After quietly testing demand last year, ThirdLove is expanding its activewear assortment through new product innovations.
On January 15, the bra brand expanded its TempSync franchise, built around thermoregulating fabric, with an active bra priced at $78 and leggings priced at $88. TempSync uses naturally derived particles infused into fabric to regulate heat and moisture as the body moves. The collection, which is sold direct-to-consumer on ThirdLove’s website, will be promoted through influencers, 3D renderings and editorial-style content focused on product education and lifestyle storytelling.
The activewear launch builds on the success of ThirdLove’s TempSync T-shirt bra, which debuted in June 2025 and introduced the technology to the brand’s core intimates business. “The TempSync collection sold $1 million during the first six weeks of launch, which made it clear to us that it was worth exploring more styles,” co-founder Heidi Zak told Glossy.
TempSync was initially positioned as a means of comfort during hormonal temperature changes, particularly for women navigating perimenopause and menopause. “Women’s bodies change across life stages and even throughout the day,” Zan said. “When we design with that in mind, it shows up in conversion and repeat purchase.”
But, Zak emphasized, “Fit and support are still at the heart of everything we do.”
ThirdLove’s first activewear push came in September 2021, when it launched a 43-piece collection that included sports bras, leggings, tank tops, T-shirts and sweatshirts across three distinct lines — Muse for low-impact movement, Flex for medium-impact and Kinetic for high-impact workouts. Over time, the assortment has evolved but stayed focused on sports bras and leggings, with products like the Kinetic Adjustable Sports Bra and Performance Pocket Legging still featured on the brand’s activewear shop, alongside seamless Flex bras and leggings designed for lower-intensity workouts.
The success of the launches will not be tied to a single KPI, Zak said, adding that the line is meant to bring new women to ThirdLove, to give existing customers more reasons to stay with the brand and to cement ThirdLove as the bra brand “that shows up for women through every moment of life.”
That everyday framing is deliberate in a category crowded with performance-first claims and leggings-led launches.
“Activewear is crowded, but bra fit is our strength,” said co-founder Ra’el Cohen. “Sports bras felt like the right place to begin.”
Cohen noted that while TempSync’s 37.5 technology has long been used in men’s activewear, including base layers and training tops from brands like Adidas and The North Face, it remains relatively underexplored in women’s categories.
As such, the marketing will shine a light on the technology’s temperature-regulating, antimicrobial and moisture-wicking properties. It will also incorporate movement-focused visuals and everyday styling to position the pieces as wardrobe staples rather than gym-only gear.
Activewear leaders including Lululemon and Nike have long used cooling materials, as have traditional apparel brands. For example, Uniqlo and Aritzia have built successful fabric franchises around warmth and comfort, dubbed HeatTech and Cozy Fleece, respectively.
Cohen said early press attention and customer response to TempSync provided reassurance that the expansion will resonate.
Looking ahead, both founders see TempSync as a platform, rather than a one-season experiment. Additional silhouettes are planned for the second quarter, guided by customer testing and feedback. If the active launch resonates, the brand sees an opportunity to expand further into functional, performance-driven apparel while staying rooted in comfort, inclusivity and real-life wearability.
“If it resonates, it gives us room to keep expanding thoughtfully,” Zak said.
Founded in 2013 as a direct-to-consumer lingerie brand, ThirdLove built its early growth around online fit tools and inclusive sizing, scaling to more than $100 million in annual revenue by 2018, according to The Wall Street Journal. In 2019, the company was valued at more than $750 million following a funding round.
