Unlocking Optimal Marathon Performance – Training Intensity Distribution | Find Your Stride | Edinburgh Podiatrist

In the pursuit of optimal performance, few topics stir as much debate among endurance athletes and coaches as training intensity distribution (TID). A recent large-scale study, “The Training Intensity Distribution of Marathon Runners Across Performance Levels” (Muniz-Pumares et al., 2024), analysed the training data of over 119,000 recreational marathon runners. While its scope is impressive, does its message hold up when we look through the lens of performance optimisation? Let’s take a critical look.

On the surface, the conclusion is simple: train more, mostly slow, and you’ll run faster.

The Study in a Nutshell

The authors analysed 16 weeks of training data from runners using Strava®, comparing TID - how training time is divided between low (Z1), moderate (Z2), and high (Z3) intensities against marathon finish times. The author's found:

• Faster runners train more: Up to 3× more weekly distance than slower runners.

• High performers rely heavily on Zone 1 (Z1) running.

• Pyramidal TID (Z1 > Z2 > Z3) is the most common and dominant strategy among the fastest athletes.

• Surprisingly, polarised TID (Z1 + Z3 emphasis, avoiding Z2) was uncommon.

On the surface, the conclusion is simple: train more, mostly slow, and you’ll run faster.

Strengths of the Study

This study breaks ground in several ways:

1. Massive dataset – Unlike most endurance training studies that rely on elite athletes or small cohorts, this study evaluates over 151,000 marathon performances. It’s a treasure trove of real-world training behaviour.

2. Democratised insights – By focusing on recreational runners, the paper offers practical insights for the average athlete, not just Olympians.

3. Clear association between volume and performance – The correlation between higher training volume (especially in Z1) and better marathon times is strong and statistically robust.

For those focused on optimising marathon performance, one lesson is hard to ignore: Volume matters. And the best way to accumulate it without burnout is in Z1.

But… Is Pyramidal Really Optimal?

The authors frame pyramidal TID as the de facto choice for high-performing runners, but this doesn’t mean it’s optimal. In fact, the study is descriptive, not prescriptive. It tells us what runners did, not what they should do. There’s a risk in interpreting correlation as causation. Did runners perform better because they used a pyramidal TID, or did their higher overall training volumes simply necessitate more Z1 work, which incidentally results in a pyramidal profile?

Worse still, the study acknowledges that true polarised training; a widely studied approach shown to improve performance in controlled trials was rare among these runners. Does this mean it’s ineffective, or just underutilised? The accuracy of training intensity distribution (TID) classification should also be considered. How many of these recreational athletes conducted a fitness test to determine their heart rate zones before/during their marathon training?

Missing the Mark on High-Intensity Work?

Another eyebrow-raiser: the strong positive correlation between Z3 training and slower marathon times. At first glance, this suggests that high-intensity work is counterproductive. But here’s the catch: recreational runners often misuse high-intensity training, doing too much, too often, or without sufficient base conditioning. This study doesn’t differentiate how Z3 was implemented. Was it structured interval training? Was it a weekly tempo run? Or just overzealous pacing? By lumping all Z3 work together, the study risks misrepresenting the value of well-executed high-intensity sessions, especially when done in moderation and strategically placed.

Durability: The Elephant in the Room

A key variable missing from the performance equation is durability, or the ability to maintain physiological performance under prolonged stress. As previous research (and even the authors themselves) have pointed out, lower-performing runners may have poorer durability, requiring them to run at lower relative intensities.

This complicates the interpretation of TID. Perhaps slower runners weren’t “choosing” to train more in Z2 and Z3. Instead, their Z1 pace may be so slow it borders on walking, skewing their TID profile upward in intensity by default.

Optimising performance isn’t just about accumulating volume, it’s about how much effective work you can tolerate and recover from. Durability metrics would have added essential context here.

What This Means for You

If you’re chasing a marathon PR, here’s what this study does (and doesn’t) say about optimising your training:

✅ Do build volume gradually, emphasising Z1 to support frequency and reduce injury risk.

✅ Do aim for a pyramidal distribution but don’t mistake it as gospel. It’s a natural outcome of higher volume.

❌ Don’t abandon high-intensity training entirely. Used strategically, Z3 efforts build speed, VO2max, and mental resilience.

❌ Don’t assume what’s common is what’s best. Pyramidal training is popular. That’s not the same as optimal.

Final Thoughts: Correlation Isn’t Optimisation

This study gives us an unprecedented snapshot of how recreational marathoners train. It’s useful. It’s insightful. But it’s not the final word on optimal performance.

True optimisation requires going beyond observation, into experimental design, controlled interventions, and individualised programming. The data tells us what is. The coach and athlete must determine what should be. If you’re serious about performance, don’t just copy the masses. Learn from them, then refine your training with purpose.

Find Your Stride!