In this article:
- Why socks matter in marathons
- Temperature regulation over 26.2 miles
- Blister prevention science
- Moisture management
- The Moggans approach
Why serious marathon runners are choosing Merino wool over synthetic socks
Marathon runners are a particular breed. Training plans are refined down to individual sessions, nutrition is rehearsed, shoes are rotated and retired with care. Yet one item is still often underestimated: the sock.
Over 26.2 miles, your feet will strike the ground tens of thousands of times. Each step generates heat, friction and moisture. Small discomforts that go unnoticed early on can become decisive in the final miles — blisters, overheating, dampness, and distraction arriving just when focus matters most.
For years, synthetic socks dominated marathon running. Lightweight, quick-drying and inexpensive, they were considered the default performance option. But among experienced marathoners — and increasingly among elite and ultra-distance runners — that assumption is being quietly challenged.
More and more are turning to Merino wool. Not out of nostalgia, but because the evidence increasingly supports it. For a comprehensive comparison of Merino vs synthetic performance across different conditions, see our Base Layer Guide: Merino vs Synthetic.
Why socks matter more in a marathon than any other race
A marathon is unlike any other running event. It is not simply about speed; it is about sustaining comfort and efficiency over several hours of continuous movement.
Feet heat up as blood flow increases. Sweat accumulates. Weather conditions change. Pace fluctuates. By mile twenty, swelling, fatigue and moisture combine to amplify every small irritation.
Socks sit at the critical interface between foot and shoe. They influence how heat is retained or released, how moisture is managed, and how much friction builds up with each stride. Over marathon distance, these factors matter as much as shoe choice.
Temperature regulation: adapting over 26.2 miles
The marathon problem
Most marathons begin cool and finish warm. Spring races in the UK are especially unpredictable — cold winds on the start line, rising temperatures by midday, rain at any stage.
Synthetic fibres are effective at transporting liquid sweat, but they do little to stabilise temperature. As conditions change, performance can fluctuate.
Why Merino behaves differently
Merino wool fibres are hygroscopic, meaning they absorb moisture vapour into the fibre structure while remaining dry to the touch. This process helps regulate temperature by buffering heat and moisture changes at the skin.
Industry research and textile studies show that this moisture buffering contributes to a more stable microclimate — particularly valuable during long-duration endurance exercise.
What this means on race day
A well-designed Merino sock can take you from a cold start through a warm finish without overheating or chilling. Instead of reacting to conditions, the fibre helps manage them for you.
Blister prevention: friction, heat and moisture
The common misconception
Blisters are often blamed on ill-fitting shoes or bad luck.
The reality
Blisters form when heat, moisture and friction combine over time. Remove or reduce one of these factors and the risk falls sharply.
The fibre effect
Smooth synthetic fibres can increase friction at the skin–sock interface once moisture builds up. Wool fibres, by contrast, have a naturally complex structure and flex under load, helping to moderate friction during repetitive movement.
Peer-reviewed sock fabric studies show that fibre type and fabric construction directly influence thermal comfort and moisture behaviour, both of which are closely linked to blister risk over long distances.
Over marathon distance
This matters most in the final third of the race, when feet are warm, swollen and fatigued. Reducing friction at that stage can preserve running form and prevent small problems becoming race-ending ones.
Moisture management: beyond simple "wicking"
Where synthetics fall short
Synthetic socks move sweat away from the skin, but often trap that moisture within the fabric. Late in a marathon, this can leave feet feeling damp and clammy.
How Merino manages moisture
Merino wool works differently. It:
- Absorbs moisture vapour into the fibre core
- Buffers moisture within the fibre structure
- Releases it gradually through evaporation
This reduces surface wetness and helps maintain a drier feel against the skin, even when overall sweat levels are high.
The runner's experience
Many marathon runners report that Merino socks feel drier deeper into long runs — not because they prevent sweating, but because they manage it more effectively.
Odour control: a secondary but meaningful benefit
Why odour matters
Odour is not just unpleasant; it signals bacterial growth, which thrives in warm, damp environments.
