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.

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.

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.

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.

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.

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.

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.

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.