Explorez tous les épisodes du podcast The Trail Running Briefing

Peak form is not simply about being as fit as possible. It is the point where high fitness meets low fatigue, allowing an athlete to fully express the adaptations built over weeks and months of training.

Hard training develops aerobic fitness, strength, durability, climbing and descending ability, but it also creates fatigue. This means runners can sometimes be getting fitter while temporarily feeling slower or heavier. Tapering works by reducing that fatigue while preserving the fitness already developed.

Research supports substantially reducing training volume before an important race while maintaining some intensity. The purpose is not to create new fitness at the last minute, but to reveal the fitness already there.

Peak form should also be viewed as a window rather than a permanent state. Fitness can be maintained for relatively long periods, but the ideal combination of fitness, freshness, race specificity and psychological readiness cannot be held indefinitely.

After an A-race, the goal should therefore not be to stay at your peak, but to repeat the cycle:

RECOVER → REBUILD → DEVELOP → TAPER → PEAK AGAIN.

The key message of the episode is simple:

Training builds the fitness. Tapering reveals it.

1. Wang, Z., Wang, Y., Gao, W., & Zhong, Y. (2023).Effects of tapering on performance in endurance athletes: A systematic review and meta-analysis. PLOS ONE, 18(5), e0282838.DOI: 10.1371/journal.pone.0282838

2. Bosquet, L., Montpetit, J., Arvisais, D., & Mujika, I. (2007).Effects of tapering on performance: A meta-analysis. Medicine & Science in Sports & Exercise, 39(8), 1358–1365.

3. Mujika, I., & Padilla, S. (2003).Scientific bases for precompetition tapering strategies. Medicine & Science in Sports & Exercise, 35(7), 1182–1187.DOI: 10.1249/01.MSS.0000074448.73931.11

4. Calvert, T. W., Banister, E. W., Savage, M. V., & Bach, T. (1976).A systems model of the effects of training on physical performance. IEEE Transactions on Systems, Man, and Cybernetics, 6(2), 94–102.DOI: 10.1109/TSMC.1976.5409179

5. Spiering, B. A., Mujika, I., Sharp, M. A., & Foulis, S. A. (2021).Maintaining Physical Performance: The Minimal Dose of Exercise Needed to Preserve Endurance and Strength Over Time. Journal of Strength and Conditioning Research, 35(5), 1449–1458.DOI: 10.1519/JSC.0000000000003964

6. Millet, G. Y., Tomazin, K., Verges, S., Vincent, C., Bonnefoy, R., Boisson, R. C., et al. (2011).Neuromuscular Consequences of an Extreme Mountain Ultra-Marathon. PLOS ONE, 6(2), e17059.DOI: 10.1371/journal.pone.0017059

In Episode 30 of The Trail Running Briefing, we explore why ultrarunners sometimes stop improving even when they are training consistently and working harder.

A plateau doesn’t always mean you need more mileage or more intensity. It can mean your body has adapted to the same training stimulus, accumulated fatigue is hiding your fitness, recovery or fuelling is insufficient, or your training is no longer targeting the qualities that actually limit your performance.

We look at the importance of purposeful progression, keeping easy runs genuinely easy, strength training, durability, recovery weeks, adequate fuelling and race-specific preparation.

The key message is simple: training is not about collecting more kilometres, it is about creating adaptation. Before doing more, understand what needs to change.

Key References:

1. Zanini, M., Folland, J. P., & Blagrove, R. C. (2026).Regular Long Runs and Higher Training Volumes Are Associated with Better Running Economy Durability in Performance-Matched Well-Trained Male Runners.Medicine & Science in Sports & Exercise, 58(1), 162–173.

2. Zanini, M., Folland, J. P., Wu, H., & Blagrove, R. C. (2025).Strength Training Improves Running Economy Durability and Fatigued High-Intensity Performance in Well-Trained Male Runners: A Randomized Controlled Trial.Medicine & Science in Sports & Exercise, 57(7), 1546–1558.

