Natural Fibers and Athletic Performance: Why Merino Wool Outperforms Synthetic Activewear
Nature solved the problem of performance long before it became an industry. The fibres that keep a living thing comfortable through heat, cold, and hard exertion evolved over millions of years, with an economy no laboratory has matched.
Modern performance apparel set that inheritance aside. It is built almost entirely from plastic. Polyester, nylon, and elastane became the standard for a simple reason: they were inexpensive, abundant, and easy to manufacture at scale. Performance against the body came second. An entire category then learned to engineer around the limits of synthetic fibres, layering on coatings, treatments, and finishes to approximate what a natural fibre does on its own.
Merino wool is the older and better answer. Bred over millennia to keep an animal alive across brutal temperature swings, it remains the most sophisticated performance material available. What follows is an examination of why, at the level of the fibre itself, natural materials govern athletic performance more completely than the synthetics that displaced them.
The Synthetic Default in Performance Apparel
The dominance of synthetic fibres in activewear was driven by cost. Petroleum-derived materials arrived mid-century as a cheap, durable, mass-producible alternative to natural fibres, and the apparel industry adopted them at scale long before anyone seriously asked how they performed against the body.
A synthetic fibre is fundamentally inert. It cannot absorb moisture into its structure, respond to changes in body temperature, or neutralise odour through its own composition. Each of these functions has to be simulated through a chemical finish, a mechanical weave, or an applied treatment, and every simulation fades with washing and time. A garment that impresses in the store often disappoints by its second year.
There is also a cost that never appears on the label. Synthetic textiles shed microscopic plastic fibres throughout their life, in wear and in every wash, and they persist in the environment for generations once discarded. The performance fades within seasons. The waste remains for lifetimes.
How Merino Wool Performs at the Fibre Level
Merino wool performs through its own composition. The advantage begins with structure. Each fibre carries a natural crimp, a fine spring-like waviness, that traps thousands of tiny pockets of still air along its length. Those air pockets are the engine of nearly everything merino does well. They insulate, they breathe, and they let the fibre manage heat and moisture dynamically as conditions change.
Synthetic materials depend on coatings or treatments to mimic these properties, while merino carries them in its structure. The performance does not wash out, wear off, or require renewal. It is built into the fibre.
Thermoregulation
Merino is an active fibre. It reacts to changes in body temperature, holding warmth when conditions are cold and releasing heat when they turn hot. In climate-controlled human trials, 100% merino base layers outperformed synthetics, cotton, and viscose during stop-go activity, holding the microclimate between fabric and skin steadier so the body works less to stay comfortable. The practical effect is one any athlete recognises: merino manages heat while you work, then preserves warmth the moment you stop, eliminating the clammy after-chill synthetics are known for.
Moisture Management
Merino’s fibre is hydrophobic on its outer surface and hydrophilic at its core. That dual structure lets it absorb up to a third of its own weight in moisture without feeling wet. Sweat is drawn off the skin, carried through the fabric, and released into the air as vapour, keeping the surface against the skin stable and dry under sustained effort.
The same structure is why merino resists odour. The fibre absorbs sweat and locks the molecules away inside itself until the garment is washed, denying odour-causing bacteria the surface moisture they need to multiply. The result is a garment that stays fresh through repeated wear and asks for fewer washes, which extends its life and lowers its footprint at the same time.
Durability
At a microscopic level, each merino fibre behaves like a coiled spring. It bends tens of thousands of times without breaking and returns to its original shape after stretching. That structural elasticity gives a merino garment its shape retention, its resistance to wrinkling, and its resilience under repeated wear. A garment built from it earns back its cost-per-wear over years of use.
What This Means for Training
A fibre that regulates temperature, manages moisture, and recovers its shape serves across many disciplines at once. The same garment moves with you from a cold morning run to a heated gym floor, from the stop-start rhythm of intervals to the long, steady output of distance, adjusting as conditions and effort change. One garment does the work that a wardrobe of single-purpose synthetics usually requires.
This is what School of Athens designs for: the roughest and finest conditions, the streets of New York City and the mountains of Italy. The ancients understood training as a discipline of body and mind together, a daily practice undertaken for its own sake, and the garment is built for that kind of sustained effort. A material this capable can be worn harder, washed less, and kept longer, which is the older meaning of performance, the kind measured across years of use.
Performance Without Environmental Cost
Performance apparel has long carried a hidden environmental cost. Synthetic garments are derived from fossil fuels, shed microplastics across their lifetime, and persist in landfill for generations after they are discarded. A material’s impact continues long after it leaves the body.
Merino offers a different arrangement. It is 100% natural and 100% renewable, since sheep grow a new fleece each year on water, air, sunshine, and grass. At the end of a garment’s life, 100% merino fabric returns to the earth. Buried in soil, it biodegrades by roughly 95% within fifteen weeks, releasing its nutrients back into the ground. The same fibre that performs against the body completes a genuine cycle once its use is over.
School of Athens builds on that foundation. Through a partnership with SeaTrees, we are a certified Ocean+Positive brand, sequestering more carbon than we emit through the restoration of kelp forests, coral reefs, and mangrove ecosystems. Every garment is designed, cut, sewn, and printed in New York City, alongside the craftsmen who share this city with us.
We do not claim perfection. We commit to measurable, ongoing regenerative impact, and to the principle that a garment should live in harmony with the natural world.
A Closing on Material as Philosophy
At the centre of School of Athens is a simple conviction: a garment should work with the body, not against it, and a business should live in harmony with the natural world. Choosing a natural fibre is a statement about the future as much as a respect for the past. The most advanced performance material was refined by the world itself over millennia, and the future of performance apparel lies in mastering what is already extraordinary.
The garden of the world has no limits except in your mind. — Rumi
Frequently Asked Questions
Is merino wool good for working out?
Yes. Merino regulates temperature, manages moisture, and resists odour through the natural structure of the fibre, which makes it well suited to sustained and variable-intensity activity. Because it performs across a wide range of conditions, a single merino garment can replace several specialised synthetic ones.
Does merino wool smell after exercise?
Far less than synthetic activewear. Merino absorbs sweat into the core of the fibre and holds the odour molecules there until the garment is washed, denying bacteria the surface moisture they need to multiply. As a result, merino garments stay fresh through repeated wear and require fewer washes.
Is merino warmer or cooler than synthetic activewear?
Both, depending on need. Merino is an active fibre that traps warmth when conditions are cold and releases heat when they turn hot, regulating temperature dynamically as conditions change. That responsiveness is why it tends to feel more comfortable than synthetics across a wide range of activity.
How long does merino take to biodegrade?
Buried in soil, 100% merino fabric biodegrades by roughly 95% within about fifteen weeks, returning its nutrients to the earth. Synthetic fibres do not meaningfully biodegrade and can persist for generations.
