Activewear Beyond Plastic: Natural Fibres, Blends and New Performance Alternatives

Activewear is one of the most intimate clothing categories we own. Leggings, sports bras, base layers and gym sets are worn close to the body, often with sweat, heat and friction — and many people now wear them far beyond the workout.

But activewear is also one of the most synthetic categories in fashion.

In this solo episode of Responsible Fashion Lab, Maria continues the conversation from last week’s episode with Dr Leonardo Trasande on microplastics, plastic-related chemicals and health exposure. This time, the focus is activewear: why performance clothing became so dependent on polyester, nylon and elastane, what those fibres do well, and where the health and environmental concerns begin.

The episode looks at why synthetics dominate performance clothing, why stretch is especially hard to replace, and why sweat-wicking is not the same as breathability. It also explores natural and lower-synthetic alternatives including merino wool, organic cotton, hemp, alpaca and TENCEL™ Lyocell — and where these materials can realistically work.

Maria also looks at blends as the practical middle ground, from merino with nylon for durability to cotton or lyocell with elastane for movement. The episode also explains newer claims such as bio-based elastane, degradable stretch fibres and plant-based nylon — and why “bio-based” does not automatically mean plastic-free, biodegradable or circular.

A practical episode for anyone who wants to understand activewear more clearly: what to wear for different types of movement, what to check on the label, which claims need more detail, and how to buy better without falling for greenwashing.

In this episode:

Why activewear became so synthetic

What polyester, nylon and elastane actually do

Why sweat, heat and friction matter for close-contact clothing

Why sweat-wicking is not the same as breathability

Why stretch is the hardest part to replace