3. Tiller, N. B., & Millet, G. Y. (2025).Decoding Ultramarathon: Muscle Damage as the Main Impediment to Performance.Sports Medicine, 55(3), 535–543.

4. Llanos-Lagos, C., Ramirez-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(4), 895–932.

5. Sperlich, B. et al. (2023).The Proportional Distribution of Training by Elite Endurance Athletes at Different Intensities During Different Phases of the Season.Frontiers in Sports and Active Living, 5, 1258585.

6. Oliveira, P. S. et al. (2024).Comparison of Polarized Versus Other Types of Endurance Training Intensity Distribution on Athletes' Endurance Performance: A Systematic Review and Meta-analysis.

7. Mountjoy, M. et al. (2023).2023 International Olympic Committee's (IOC) Consensus Statement on Relative Energy Deficiency in Sport (REDs).British Journal of Sports Medicine, 57, 1073–1097.

8. Meeusen, R., Duclos, M., Foster, C., Fry, A., Gleeson, M., Nieman, D., Raglin, J., Rietjens, G., Steinacker, J., & Urhausen, A. (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.Medicine & Science in Sports & Exercise, 45(1), 186–205.

Ultra running demands far more than just mileage. Long runs, back-to-backs, strength work, fuelling, recovery, work, family and everyday stress all contribute to the total load an athlete carries.

In this episode, I explore burnout in ultrarunning, how it differs from normal fatigue or overtraining, and why it can gradually turn something we love into something that feels like an obligation.

We look at the key warning signs, physical and emotional exhaustion, declining motivation, reduced sense of achievement and losing enjoyment in the sport, and most importantly, what runners can do to reduce the risk.

The central message is simple: your real training load is training plus everything else happening in your life.

Sustainable ultra running isn’t about doing the maximum training you can survive. It’s about training at a level you can repeatedly absorb while protecting your motivation, health and love for running.

Key references:

1. Raedeke, T. D., & Smith, A. L. (2001). Development and preliminary validation of an Athlete Burnout Measure. Journal of Sport & Exercise Psychology, 23(4), 281–306.

2. Gustafsson, H., DeFreese, J. D., & Madigan, D. J. (2017). Athlete burnout: Review and recommendations. Current Opinion in Psychology, 16, 109–113.

3. Lonsdale, C., Hodge, K., & Rose, E. A. (2009). Athlete burnout in elite sport: A self-determination perspective. Journal of Sports Sciences, 27(8), 785–795.

4. Kellmann, M., Bertollo, M., Bosquet, L., et al. (2018). Recovery and Performance in Sport: Consensus Statement. International Journal of Sports Physiology and Performance, 13(2), 240–245.

5. Cresswell, S. L., & Eklund, R. C. (2005). Changes in athlete burnout and motivation over a 12-week league tournament. Medicine & Science in Sports & Exercise.

Episode 28 explores how ultra training should evolve with age without lowering ambition. The central idea is the recovery budget: every long run, hard session, strength workout and race creates stress, while sleep, work, nutrition and life commitments affect how quickly that budget is restored.

As runners get older, training does not necessarily need to become easier, but it should become less crowded and more purposeful. This means allowing more recovery between demanding sessions, maintaining strength training, using intensity selectively and treating races as major training loads rather than casual additions to the calendar.

The episode also stresses that sustainable training matters at every age. Younger runners may tolerate poor decisions for longer, but repeated overload can still lead to injury, fatigue and burnout. The key message is:

Do not ask how much training you can survive. Ask how much training you can absorb and repeat for years.

