The Trail Running Briefing

Tapering is not about resting, it’s about absorbing the training you’ve already done. After weeks or months of building fatigue through long runs and hard sessions, your body needs time to recover and convert that work into performance. Without a proper taper, you arrive at the start line carrying fatigue instead of fitness.The goal of tapering is simple: reduce fatigue while maintaining fitness. This is done by lowering overall volume (typically over 2–3 weeks for ultras) while keeping some short, controlled intensity to preserve sharpness and running economy especially important for technical trail terrain.Runners often make two key mistakes: doing too much (trying to “top up” fitness) or doing too little (losing rhythm and feeling flat). It’s also common to feel worse during the taper—heavy legs, low energy, or doubt—but this is a normal part of the process as the body shifts into performance mode.The key is to trust the taper, maintain consistency with reduced load, prioritise recovery, and avoid unnecessary changes.You don’t gain fitness in the final weeks, you allow it to show.Inigo Mujika & Sabino Padilla (2003) “Scientific bases for precompetition tapering strategies” Medicine & Science in Sports & Exercise Inigo Mujika (2010) “Intense training: the key to optimal performance before and during the taper” Scandinavian Journal of Medicine & Science in Sports Thomas D. Bosquet et al. (2007) “Effect of tapering on performance: a meta-analysis” Medicine & Science in Sports & Exercise → David C. Nieman (1998, 2000) Research on immune function and recovery Asker Jeukendrup Multiple publications on endurance performance Timothy Noakes (2012) “Lore of Running” American College of Sports Medicine (ACSM Guidelines)NSCA Essentials of Strength Training & Conditioning

HRV, or heart rate variability, is not a score that tells ultrarunners whether they are fit or unfit on a given day. It is a signal of how well the body is handling overall stress. That stress comes not only from training, but also from sleep, work, travel, fuelling, illness, and life outside running.The key idea in the episode is that HRV is most useful when viewed as a trend, not as a single daily number. One low reading does not mean much on its own, but a drop over several days, especially alongside tired legs, poor mood, or bad sleep, can be an early warning sign that recovery is slipping.The episode also explains that runners often misuse HRV by treating it like a green-or-red traffic light. Instead, HRV should be combined with how you feel, your sleep, resting heart rate, and how training is going. It can be especially useful for deciding whether it is the right day for a hard session or whether recovery should come first.The main takeaway is this: don’t chase a perfect HRV score, use HRV to understand whether your body is absorbing training or just accumulating stress.Key references:Buchheit, M. (2014). Monitoring training status with HR measures: do all roads lead to Rome? Frontiers in Physiology. Esco, M. R., Flatt, A. A., Nakamura, F. Y., et al. (2025). Monitoring Training Adaptation and Recovery Status in Athletic Populations Using Heart Rate Variability. Sports Medicine / PMC review. Düking, P., Zinner, C., Reed, J. L., et al. (2021). Monitoring and adapting endurance training on the basis of heart rate variability monitored by wearable technologies: A systematic review with meta-analysis. Journal of Science and Medicine in Sport. Manresa-Rocamora, A., Sarabia, J. M., Javaloyes, A., et al. (2021). Heart Rate Variability-Guided Training for Enhancing Cardiac-Vagal Modulation, Aerobic Fitness, and Endurance Performance: A Systematic Review with Meta-Analysis. International Journal of Environmental Research and Public Health. Schmitt, L., Regnard, J., Parmentier, A.-L., et al. (2015). Monitoring Fatigue Status with HRV Measures in Elite Athletes: An Avenue Beyond RMSSD? Frontiers in Physiology.Sammito, S., Böckelmann, I., et al. (2024). Update: factors influencing heart rate variability – a narrative review. Frontiers in Physiology. Herzig, D., Eser, P., Omlin, X., et al. (2018). The Association Between Endurance Training and Heart Rate Variability: The Confounding Role of Heart Rate. Frontiers in Physiology.

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.

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.

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 effortsCarb tank = smaller, faster energy, increasingly important as intensity risesIt then shows how this appears in training and racing:Easy long runs often feel manageableHarder sessions, climbs, and surges can quickly increase carb demand and lead to fatigue if under-fueledCommon 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 strategyPractical advice:Match fueling to the session goalPractice race fueling in trainingUse 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 takeawayPace 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.

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).

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

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.