The world's trusted guide to sustainable and ethical fashion

The world's trusted guide to sustainable and ethical fashion

Itchy and Hot, or Sweat-Wicking and Comfy? Sustainable Wool Activewear Is On the Rise

Wearing wool can be a challenge, even on a cold winter’s day. We all have memories of suffering through the holidays in our itchy sweaters. So to suggest wearing close-fitting woolen activewear during a hard, sweaty workout? Unthinkable.

And yet, many brands are starting to release active woolen wear, including Icebreaker, an outdoor apparel company that champions sustainable practices and began offering woolen fitness wear in 1996. Merino wool has been gaining popularity as a ‘next-to-skin’ fabric, with many brands using it to make socks, underwear, and, you guessed it, activewear. 

Polyester, the dominant outdoor and athletic material and the most widely used fiber in the world, is made from fossil fuels, and doesn’t biodegrade.

But companies like Icebreaker are choosing wool for reasons other than avoiding synthetic microfiber pollution. They believe that, done right, woolen activewear can be more comfortable, sweatproof, and odor-resistant than its synthetic competition, while being the clear eco-friendly choice. You may be a skeptic, but stick with us—by the end, you might be ready to jump into the latest wool activewear.

Wool Biodegrades

Wool is, of course, obtained as natural fiber from sheep. Studies have repeatedly shown that synthetic materials, which are made of plastic polymers, take many hundreds of years to break down in the environment, releasing microfibers along the way. 

Wool has no such issue. 

Stewart Collie, PhD, the science team leader for bioproduct and fibre technology at AgResearch (a New Zealand Crown Research Institute lab), compared the biodegradation of standard household fibers in a marine environment and found that treated wool degraded at 67% of the rate of the control group of cellulose pulp. Meanwhile, synthetic materials (nylon, polyester, and polypropylene) degraded up to 10 times slower. In fact, nylon degraded at 0.8% of the rate of cellulose pulp. 

“Polyester, nylon, [and] polypropylene didn’t biodegrade, whereas the wool materials did,” Stewart says. “They were well on the way to full biodegradation by the completion of that test.”

This doesn’t paint a pretty picture. It means that microfibers that are released into the waterways each time we wash our favorite yoga pants won’t be going away any time soon.

“The experiments were designed to try and understand what happens to microfibers once they end up in the environment,” Dr. Stewart Collie explains, “They’re everywhere… every week you find a study that tells you that they [microfiber] have been found somewhere else.”

It’s important to base our decisions upon hard science, but it’s also common sense.

“The reality is that we know that fur from animals, fiber from sheep, and feathers from birds … don’t stay in the environment forever because otherwise, over the millions of years in which life has been on the planet, we’d be piled high in the material. And that’s clearly not the case. So we know that nature runs a circular system. So a lot of the research that we’ve done is just understanding the mechanisms and being able to understand more about the rates of which things occur and the influence that we have when we convert them into textile materials.”

In Stewart’s study, they tested untreated wool against ‘machine washable wool’, which was treated with a crosslinked polyamide. Surprisingly, the study showed that this polyamide contributed to an increased rate of degradation in a marine environment. It was hypothesized the treatment may have led to a reduction in the wool’s cuticle, leaving it vulnerable to microbial decay not found in your regular washing cycle. Regardless, both types of wool tested degraded when exposed to the marine environment and at a far more rapid rate than any of the polymer-based fabrics tested. 

So, according to our expert, the verdict is in. Woolen activewear is far less detrimental to the marine environment, but what about how it feels?

Why Synthetic Fabrics Can Be Itchy

Depending on how sensitive your skin is, any textile can irritate. And, counter to popular belief, you’re more likely to get ‘textile dermatitis’ from synthetic materials. 

This occurs because synthetic fabrics are not as breathable as wool, making us sweat more. Unlike wool, which can be itchy as soon as you get dressed, textile dermatitis from synthetics is more likely to occur after a workout.

Synthetic fabrics also make use of ‘disperse dyes’. Disperse dyes are synthetic dye compounds used specifically for dyeing synthetic materials such as polyester and nylon and have been shown to be chemical sensitizers, meaning they irritate many people when exposed repeatedly. This is especially true of the dyes used to make black and blue fabric, which just so happens to be an extremely popular color of choice for activewear. These dyes are also more likely to be released when we sweat, making them very poor choices for activewear. All of this is to say that these dyes are the most prevalent cause of all textile-related allergic contact dermatitis.

Lynn M. Fowler, BSN, RN, has studied how wool affected dermatitis. “Pure wool, when dyed, holds the color tightly and little is able to be released from the wool. Dye can cause allergies when used on clothing that is a mixture [of] synthetic materials, as they are not generally color fast.”

Stewart Collie’s team at AgResearch also set out to test people’s reactions to polyester and wool. The initial data shows the subject’s skin favored wool over synthetic fiber. The sixteen volunteers spent the day wearing close-fitting base-layer shirts made from merino wool with a polyester patch on their back. The early data indicated that the wool area supported healthy skin, while the polyester patch had a drying effect with some inflammation. 