Key references:

1. Tanaka H, Seals DR. Endurance exercise performance in Masters athletes: age-associated changes and underlying physiological mechanisms. The Journal of Physiology. 2008;586(1):55–63. doi: 10.1113/jphysiol.2007.141879

2. Borges N, Reaburn P, Driller M, Argus C. Age-related changes in performance and recovery kinetics in Masters athletes: a narrative review. Journal of Aging and Physical Activity. 2016;24(1):149–157. doi: 10.1123/japa.2015-0021

3. Valenzuela PL, Maffiuletti NA, Joyner MJ, Lucia A, Lepers R. Lifelong endurance exercise as a countermeasure against age-related VO₂max decline: physiological overview and insights from Masters athletes. Sports Medicine. 2020;50(4):703–716. doi: 10.1007/s40279-019-01252-0

4. Fragala MS, Cadore EL, Dorgo S, et al. Resistance training for older adults: position statement from the National Strength and Conditioning Association. Journal of Strength and Conditioning Research. 2019;33(8):2019–2052. doi: 10.1519/JSC.0000000000003230

5. Llanos-Lagos C, Ramirez-Campillo R, Moran J, Sáez de Villarreal E. Effect of strength-training programs on middle- and long-distance runners’ economy at different running speeds: a systematic review with meta-analysis. Sports Medicine. 2024;54(4):895–932. doi: 10.1007/s40279-023-01978-y

6. Herbert P, Hayes LD, Sculthorpe NF, Grace FM. HIIT produces increases in muscle power and free testosterone in male Masters athletes. Endocrine Connections. 2017;6(7):430–436. doi: 10.1530/EC-17-0159

7. Soligard T, Schwellnus M, Alonso JM, et al. How much is too much? Part 1: International Olympic Committee consensus statement on load in sport and risk of injury. British Journal of Sports Medicine. 2016;50(17):1030–1041. doi: 10.1136/bjsports-2016-096581

8. Doering TM, Reaburn PR, Phillips SM, Jenkins DG. Postexercise dietary protein strategies to maximize skeletal-muscle repair and remodeling in Masters endurance athletes: a review. International Journal of Sport Nutrition and Exercise Metabolism. 2016;26(2):168–178. doi: 10.1123/ijsnem.2015-0102

9. Tiller NB, Millet GY. Decoding ultramarathon: muscle damage as the main impediment to performance. Sports Medicine. 2025;55(3):535–543. doi: 10.1007/s40279-024-02127-9

After a DNF, remember this sequence:

Feel it. Separate it. Learn from it. Then move forward.

Feel the disappointment without shame. Separate the facts from the story you are telling about yourself. Extract a small number of useful lessons. Then rebuild through ordinary, consistent action.

A DNF is painful because the goal mattered. But it is a result, not an identity. It records where one race ended; it does not decide where your running ends.

So keep this sentence for the difficult days after an unfinished race:

“I did not finish this race—but this race has not finished me.”

Key references:

1. Mosewich, A. D., Crocker, P. R. E., Kowalski, K. C., & DeLongis, A. (2013). Applying self-compassion in sport: An intervention with women athletes. Journal of Sport & Exercise Psychology, 35(5), 514–524. DOI: 10.1123/jsep.35.5.514
2. Ceccarelli, L. A., Giuliano, R. J., Glazebrook, C. M., & Strachan, S. M. (2019). Self-compassion and psycho-physiological recovery from recalled sport failure. Frontiers in Psychology, 10, 1564. DOI: 10.3389/fpsyg.2019.01564
3. Zhang, N., Huang, J., & Yao, J. (2023). Athletes’ self-compassion and emotional resilience to failure: The mediating role of vagal reactivity. Frontiers in Psychology, 14, 1192265. DOI: 10.3389/fpsyg.2023.1192265
4. Kuchar, A. L., Neff, K. D., & Mosewich, A. D. (2023). Resilience and Enhancement in Sport, Exercise, & Training—RESET: A brief self-compassion intervention with NCAA student-athletes. Psychology of Sport and Exercise, 67, 102426. DOI: 10.1016/j.psychsport.2023.102426
5. Neumann, D. L., & McInnes, M. (2025). A brief writing intervention assists athletes to cope with performance failures. PsyCh Journal, 14(5), 787–798. DOI: 10.1002/pchj.70026
6. Alipour Ataabadi, Y., Cormier, D. L., Kowalski, K. C., Oates, A. R., Ferguson, L. J., & Lanovaz, J. L. (2022). The associations among self-compassion, self-esteem, self-criticism, and concern over mistakes in response to biomechanical feedback in athletes. Frontiers in Sports and Active Living, 4, 868576. DOI: 10.3389/fspor.2022.868576

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:

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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.

