Activewear manufacturers: knits, seams, claims and PFAS rules

What an activewear manufacturer does differently

Leggings, sports bras, training tops and shorts are usually cut from stretch knits, such as nylon or polyester with spandex, and a knit that stretches loads its seams. ASTM's standard practice for stitches and seams says a seam's elasticity should be slightly greater than that of the material it joins^[1]. It says that elasticity depends on the fabric, the seam and stitch type, the stitch density, the thread tension and the thread's own elasticity^[1].

Nearly every item on that list is a choice the sewing floor makes. That is why a shop set up for woven shirts or denim is a different business from an activewear maker, and why the questions that separate them are about stretch:

• Which stitch goes on each seam (flatlock, coverstitch or overlock, for example), and do they run those machines in their own building?
• Which thread do they use on stretch seams, and how do they set stitch density for your fabric?
• Are bonded hems, taped seams or laser-cut edges done in-house or sent out?
• Do they relax knit rolls before cutting, and how do they cut slippery, stretchy fabric without distorting the pieces?
• For prints, which method (sublimation, screen or digital) suits your fiber mix, and will they print a strike-off on the bulk fabric first?

Any step that is sent out adds transit time and one more company between you and the result. Ask for the list of outside steps in writing with the quote. The specs that move a price also differ by piece: a legging turns on opacity, gusset and waistband construction, and a sports bra on support level, straps and cups.

Where performance fabric comes from

The fabric starts as synthetic fiber. USDA's attaché office in China cites national statistics putting the country's output at a record 87.01 million metric tons of synthetic fiber in 2025, up 4.9 percent on 2024^[2]. Hand feel, color consistency, wicking, colorfastness and pilling are set at the knitting and dyeing mill, not on the sewing floor. A factory's fabric source matters as much as its sewing price.

Finished pieces come from a wider map, and the knit heading that names track suits and swimwear covers only part of it. US imports of knit track suits, ski-suits and swimwear (heading 6112) in 2025: $224.4 million from Vietnam and $172.7 million from China, of $651.1 million in all (FOB value)^[3]. Leggings, bras and tops are counted under other headings, so read these figures as a partial view. USDA reports that Vietnam's government plans specialized industrial zones for weaving, knitting, dyeing and finishing, meant to increase fabric production^[4]. A factory there may still be cutting imported fabric, so the fabric's transit can set the ship date.

So ask every factory, in any country, the same four things about the fabric:

• Which mill knits and dyes it, and in which country?
• Is it a stock quality in stock colors, or a development?
• How long does the fabric take to arrive before cutting can start?
• What minimum does the mill set, separately from the factory's own?

A stock quality in the mill's stock colors is the quick route. A custom knit or a lab-dipped color adds development rounds, and the fabric timeline can set your delivery date more than the sewing does.

If a style uses cotton, such as a jogger or a training tee, forced-labor import rules apply to where that cotton was grown. The overseas manufacturing guide covers them, so ask for the yarn and cotton origin in writing.

How customs classifies activewear

The one knit heading with sport garments in its name is heading 6112, for track suits, ski-suits and swimwear, knitted or crocheted^[5]. The woven chapter has its own counterpart. Leggings, tees and tanks are classified by what the garment is, like any other knit. Whether a matching two-piece set counts as a track suit is a call for your customs broker.

Have the broker classify each style from its tech pack before you compare countries, and ask for the duty line that matches its fiber content. Then price each country's quote on landed cost with the import duty guide.

Recycled polyester and nylon: what the label can claim

Under the FTC's Green Guides, a recycled claim is deceptive unless the material was recovered or diverted from the waste stream, during manufacturing (pre-consumer) or after consumer use (post-consumer)^[6]. When a product is only partly recycled, the claim should make clear the amount or percentage, by weight, of recycled content in the finished product^[6].

That puts three questions on the fabric quote. What share of the finished fabric's weight is recycled? Is the feedstock post-consumer, such as bottles or old garments, or pre-consumer industrial waste? And what chain-of-custody certificate from a recycled-content program traces it from the recycler to the spinner to your roll?

A polyester and spandex blend in which only the polyester is recycled is a partly recycled fabric. So the hang tag should state the recycled share by weight, not just the word "recycled".

Wicking and UPF claims need test reports

A performance claim is an advertising claim wherever it appears, on the hang tag or on the product page. The FTC's substantiation policy requires a reasonable basis for advertising claims before they are disseminated^[7]. When the copy says something like "lab tested", the FTC expects at least the advertised level of substantiation^[7].

For a moisture-wicking claim, ask for results under AATCC TM195, a method for measuring, evaluating and classifying the liquid moisture management properties of knitted, woven and nonwoven fabrics^[8]. Ask which grade the fabric reaches, so quotes can be compared. The report should come from an independent lab and name the bulk lot, tested after washing.

