R&D Update: Our search for better natural fibre activewear for running

From day one, our goal has been to create high-performance running apparel using carefully selected natural fibres wherever possible.

The challenge is that running places unique demands on fabric.

Running tights and sports bras need to manage moisture, provide support, recover after stretching, remain comfortable against the skin, withstand repeated wear and washing, and ideally minimise odour.

Finding a natural fibre that can do all of this is challenging.

Over the past year, we've been researching and sourcing fabrics from around the world, including here in New Zealand. We've been testing different fibre compositions, fabric weights, elastane percentages and knit structures to better understand what works and what doesn't.

Here is where our research currently stands.

TENCEL™ Lyocell for Activewear

Of all the fabrics we've tested so far, TENCEL™ Lyocell blends are currently among the most promising. We just haven't quite found the exact density and level of compression we're completely happy with yet.

TENCEL™ is a branded lyocell fibre made from sustainably sourced wood pulp, most commonly eucalyptus.

What makes it particularly interesting for running apparel is its moisture-management capabilities combined with exceptional softness.

The fibre contains microscopic fibrils that help transport moisture away from the skin and distribute it throughout the fabric. This helps moisture evaporate more efficiently and can create a cooling sensation during movement.

Unlike many synthetic fabrics, TENCEL™ also tends to remain comfortable during extended wear and does not hold odour as readily.

When blended with elastane, TENCEL™ is showing strong potential for garments that require both stretch and support.

The challenge we are currently facing is ensuring garments remain truly squat-proof while maintaining durability.

One fabric we sourced was performing beautifully in this regard. However, the knit structure was catching in manufacturing machinery and also showed signs of abrasion in high-friction areas over time. Unfortunately, that particular fabric was eventually discontinued.

We're continuing to test different fabric weights, elastane percentages and knit constructions, but at this stage TENCEL™ remains one of the leading contenders in our development process.

Bamboo Lyocell: Not the Same as Traditional Bamboo Fabric

Bamboo appears to be one of the most misunderstood fibres in the sustainable apparel space.

From our research, bamboo can be a highly promising fibre when produced using a lyocell process. This distinction is important because bamboo lyocell and bamboo viscose are not the same thing.

Traditional bamboo viscose relies on a chemical-intensive manufacturing process that converts the hard structure of bamboo into a regenerated cellulose fibre.

Bamboo lyocell, on the other hand, is produced using a closed-loop manufacturing process where the solvent used during production is largely recovered and reused.

While it is still a processed fibre, the manufacturing process is generally considered an improvement over conventional viscose production.

Like TENCEL™, bamboo lyocell offers softness, moisture management and comfort against the skin.

When blended with approximately 20% elastane, it is showing encouraging results in our testing for running tights and other performance-focused garments.

At this stage, bamboo lyocell sits alongside TENCEL™ as one of our strongest candidates for future development.

Organic Cotton for Activewear

Organic cotton remains one of the most trusted natural fibres available.

It's comfortable, breathable and widely understood by consumers.

However, based on our testing so far, we are not convinced it is the best option for high-performance running tights.

Compared with some of the regenerated cellulose fibres we're exploring, cotton tends to retain moisture for longer periods.

While this may not be an issue for everyday wear, it becomes more noticeable during longer or more intense runs, where moisture accumulation can increase garment weight and reduce comfort.

We've also found that organic cotton does not "snap back" as effectively as some other fibres, even when blended with elastane. This can make it more challenging to maintain long-term garment shape and compression.

Where organic cotton continues to shine is in lower-impact movement such as yoga, walking and recovery sessions.

We're particularly interested in using it for t-shirts, crops and lifestyle recovery pieces where softness and comfort are the primary objectives.

Merino Wool Running Apparel

Merino wool is our next major testing candidate and is produced right here in New Zealand.

Naturally temperature-regulating, odour-resistant and capable of managing moisture, merino has already proven itself in outdoor apparel for decades.

For runners, the ability to remain comfortable across a wide range of temperatures is particularly appealing.

Merino can help keep you warm in cooler conditions while remaining breathable enough for movement.

The challenge lies in creating the level of support and compression required for performance-focused running tights and sports bras.

This is where knit engineering becomes incredibly important, along with finding the right blend of elastane.

We're excited to continue exploring how different knit structures, yarn constructions and elastane percentages can help unlock merino's full potential in fitted running garments.

While we're still early in the process, we're particularly excited about what merino could offer.

Why We Love Hemp

Hemp continues to be one of our favourite natural fibres, and we believe it is quite underestimated in the activewear space.

From a sustainability standpoint, it requires relatively little water to grow. It is also naturally durable and tends to wear well over time.

Historically, hemp fabrics were often associated with a coarse or rigid feel. Modern processing techniques have significantly improved softness and wearability.

Like organic cotton, we currently see hemp as being particularly well suited to looser garments.

That said, when combined with the right knit structures and carefully selected elastane blends, hemp could potentially become an interesting option for sports bras where durability and support are essential.

We're receiving our first hemp-blend sports bra sample next week and are excited to see how it performs.

Corn-Based Fibres, SeaCell and Other Sustainable Textile Innovations

The sustainable textile industry is evolving rapidly.

Many brands are now exploring alternatives derived from corn, banana leaves, sugarcane, seaweed and other plant sources as potential replacements for conventional synthetic fibres.

While these innovations are exciting, we're approaching them with curiosity and an open mind. Just because a fibre originates from a plant does not automatically make it the most sustainable, healthy, durable or practical option.

Questions around land use, manufacturing processes, chemical inputs, durability and end-of-life outcomes all need to be considered.

A fibre that performs poorly and requires frequent replacement may not ultimately be the better solution.

I also personally purchased a pair of cornstarch-based tights over a year ago and was not satisfied with either the compression or the feel against my skin. To me, they felt unnatural and scratchy.

Of course, that is only one garment and one experience, but it reinforced the importance of testing products thoroughly rather than relying solely on marketing claims.

Where Our Natural Fibre Activewear Research Stands Today

At this stage of our research, TENCEL™ and bamboo lyocell blends combined with elastane are showing the strongest results for running-specific garments that require both moisture management and support.

Merino wool remains firmly on our radar as we continue exploring advanced knit structures that may help deliver greater performance.

Organic cotton and hemp remain fibres we genuinely love, particularly for looser-fitting garments and lower-impact movement. Ensuring these fibres are GOTS-certified is also extremely important to us.

Final Thoughts

Creating garments that are both comfortable and truly fit for purpose is extremely important to us.

We will continue to move as slowly as necessary to find the best possible fabrics and carry out thorough garment testing before going into production.

Our job is to keep asking questions, keep testing and remain transparent about what we're learning along the way.

We'll continue sharing our findings as our research develops.