8. Knechtle, B., & Nikolaidis, P. T. (2018). Physiology and Pathophysiology in Ultra-Marathon Running. Frontiers in Physiology, 9, 634. DOI: 10.3389/fphys.2018.00634.

9. 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.

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:

1. Thomas, D. T., Erdman, K. A., & Burke, L. M. — “Nutrition and Athletic Performance.”

2. Burke, L. M., Hawley, J. A., Wong, S. H. S., & Jeukendrup, A. E. — “Carbohydrates for training and competition.”

3. Wallis, G. A. — “Dietary Carbohydrate and the Endurance Athlete: Contemporary Perspectives.”

4. Vitale, K., & Getzin, A. — “Nutrition and Supplement Update for the Endurance Athlete.”

5. Kerksick, C. M. et al. — “International Society of Sports Nutrition Position Stand: Nutrient Timing.”

6. Mata, F. et al. — “Carbohydrate Availability and Physical Performance.”

7. Naderi, A. et al. — “Carbohydrates and Endurance Exercise: A Narrative Review.”

8. Thomas / ACSM position statement — race-day fuelling section

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:

1. Pageaux, B. - “The psychobiological model of endurance performance”

2. Marcora et al. - “Mental fatigue impairs physical performance in humans”

3. Blanchfield et al. - “Talking yourself out of exhaustion: the effects of self-talk on endurance performance”

4. Burgum et al. - “Reduced mood variability is associated with enhanced performance in ultramarathon running”

5. Bieleke et al. - “If-then planning”

6. Tiller et al. - “International Society of Sports Nutrition Position Stand: Nutritional considerations for single-stage ultra-marathon training and racing”

7. Hew-Butler et al. - “Exercise-Associated Hyponatremia: 2017 Update”

8. Cao et al. - “Head, face and neck cooling as per-cooling during exercise in the heat”

9. Bongers et al. - “Cooling interventions for athletes”

10. Costa et al. - “Nutrition for Ultramarathon Running: Trail, Track, and Road”

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:

1. Racinais et al. 2015 — Consensus Recommendations on Training and Competing in the Heat

2. Racinais et al. 2023 — IOC Consensus Statement on Recommendations and Regulations for Sport Events in the Heat

3. Zurawlew et al. 2018 — Post-exercise Hot Water Immersion as a Practical Heat Acclimation Strategy

4. Zurawlew et al. 2019 — Hot Water Immersion, Retention of Heat Adaptations

5. Scoon et al. 2007 — Post-exercise Sauna Bathing and Endurance Performance in Competitive Runners

6. Casa et al. 2015 — National Athletic Trainers’ Association Position Statement: Exertional Heat Illnesses

7. Roberts et al. 2021/2023 — ACSM Expert Consensus Statement on Exertional Heat Illness

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:

1. Androulakis-Korakakis et al. — The Minimum Effective Training Dose Required to Increase 1RM Strength in Resistance-Trained Men

2. Schoenfeld et al. — Resistance Training Volume Enhances Muscle Hypertrophy but Not Strength in Trained Men

3. Hughes et al. — Adaptations to Endurance and Strength Training

4. Spiering et al. — Maintaining Physical Performance: The Minimal Dose of Exercise Needed to Preserve Endurance and Strength Over Time