Synthetic fabrics don’t biodegrade in our environment, and they can be just as—if not more—irritating. So many of us are looking for a more sustainable alternative without sacrificing comfort. So along comes our knight in wooly armor! If only it weren’t so itchy… (or is it?)

Avoiding That Wool Itch

Wool can irritate the skin for two reasons; it can cause an allergic reaction in a minority of people, and secondarily, it can cause a very pedestrian, physical itch in others.

Evidence suggests that wool allergies have increased between 2004 to 2015. This reaction is caused by your immune system working overtime when coming into contact with wool, specifically lanolin, the waxy substance sheep produce to weatherproof their wool. However, despite the increase, less than 2% of people tested for wool allergy as of 2015 had a legitimate contact allergy to lanolin. 

For most of us, we experience something a little less drastic. One study looking at the causes of irritation calls this irritant contact dermatitis. And it turns out it’s dependent on the thickness of the wool fibers. 

The wool fiber thickness is determined in part by the breed of sheep and its age. Lambs having finer wool than an older sheep. Garments made from thicker yarns in the range of 30 to 32 microns, which stimulate your pruriceptors, or, ‘itch detectors’. But these receptors are only so sensitive—softer materials with finer fibers can bypass them altogether, skipping the itch.

“There will always be the odd individual who is more sensitive than others,” Dr. Stewart Collie says. “We all vary in [the] extent to which we have that sensitivity. Once you get below a threshold—probably around 17, 18-micron fiber diameter, it’s likely to be comfortable for everyone.”

The Merino sheep, which originated in Spain and is a popular breed in Australia, New Zealand, and South Africa, produces wool fiber with a naturally lower micron count of 18.9, well below the itch threshold of 30 microns.

You get what you pay for in the wool industry—the finer the thread, the more expensive it is. Merino is more costly than standard wool as it has a finer yarn, meaning more wool is required to create the same garments. 

Why Merino Wool Is Perfect for Activewear

Merino wool is also naturally odor-resistant due to the fiber’s unique properties. This odor control happens because wool can absorb large amounts of water, unlike hydrophobic synthetics. The absorption capabilities of wool are twice as much as standard cotton, and a staggering thirty times more than polyester.

By absorbing the moisture away from the skin, wool discourages bacterial growth. The makeup of wool fibers allows the fabric to lock this moisture away, releasing this moisture (and the odor) when we wash our clothes. This characteristic of wool means that we don’t need to wash our garments after every wear. Hanging your merino clothes on a hanger overnight to air out can keep them fresh.

Wool also helps with temperature regulation by helping you stay warm while remaining breathable, making it perfect for winter sports and performance garments. 

Wool is also naturally elastic. This means wool exercise clothing can stretch with us while we work out. This elasticity also means wool keeps its shape long-term, making it an excellent investment for your exercise needs. 

How Do You Wash and Care for Merino Wool Activewear?

Although merino wool clothing requires a little extra care, the process is simple once you know what to look for. Firstly, check the garment’s care tag suggestions as each item and manufacturer differ. Machine washable wool will have a note on the garment tag indicating that you can put through the garment in the washing machine.

The most important thing to remember when washing wool is to avoid heat as it will shrink your garments. This includes both skipping hot water cycles and tumble dryers. 

Additionally, you can turn your wool garments inside out when washing them, use a gentle cycle, and use a mild and natural detergent. This will help keep your garments soft and comfortable.

Merino Wool Brands We Love

Luckily for you, there are plenty of options if you are looking for merino wool activewear. We hope wool becomes your new, favorite, (unexpectedly soft) fabric.


Icebreaker is a New Zealand-based brand specializing in merino wool casualwear, activewear, workwear, and even underwear. Icebreaker garments have a micron rating of between 15.5 and 19, to cut down on any itching. 

Icebreaker Merino Wool Activewear


Patagonia is a brand that doesn’t need an introduction. A pioneer in the sustainable space, Patagonia offers merino wool socks, active tops, beanies, and outerwear. Patagonia works tirelessly to ensure its supply chain is run in an ethical manner, and the clothing manufacturers work under fair working conditions and is a 1% for the Planet member.

Patagonia Merino Wool Socks


Fjallraven is a Swedish brand that uses wool and recycled wool to make innovative products, including t-shirts, leggings, bags, jackets, sweaters, and beanies for the cooler weather. 

Merino Wool Activewear


Nagnata is an Australian fashion and activewear brand that uses Australian wool as a key part of its products to help support the Australian wool industry. Nagnata offers bralettes, shorts, leggings, tops, bodysuits, and loungewear.

Nagnata Merino Wool Activewear


Allbirds is a New Zealand based brand that started its journey by creating sneakers out of wool. Allbirds also offer wool bralettes, leggings, tops, and other active pieces. Allbirds is also both certified B-corp and carbon neutral. 

Allbirds Merino Wool Sneaker



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