For sun protection, the ASTM specification for labeling is ASTM D6603, the labeling specification for UV-protective textiles, which leaves medical-device sun protective clothing to FDA guidance^[9]. It is voluntary, and its labels rest on UV-protection data measured with instruments, so ask that any UPF label follow it. The test route runs through ASTM D6544, which conditions a fabric for two years of simulated seasonal use before UV transmittance testing under AATCC TM183, for labeling under D6603^[10]. Ask whether the fabric was tested relaxed or stretched, because a legging or a rash guard is worn stretched. Keep the copy to the rating and leave out claims about preventing skin disease.

California's PFAS law covers athletic wear

California law bars the sale in the state of new textile articles containing regulated PFAS, from January 1, 2025^[11]. The one delay is for outdoor apparel for severe wet conditions, which has until January 1, 2028, but until then needs a "Made with PFAS chemicals" disclosure, online listings included^[11]. The law's definition of apparel names leggings, leisurewear, athletic wear, sports uniforms and everyday swimwear^[12], so a training range sits inside it.

Regulated PFAS means PFAS added on purpose for a function in the product. The law also sets a measured limit: 100 ppm total organic fluorine in a product or product component from January 1, 2025, and 50 ppm from January 1, 2027^[12]. The component clause reaches trims, elastic and prints, not only the main fabric.

The ban is on selling or offering the goods for sale in the state, so an online store that ships to California buyers should plan for it. Each manufacturer must provide a signed certificate of compliance stating that the article contains no regulated PFAS, to anyone who offers it for sale in the state^[11]. The definition of manufacturer also covers a company the product is made for or distributed by, as identified on the product label under the federal Fair Packaging and Labeling Act^[13]. So the brand named on the label may be the one who signs; settle who signs with your factory and your retailers. Under the same section, a distributor or retailer that relied in good faith on the manufacturer's certificate of compliance is not held in violation^[11]. Expect retailers to ask for that certificate before they list your range.

Water-repellent and stain-resistant finishes are the ones to question first. Get a written statement from the mill and the garment factory that no PFAS is intentionally added, then test the bulk fabric and trims against the lower threshold.

Making activewear in the United States

Ask each US shop whether it buys the fabric or sews fabric you supply, since that decides who carries the mill's minimum. Ask, too, where the performance knit itself is made. An imported fabric has to be disclosed on the label. The FTC gives wording such as “Made in U.S.A. of imported fabric” or “Knitted in U.S.A. of imported yarn”, as a single statement^[14]. The rest of the US label rules are in how to start a clothing brand.

Maker, trading company or blank wholesaler

Companies that call themselves activewear manufacturers include factories that cut and sew, trading companies that place your order with a factory, and wholesalers of finished blanks that you decorate. Each can be the right choice; the problem is not knowing which one you are paying.

A video call from a sewing floor is a start, but a trading company can make one from a partner's floor. Checks that hold up better:

• the registered name and business scope on the license match the quote;
• the plant address on the license is where the sewing happens;
• the bank payee on the proforma invoice is that same company, before any deposit;
• a factory audit report issued in the factory's own name.

A company that cannot name the mill or show the machines may not be the one sewing your order. A company appears on this page when its own website says it makes activewear. The listing does not show who sews in-house, so run these checks on every listed company.

Keep a signed, sealed approved sample as the standard. Before the balance is paid, book a quality inspection at an agreed AQL against that sample.

Then match the company to the route. Blanks are the fastest start but carry someone else's fabric and fit. Private label activewear puts your fabric and colors on a pattern the maker already sews, and full cut and sew gives you your own pattern. OEM and ODM explains how that split shows up in a quote. Ask each maker for its MOQ per style and per color, and whether sizes can be split within it.

Questions buyers ask

How do I start my own activewear brand?

Start with one piece for one kind of training, and settle its fabric early, because the fabric sets the fit, the claims and the lead time. Then write a tech pack with the stretch details: seam types, finished measurements, and how firm the fabric should feel, stated as the spandex share and fabric weight. Sample in the bulk fabric and get test reports for every claim you plan to print.

What to put in your request

Send the fiber content and fabric weight, or the mill's quality code if you have one. Add the colorways, the size run and the quantity per style and color. Say whether any style is sized for children, which brings the testing and tracking-label rules in the clothing brand guide. List any finishes or claims you plan to print, and attach a tech pack or a reference garment.

Minimums and lead times are set per manufacturer; where a listed company publishes its minimum, this page shows it with the date it was checked. Get the sample cost and the bulk lead time in weeks in writing with every quote, along with its fabric mill and Incoterms rule. We introduce you to activewear manufacturers that fit, each one named, overseas first or in the US if you ask. Once we offer it, manufacturers can pay for a Featured placement, labelled as paid. Paying for placement does not change who we shortlist, though a Featured manufacturer may receive your details sooner if you agree to share them, as how it works explains.