5. Rosenblat et al. — Polarized vs Threshold Training: Systematic Review and Meta-analysis

6. Muñoz et al. — Does Polarized Training Improve Performance in Recreational Runners?

7. Oliveira et al. — Comparison of Polarized Versus Other Types of Endurance Training Intensity Distribution

8. Tallis et al. — Repeated Bout Effect of Downhill Running on Physiological Markers and Muscle Soreness

9. Assumpção et al. — A Single Bout of Downhill Running Attenuates Subsequent Exercise-Induced Muscle Damage

10. Martinez-Navarro et al. — Downhill Running-Induced Muscle Damage in Trail Runners

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:

1. Bontemps, B. et al. (2020). Downhill Running: What Are The Effects and How Can We Adapt? A Narrative Review. Sports Medicine.

2. Bontemps, B. et al. (2020). Full-text review via PMC.

3. 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.

4. Coratella, G. et al. (2024). Downhill running increases markers of muscle damage and alters jump performance.

5. Martínez-Navarro, I. et al. (2026). Downhill Running-Induced Muscle Damage in Trail Runners: An Exploratory Study Regarding Training Background and Running Gait. Sports.

6. Genitrini, M. et al. (2022). Downhill Sections Are Crucial for Performance in Trail Running.

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.

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.

This episode explains why running performance drops in hot conditions and why it is not simply a loss of fitness or lack of toughness. In the heat, the body has two jobs: keep running and protect itself from overheating. More blood is directed towards the skin for cooling, sweat rate increases, heart rate rises, and the same pace costs more energy.

The key message is that on hot days, effort matters more than pace. A pace that feels easy in cool weather may become moderate or hard in the heat. Trying to force normal pace often leads to overheating, dehydration, gut problems, and a major slowdown later.

If a hot race is expected, heat acclimation over 10–14 days can improve tolerance. But when a heatwave arrives suddenly, the goal is damage control: slow down early, reduce intensity, walk climbs sooner, use shade, cool aggressively, hydrate sensibly, and protect the gut.

Main takeaway: In the heat, do not fight for your normal pace. Manage your effort, stay cool, and slow down before your body forces you to slow down.

Key references:

• González-Alonso, J. 2007. The cardiovascular challenge of exercising in the heat. Journal of Physiology.
• Wingo, J. E., Ganio, M. S., & Cureton, K. J. 2012. Cardiovascular drift during heat stress: implications for exercise prescription. Exercise and Sport Sciences Reviews.
• Périard, J. D., Eijsvogels, T. M. H., & Daanen, H. A. M. 2021. Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies. Physiological Reviews.
• Racinais, S. et al. 2015. Consensus recommendations on training and competing in the heat. Scandinavian Journal of Medicine & Science in Sports.
• Racinais, S. et al. 2023. IOC consensus statement on recommendations and regulations for sport events in the heat. British Journal of Sports Medicine.
• Heathcote, S. L. et al. 2018. Reviewing practical heat acclimation strategies for endurance athletes. Frontiers in Physiology.
• Zurawlew, M. J. et al. 2018. Post-exercise hot water immersion elicits heat acclimation adaptations in endurance trained and recreationally active individuals. Frontiers in Physiology.
• Wierick, S. C. et al. 2025. Hydration Strategies in Ultra-Endurance Running. Sports Medicine - Open / PMC.
• Knechtle, B. et al. 2019. Exercise-associated hyponatremia in endurance and ultra-endurance performance. Medicina.
• Hoffman, M. D. et al. 2015. Sodium Intake During an Ultramarathon Does Not Prevent Muscle Cramping, Dehydration, Hyponatremia, or Nausea. Sports Medicine - Open.

In this episode of The Trail Running Briefing, we explore why choosing a race with purpose can be a powerful part of ultra-distance performance.

Training, pacing, fuelling, strength, and recovery all matter, but when a race becomes difficult, runners also need a strong reason to keep moving. Purpose gives suffering direction. It helps runners stay patient, calm, and committed when fatigue, bad weather, stomach issues, or doubt begin to take over.

