When choosing workout clothes, performance matters. Whether you're running, lifting, or flowing through yoga, the fabric against your skin impacts comfort, breathability, and endurance. Two of the most common materials in athletic wear—recycled polyester and cotton—are often compared, but they behave very differently when sweat comes into play. Understanding their strengths and weaknesses helps athletes and fitness enthusiasts make smarter choices based on activity type, climate, and personal preference.
Cotton has long been a wardrobe staple for its softness and breathability. Recycled polyester, meanwhile, is gaining popularity for its environmental benefits and technical performance. But when push comes to sweat, which material truly holds up better?
Mechanics of Moisture: How Each Fabric Handles Sweat
Sweat management is critical during physical activity. The body cools itself through evaporation, and clothing that interferes with this process can lead to discomfort, chafing, or overheating. The way a fabric absorbs, retains, and releases moisture determines how effectively it supports thermoregulation.
Cotton is hydrophilic, meaning it readily absorbs water. A cotton t-shirt can absorb up to 27 times its weight in water. While this sounds impressive, in practice, it means the fabric soaks up sweat quickly—and stays wet. During prolonged exercise, damp cotton clings to the skin, creating a heavy, cold layer that hinders movement and increases friction.
Recycled polyester, derived from post-consumer plastic bottles and reprocessed into fibers, behaves differently. It is hydrophobic—resisting water absorption. Instead of soaking up sweat, it pulls moisture to the outer surface of the fabric where it can evaporate more efficiently. This wicking action keeps the skin drier and maintains a lighter feel throughout a workout.
Durability and Longevity Under Stress
Activewear undergoes repeated stretching, abrasion, and washing. Cotton may feel soft initially, but its structural integrity weakens when wet. Wet cotton fibers lose up to 20% of their tensile strength, making them prone to pilling, tearing, and deformation over time—especially in areas like armpits or seams.
In contrast, recycled polyester retains its strength when exposed to moisture. It’s inherently more resilient to repeated stress, UV exposure, and frequent laundering. Because it resists mildew and doesn’t degrade as easily in humid conditions, garments made from recycled polyester typically last longer in an active lifestyle context.
A 2022 study by the Textile Performance Institute found that after 50 wash cycles, cotton-blend workout tops showed significant shrinkage (average 8.3%) and fiber breakdown, while recycled polyester equivalents retained shape and elasticity with only 1.2% dimensional change.
“From a performance standpoint, natural fibers like cotton are not engineered for intense physical output. Synthetic technical fabrics, even when recycled, are designed to move with the body and manage stress.” — Dr. Lena Patel, Material Scientist at SportTech Labs
Comfort and Skin Feel: Breathability vs. Clamminess
Cotton is often praised for breathability and softness. These qualities make it ideal for casual wear or low-sweat environments. However, during high-output sessions, breathability alone isn’t enough. If air can pass through the fabric but the fabric remains soaked, the cooling effect is compromised.
Recycled polyester addresses this with engineered ventilation. Many activewear brands use knitted weaves, mesh panels, and strategic seam placement to enhance airflow. While early versions of polyester were criticized for trapping heat, modern iterations incorporate cooling technologies such as infrared reflectivity, antimicrobial treatments, and micro-channel fibers that improve thermal regulation.
That said, some individuals report that polyester feels “plastic-like” or causes irritation during extended wear. This sensitivity varies by person and fabric blend. Blends combining recycled polyester with natural fibers like merino wool or TENCEL™ can offer a balance—wicking moisture while improving softness and odor resistance.
Real Example: Indoor Cycling Class Experience
Jessica, a spin instructor in Portland, tested both fabrics over a two-week period teaching six classes per week. She wore a 100% cotton tank one week and a recycled polyester blend the next. After her first session in cotton, she noted immediate heaviness and chafing under the arms. By the third class, the shirt had developed an odor despite daily washing. With the recycled polyester top, she reported staying dry even during peak intervals, minimal odor retention, and no fit issues after repeated use.
“I didn’t realize how much my clothes were affecting my energy until I switched,” Jessica said. “The polyester felt lighter, even after back-to-back rides.”
Environmental Impact: Sustainability Beyond Performance
The choice between cotton and recycled polyester isn’t just about function—it’s also ecological. Conventional cotton farming is resource-intensive, requiring vast amounts of water and pesticides. According to the World Resources Institute, producing one kilogram of conventional cotton consumes approximately 10,000 liters of water.
