How Much is Too Much? A Critical Look at “Physiology and Pathophysiology of Marathon Running” by Braschler et al. (2025) | Find Your Stride | Edinburgh Podiatrist

Marathon running has long held a reputation for being the ultimate test of human endurance. But what really happens to your body when you train for and complete 42.195 kilometres? The recently published narrative review by Braschler et al., “Physiology and Pathophysiology of Marathon Running” (2025), sets out to answer that question in exceptional depth. While the paper offers a thorough and ambitious look into the benefits and risks of marathon running, its practical value for runners focused on performance is somewhat mixed.

Have you ever wondered what really happens to your body when you train for and complete 42.195 kilometres?

The Good: A Comprehensive Tour of the Human Body Under Strain

Braschler et al. deserve credit for producing one of the most sweeping reviews of marathon physiology to date. The paper synthesises findings from over 300 studies and systematically addresses how marathon running affects nearly every organ system, from the cardiovascular and renal systems to immune and endocrine responses.

For athletes and coaches seeking a detailed breakdown of potential risks, such as acute kidney injury, cardiac biomarker spikes, or hormonal disruption the paper is a gold mine. It’s particularly illuminating in its discussion of:

• Cardiovascular adaptations: including reduced blood pressure, increased stroke volume, and long-term cardiac remodelling (the so-called “athlete’s heart”).

• Biomarker changes: covering elevations in troponin, cortisol, and interleukin-6, among others - most of which normalise within days post-race.

• Injury and immune risks: like gastrointestinal distress, musculoskeletal injury, or transient immunosuppression post-race.

From a health safety standpoint, the review reassures that marathon running is generally safe, provided athletes train properly and are medically screened.

The Bad: Where’s the Performance Lens?

For a blog focused on running performance, the major critique is the lack of actionable insights for optimising training, pacing, or race-day strategy. The review is rich in medical and biochemical detail, but less so in performance-enhancing takeaways. Topics like:

• Tapering strategies

• Pacing optimisation

• Training volume thresholds for adaptation vs. overtraining

are only briefly mentioned or omitted entirely. Given that performance and overtraining are intimately connected, this feels like a missed opportunity.

Additionally, while the authors cite data on cardiac fibrosis, atrial fibrillation, and post-race heart dysfunction in veteran runners, they don’t offer clear guidance on what thresholds (e.g., years of training, mileage, intensity) might elevate these risks. This could create unnecessary fear or confusion among experienced runners.

The Ugly: Science Overload Without Context

The paper presents a barrage of biomarkers, physiological parameters, and clinical studies - but with limited context for the non-specialist. For instance, marathon-induced elevations in cardiac troponins are described as “transient and usually harmless,” but there’s little help for runners trying to distinguish normal from dangerous symptoms. Similarly, the discussion on electrolyte imbalances or hormonal disruption lacks practical tips like hydration strategies or recovery protocols.

The narrative style also means the review lacks a strong organising framework or visual aids beyond tables, which makes digesting the data laborious.

Bottom Line: Valuable for Coaches and Medical Teams — Less so for Performance-Focused Runners

If you’re a coach, sports physician, or researcher looking to understand how marathon running affects the human body from head to toe, this review is a must-read. But if your goal is to run faster, smarter, or longer without injury, you’ll have to dig deep to extract performance-specific insights — or look elsewhere entirely.

What We’d Like to See Next:

• A practical companion guide focused on training thresholds, fueling, hydration, and recovery strategies.

• Longitudinal data tying biomarker changes to actual performance declines or injury over time.

• Insights tailored for different athlete types: recreational vs. elite, young vs. veteran, male vs. female.

Until then, keep running smart, and maybe get that heart check before your next PR attempt.

Find Your Stride!