The episode explains that purpose is not just emotion or motivation. It becomes useful when it shapes real behaviour: choosing the right race, training consistently, practising specific skills, respecting the demands of the course, and creating process goals that support the bigger reason.

The key message is simple:

Do not just choose the race. Choose the reason.

Because when the easy motivation disappears, purpose may be what helps you find one more step.

Key references:

• Teixeira, P. J. et al. (2012). Exercise, physical activity, and self-determination theory: A systematic review. International Journal of Behavioral Nutrition and Physical Activity.

• Williamson, O. et al. (2024). The performance and psychological effects of goal setting in sport: A systematic review and meta-analysis. International Review of Sport and Exercise Psychology.

• Healy, L., Tincknell-Smith, A., & Ntoumanis, N. (2018). Goal Setting in Sport and Performance. Oxford Research Encyclopedia of Psychology.

• Schiphof-Godart, L., Roelands, B., & Hettinga, F. J. (2018). Drive in Sports: How Mental Fatigue Affects Endurance Performance. Frontiers in Psychology.

• Méndez-Alonso, D. et al. (2021). Influence of Psychological Factors on the Success of the Ultra-Trail Runner. International Journal of Environmental Research and Public Health.

• Taylor, I. (2018). The Five Self-Determination Mini-Theories Applied to Sport. Loughborough University / Routledge chapter.

• Jeong, Y. H. et al. (2023). The application of Goal Setting Theory to goal setting interventions in sport: A systematic review. International Review of Sport and Exercise Psychology.

This episode explains why recovery is one of the biggest limiting factors in ultrarunning performance. The key idea is that training does not create fitness by itself, training creates stress, and recovery allows the body to adapt.

The episode challenges the common mistake of treating recovery as something you can buy or add at the end, such as massage, compression boots, red light therapy, or other gadgets. These tools may help some runners feel better, but they are secondary. They cannot compensate for poor training structure, under-fuelling, lack of sleep, or high life stress.

The four fundamental recovery pillars are:

Sensible training: protecting easy runs, using de-load weeks, and respecting race recovery.

Food: eating enough protein, carbohydrates, fats, and fuelling key sessions properly.

Sleep: the most powerful recovery tool, supporting repair, immune function, mood, and performance.

Stress management: recognising that work, family, emotional pressure, and life load all affect the same recovery system.

The practical message is that ultrarunners should stop asking, “How much training can I survive?” and start asking, “How much training can I absorb?”

Fitness is not built by the training you complete. It is built by the training you recover from.

Key references:

• Kellmann, M. et al. (2018). Recovery and Performance in Sport: Consensus Statement. International Journal of Sports Physiology and Performance.
• Thomas, D. T., Erdman, K. A., & Burke, L. M. (2016). Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance.
• Kerksick, C. M. et al. (2017). International Society of Sports Nutrition Position Stand: Nutrient Timing. Journal of the International Society of Sports Nutrition.
• Jäger, R. et al. (2017). International Society of Sports Nutrition Position Stand: Protein and Exercise. Journal of the International Society of Sports Nutrition.
• Walsh, N. P. et al. (2021). Sleep and the Athlete: Narrative Review and 2021 Expert Consensus Recommendations. British Journal of Sports Medicine.
• Dupuy, O. et al. (2018). An Evidence-Based Approach for Choosing Post-exercise Recovery Techniques to Reduce Markers of Muscle Damage, Soreness, Fatigue, and Inflammation: A Systematic Review With Meta-analysis. Frontiers in Physiology.
• Mountjoy, M. et al. (2023). 2023 International Olympic Committee’s Consensus Statement on Relative Energy Deficiency in Sport. British Journal of Sports Medicine.
• Charest, J. & Grandner, M. A. (2020). Sleep and Athletic Performance: Impacts on Physical Performance, Mental Performance, Injury Risk and Recovery. Sleep Medicine Clinics / PMC.