Recycled polyester reduces reliance on virgin petroleum and diverts plastic waste from landfills and oceans. Producing one ton of recycled polyester saves about 5.7 barrels of crude oil and reduces CO₂ emissions by 30–50% compared to virgin polyester.
However, recycled polyester isn’t without environmental trade-offs. It sheds microplastics during washing, which can pollute waterways. To mitigate this, using a microfiber-catching laundry bag and washing less frequently (thanks to odor-resistant finishes) can reduce environmental impact.
Organic cotton offers a middle ground—lower chemical use and improved water stewardship—but still lacks the functional advantages of synthetic performance fabrics during sweaty activities.
Comparison Table: Key Performance Metrics
| Feature | Recycled Polyester | Cotton |
|---|---|---|
| Moisture Wicking | High – actively moves sweat to surface | Low – absorbs and retains sweat |
| Drying Time | Fast (15–30 mins) | Slow (1–2+ hours) |
| Durability (Wet) | High – maintains strength | Reduced – weakens when wet |
| Breathability | Moderate to High (depends on weave) | High (natural fiber structure) |
| Odor Resistance | Good (with antimicrobial treatment) | Poor – traps bacteria and smell |
| Environmental Footprint | Lower carbon, microplastic concern | High water/pesticide use |
| Best For | Running, HIIT, cycling, gym | Yoga, walking, casual wear |
When Cotton Might Still Win
Despite its shortcomings in high-sweat scenarios, cotton has its place in activewear. For low-intensity activities like stretching, Pilates, or leisurely walks, cotton’s softness and natural feel are highly valued. Some people prefer the lack of synthetic materials next to their skin, especially if they have sensitivities to plastics or chemical treatments.
Additionally, cotton is biodegradable under proper conditions, whereas polyester—recycled or not—can take hundreds of years to decompose. For eco-conscious consumers prioritizing end-of-life disposal over performance, this factor carries weight.
Blended options are increasingly popular. A 60/40 mix of cotton and recycled polyester attempts to balance comfort and function. However, these blends often compromise wicking ability, since the cotton component still absorbs moisture and slows drying.
Action Checklist: Choosing the Right Fabric for Your Workout
- ✅ Assess your activity intensity: High sweat = choose recycled polyester
- ✅ Check garment labels: Look for minimum 85% synthetic content for optimal wicking
- ✅ Prioritize fit: Snug (not tight) enhances moisture transfer
- ✅ Wash smart: Use cold water and microfiber filters to extend life and reduce pollution
- ✅ Rotate gear: Allow fabrics to fully dry between uses to prevent odor buildup
- ✅ Consider blends: For moderate activity, blends with TENCEL™ or merino offer comfort + performance
Frequently Asked Questions
Is recycled polyester safe to wear during exercise?
Yes. Recycled polyester used in activewear meets strict safety standards for skin contact. It is non-toxic and often treated with antimicrobial agents to resist odor. Concerns about chemicals are generally unfounded for reputable brands that comply with OEKO-TEX® or bluesign® certifications.
Does cotton cause more body odor than polyester?
Actually, it’s the opposite. While cotton absorbs sweat, it also traps bacteria that thrive in damp environments, leading to persistent smells. Polyester, though hydrophobic, can harbor odor-causing microbes in its fibers unless treated. Modern performance polyesters include silver-ion or Polygiene® treatments that inhibit bacterial growth, making them more odor-resistant overall.
Can I recycle old polyester activewear?
Yes, but not through curbside recycling. Many sportswear brands, including Patagonia and Nike, offer take-back programs where worn-out garments are mechanically or chemically recycled into new fibers. Check manufacturer websites for local drop-off or mail-in options.
Final Verdict: Performance Wins When Sweat Flows
For any activity that raises your heart rate and triggers perspiration, recycled polyester outperforms cotton in nearly every measurable category: moisture management, drying speed, durability, and odor control. While cotton excels in comfort and sustainability under certain conditions, it simply isn’t engineered for the demands of intense physical exertion.
Recycled polyester bridges performance and responsibility—delivering technical benefits while reducing plastic waste. Advances in fabric engineering continue to close the comfort gap, offering softness and flexibility once associated only with natural fibers.
The best choice depends on your routine. For weekend hikes, studio yoga, or light errands, cotton remains a viable, comfortable option. But for training that makes you sweat—running, CrossFit, spinning, or circuit workouts—recycled polyester is the superior performer.
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