Chances are, your favorite exercise attire is synthetic, made from petroleum-based fibers like nylon, spandex and polyester. Materials that don’t exactly scream “climate friendly.”
Natural fibers have issues, too: Growing cotton can use huge amounts of water and pesticides, the sheep that give us wool emit methane, and processing bamboo can produce a lot of pollution. Altogether, the apparel and footwear industries account for more than 8 percent of global greenhouse gas emissions.
So if you want to keep your body fit while also keeping the planet healthy, what should you do?
Consider recycled fibers
There’s a lot of plastic polluting our lands and waters. Some companies have capitalized on that, melting down plastic waste and extruding it into yarn.
Karen Leonas, a professor of textile sciences at North Carolina State University, said those materials could be a good choice for workout clothes.
“Any time you can find something that contains recycled fibers, that’s definitely a plus,” she said. “Whether you’re looking at climate, water, solid waste or even social sustainability issues.”
Lewis Perkins, president of the nonprofit Apparel Impact Institute, also said he liked recycled fibers. But he cautioned that they’re a “transitional solution,” as he believes the ultimate goal should be reducing the prevalence of single-use plastic in the first place.
Look for certifications
If you’re hoping for a blanket answer about which materials are good or bad, Dr. Leonas said, it’s not that simple. “ I can be the devil’s advocate on any fiber,” she said. “There are trade-offs with all of it.”
As an example, she compared polyester and cotton. While polyester is made from petroleum, its production uses little water and no pesticides or fertilizers. It also holds up better than cotton when it’s recycled.
You might be thinking: But what about wool? Bamboo? Dr. Leonas noted that raising sheep produces methane and nitrous oxide. And, there are concerns about animal welfare. The processing of bamboo can release toxic chemicals into the environment. And some recycled fabrics can still shed microplastics.
So, rather than searching for a unicorn fabric, Mr. Perkins suggested seeking out the “most ethical” version of the fabric that meets your performance needs. To do so, he looks for third-party certifications like OEKO-TEX, bluesign or Global Recycled Standard.
“That’s a way to know that this fabric — whether it’s polyester, which has its problems, or cotton, which has its problems — has been verified as the best available version of that material,” Mr. Perkins said.
If you’re worried about so-called forever chemicals, some of these certifications check for that, too. But you should also note that California and New York recently banned the sale of apparel containing intentionally-added PFAS.
Find brands you trust
Another strategy is sticking to brands that have strong sustainability commitments.
To reduce the likelihood of greenwashing, Mr. Perkins said you can check if a company’s been certified as a B Corp. That means it must meet certain social and environmental standards. You can also visit a company’s sustainability page to see if it’s involved in any collaborations, such as the Textile Exchange or the United Nations’ Fashion Charter.
Such efforts “usually don’t last very long if they’re not credible,” Mr. Perkins said. “Because the companies don’t want to invest money in something that’s going to be a liability to them when somebody finds out it’s not doing real work.”
Another good sign, Mr. Perkins said, is if a company offers a repair or recycling program for its clothing.
Of course, buying your workout gear secondhand is a solid plan, too. Just try not to think about the sweat factor.
Make it last
If all that sounds like too much work, don’t fret. There’s one simple step that may make the biggest difference of all: Choose items you’ll wear for years.
Karen Pearson, a professor of chemistry at the Fashion Institute of Technology in New York City and leader of the school’s sustainability efforts, works out in yoga pants nearly every day. She’s loyal to one brand that she knows will perform well and look good for years and years.
A garment’s “functionality and performance over a long period of time,” she said, “turns out to be the thing that really helps change its impact on the environment.” Dr. Pearson cited a British report that suggests that extending the life of a garment for just nine months can reduce its carbon emissions.
To find items that will last, choose classic colors and styles that won’t soon go out of fashion. Check the seams, too: Dr. Pearson said products that are seamless, or that have reinforced seams or larger seam allowances, are more durable.
And, once you purchase a product, take care of it. Dr. Pearson hang-dries her yoga pants, which helps them last longer and also avoids greenhouse gas emissions from the dryer.
“ I want a few really good quality pieces that are made in a responsible way, that will stay in my closet for a long time and not get replaced,” she said.