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

Hydration in long trail running is not just about drinking water. It is about replacing enough fluid and sodium to stay functional as conditions, duration, and sweat losses increase. This episode explains why runners can drink plenty and still feel flat, thirsty, heavy, or cramp-prone when sodium intake does not match the demands of the session. It also unpacks the simple idea that water replaces volume, but sodium helps you retain and use that fluid effectively.

The episode then shows how this appears in real training, why many runners get it wrong by using the same plan in every condition or by drinking too much plain water, and how to build a more practical strategy based on weather, duration, and individual sweat loss.

Main takeaway: Hydration is not just water. On long runs, replace what you sweat, not just what you drink.

Key references:

1. American College of Sports Medicine. Exercise and Fluid Replacement.

2. World Athletics. Fluid Needs for Training, Competition, and Recovery in Athletes.

3. Gatorade Sports Science Institute. Hydration and Nutrition Considerations for Endurance Exercise in the Heat.

4. Gatorade Sports Science Institute. Sodium Ingestion, Thirst, and Drinking During Endurance Exercise.

5. Gatorade Sports Science Institute. Sweating Rate and Sweat Sodium Concentrations in Athletes: A Review of Methodology and Intra-/Interindividual Variability.

6. ACSM. 9 Facts About Hydration & Electrolytes.

7. Gatorade Sports Science Institute. Normative Data for Sweating Rate, Sweat Sodium Concentration, and Sweat Sodium Loss in Athletes.

8. Gatorade Sports Science Institute. Sodium-Free Fluid Ingestion Decreases Plasma Sodium During Exercise in the Heat.
   

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 fatigue is normal. Overtraining is not. And very often, what runners call “overtraining” is actually a mix of excessive load, poor recovery, and under-fuelling.

This episode explains the difference between normal fatigue, non-functional overreaching, true overtraining syndrome, and Relative Energy Deficiency in Sport, or RED-S. The key message is that not all fatigue is the same, and the solution depends on the cause.

For ultrarunners, the biggest risks often come from stacking hard training, life stress, poor sleep, and low energy availability for too long. Warning signs include persistent tiredness, loss of performance, poor recovery, low mood, repeated illness, hormonal disruption, and recurring injuries.

The practical takeaway is simple: monitor warning signs early, fuel properly for the work you are doing, and make recovery as deliberate as training. The goal is not to avoid fatigue, but to make sure it is recoverable.

Main takeaway: Your body does not adapt to training you survive. It adapts to training you can recover from.

Key references

• Meeusen et al. ECSS-ACSM consensus on overtraining syndrome.
• Mountjoy et al. 2023 IOC consensus statement on RED-S.
• Stellingwerff et al. Overtraining Syndrome and RED-S: shared pathways, symptoms and complexities.
• Saw et al. Subjective self-reported measures for monitoring athlete fatigue.
• IOC consensus on load in sport and risk of injury.

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.

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.

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.

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.

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.

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 Hutchinson
• Science of Ultra – multiple episodes on durability, fueling, and pacing.

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).

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.

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 Magness
• Fitness–Fatigue Model — Eric W. Banister
• What 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 Jornet
• Special Block Training: A Modern Approach to Endurance Training — Renato Canova

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 Sciences
• Chen, 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 Physiology
• Giandolini, M., et al. (2016)
  Impact of downhill running on neuromuscular fatigue and running economy in trail runners.
  Journal of Applied Physiology
• Vernillo, 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 Medicine
• Millet, G. Y., & Lepers, R. (2004)
  Alterations of neuromuscular function after prolonged running, cycling and skiing exercises.
  Sports Medicine
• Nicol, C., Komi, P. V., & Marconnet, P. (1991)
  Fatigue effects of marathon running on neuromuscular performance.
  Scandinavian Journal of Medicine & Science in Sports
• Saunders, P. U., Pyne, D. B., Telford, R. D., & Hawley, J. A. (2004)
  Factors affecting running economy in trained distance runners.
  Sports Medicine

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.