The Merino advantage
Merino wool is naturally odour resistant. Its fibre structure absorbs odour molecules rather than allowing them to build up on the surface. This is an inherent property of the fibre, not a chemical treatment that washes out.
Practical benefits
For marathon training blocks, this means socks can often be aired between sessions and re-worn without noticeable odour — extending lifespan and reducing washing.
Durability: thinking in miles, not washes
The assumption
Synthetic socks are often assumed to last longer.
What actually happens
Many synthetic running socks rely on elastane for stretch and compression. Over time, heat, friction and washing degrade these fibres, leading to loss of fit and support.
Merino wool fibres have natural crimp and elasticity. When engineered correctly, they maintain structure and recovery over hundreds of miles of training.
Cost per mile
A high-quality Merino sock may cost more initially, but across a full marathon training cycle it often proves the better investment.
Sustainability: performance with responsibility
Marathon runners think long-term — about training, health and resilience. Increasingly, they think the same way about impact.
Synthetic socks shed microplastics during washing and are derived from fossil fuels. Merino wool is renewable, biodegradable and naturally circular.
Choosing Merino does not mean compromising on performance. It enhances it — while reducing environmental cost.
The Moggans approach
At Moggans, Merino wool is not a marketing story. It is a material choice.
We use mulesing-free Merino wool, independently certified and tested, selected for durability, comfort and performance over distance. Our Ultralight Speed socks are designed specifically for running: secure fit, seamless construction, targeted cushioning and ventilation — nothing unnecessary, nothing accidental.
They are built to disappear on the run. Which, for a marathon sock, is the highest compliment.
The verdict: what the evidence shows
When you step back from brand claims and look instead at independent textile research, industry science and long-distance runner experience, a consistent picture emerges.
Merino wool offers clear advantages for marathon running where duration, moisture management and thermal stability matter most. Synthetic socks remain popular for their low weight and lower upfront cost, but they are less effective at managing changing conditions over several hours of continuous movement.
When durability, late-race comfort and environmental impact are considered together, Merino wool increasingly stands out as the more considered choice.
Not because it is fashionable — but because it performs.
Ready to make the switch?
The Moggans Ultralight Speed Ankle Socks are designed in Scotland and built for marathon training and race day. Made using mulesing-free Merino wool, they are tested over long training blocks and proven where it matters most — mile after mile.
For help choosing the right running socks for your training and race goals, check out our Running Sock Buying Guide: Road vs Trail vs Ultra.
Marathon Season 2026
Training for London, Edinburgh, Manchester, Brighton, Paris, Boston, New York or Frankfurt?
Start your training in the socks you intend to race in.
Frequently Asked Questions
Q: Are Merino socks better than synthetic for marathons?
A: Yes, Merino wool offers superior temperature regulation, moisture management, and blister prevention over marathon distance. The natural fibre properties help maintain comfort through changing conditions over several hours of running.
Q: How long do Merino marathon socks last?
A: High-quality Merino socks like Moggans Ultralight Speed maintain performance through 500+ miles of training when properly cared for. This is typically longer than synthetic socks, which often lose compression and fit after 200-300 miles.
Q: Can I wear Merino socks in warm weather marathons?
A: Yes, Merino naturally regulates temperature and works well in both cool and warm conditions. The fibres absorb moisture while remaining dry to the touch, helping prevent overheating even in spring and summer races.
Q: Do I need different socks for training vs race day?
A: No, you should train in the same socks you plan to race in. This allows you to test fit, comfort and blister prevention over long distances. We recommend buying 2-3 pairs to rotate through your training block.
Q: How do I care for Merino running socks?
A: Wash in cold water (30°C max) with Woolmark-approved detergent and air dry. Never tumble dry as heat damages Merino fibres. Proper care extends lifespan significantly. See our full care guide.
Sources & further reading
- The Woolmark Company — Merino wool performance, moisture management and odour resistance
- International Wool Textile Organisation (IWTO) — How wool excels at sports: the thermoregulation advantage
- Van Amber et al. — Thermal and moisture transfer properties of sock fabrics differing in fibre type, yarn and fabric structure (peer-reviewed textile research)
