow squats. Main takeaway: Do not train downhill just to prove toughness. Train downhill to reduce the cost of descending. The best descent is not the one where you feel heroic at the top; it is the one that leaves you with legs at the bottom. Key references: Bontemps, B. et al. (2020). Downhill Running: What Are The Effects and How Can We Adapt? A Narrative Review. Sports Medicine. Bontemps, B. et al. (2020). Full-text review via PMC. Tallis, J. et al. (2024). Repeated Bout Effect of Downhill Running on Physiological Markers of Effort and Post-Exercise Perception of Soreness in Trained Female Distance Runners. Sports. Coratella, G. et al. (2024). Downhill running increases markers of muscle damage and alters jump performance. Martínez-Navarro, I. et al. (2026). Downhill Running-Induced Muscle Damage in Trail Runners: An Exploratory Study Regarding Training Background and Running Gait. Sports. Genitrini, M. et al. (2022). Downhill Sections Are Crucial for Performance in Trail Running.

  7. 5 Jun

    Episode 20 - Caffeine for Ultrarunners. Don’t Take More, Take It Smarter

    Caffeine is one of the most evidence-supported supplements for endurance performance, but ultrarunners need to use it strategically rather than simply taking more. The key message is that caffeine is not fuel. Carbohydrates provide energy for the muscles; caffeine mainly helps with alertness, focus, motivation, and perceived effort. This makes it especially useful in long ultras, where mental fatigue, sleepiness, low mood, and poor decision-making can become as limiting as physical fatigue. For shorter races, caffeine before the start can be useful. But in longer ultras, especially races lasting over 8–15 hours or through the night, it is often better to delay caffeine until the second half, the night section, or the final third, when its benefits are more valuable. A practical starting point is 25–50 mg per hour once caffeine use begins, adjusted based on tolerance. Some runners may tolerate more, but higher doses increase the risk of stomach issues, anxiety, jitters, and sleep disruption. The episode emphasises that caffeine should never replace proper fuelling. When energy drops, the first question should be: have I taken enough carbohydrates? Main takeaway: Fuel with carbohydrates. Focus with caffeine. Caffeine is not the engine; it is the light you switch on when the road gets dark. Key references: Guest, N. S. et al. (2021). International Society of Sports Nutrition Position Stand: Caffeine and Exercise Performance. Journal of the International Society of Sports Nutrition. Australian Institute of Sport. Caffeine: Performance Supplement Guide. Wang, Z. et al. (2022). Effects of Caffeine Intake on Endurance Running Performance and Time to Exhaustion: A Systematic Review and Meta-analysis. Nutrients. Shen, J. G. et al. (2019). Establishing a relationship between the effect of caffeine and duration of endurance athletic time trial events. Journal of Science and Medicine in Sport.Goldstein, E. R. et al. (2010). International Society of Sports Nutrition Position Stand: Caffeine and Performance. Journal of the International Society of Sports Nutrition. Benchetrit, S. et al. (2024). The effects of sleep deprivation and extreme exertion on cognitive performance in ultra-marathon runners. Martinez Gonzalez, B. (2022). Sleep Deprivation and Ultra-endurance Performance. University of Kent thesis. Office of Dietary Supplements, NIH. Dietary Supplements for Exercise and Athletic Performance: Health Professional Fact Sheet.

  8. 29 May

    Episode 19 - Why Your Legs Die Before Your Lungs

    In this episode, we explore why many trail and ultra runners feel that their breathing is still under control, but their legs simply stop working. The main idea is that ultra running is not limited only by cardiovascular fitness. It is also limited by local muscular endurance: the ability of the quads, calves, glutes and stabilising muscles to keep producing force for hours. Climbing, descending and technical terrain all place specific demands on the legs. Uphills require repeated force production, downhills create muscle damage through braking and impact, and trails constantly challenge stability and control. This is why a runner can still have a strong aerobic engine but lose performance when the legs are no longer able to absorb, stabilise and push. The episode explains that the solution is not simply more mileage. Runners need race-specific preparation: uphill muscular endurance, downhill conditioning, purposeful hiking, and consistent strength training. Key message: Train the engine, but build the chassis. In ultras, strong legs protect good fitness. Key references: Millet et al. 2011 — neuromuscular fatigue in mountain ultras.Bontemps et al. 2020 — downhill running and eccentric damage. Pradas et al. 2021 — ultratrail racing, muscle damage and neuromuscular function. Balsalobre-Fernández et al. 2016 — strength training and running economy. Llanos-Lagos et al. 2024 — updated systematic review on strength training and running economy.

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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
    2026
  • Episodes
    26
  • Rating
    Clean
  • Copyright
    © Coach Isaac Alcaide
  • Show Website
    The Trail Running Briefing

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