HIIT is an independent company.

British activewear brand created within the Arcadia Group in approximately 2018, positioned around high-intensity interval training and athleisure. HIIT was acquired by ASOS alongside Topshop, Topman, and Miss Selfridge from the Arcadia Group administration in February 2021 for the combined £265 million. It operates as an ASOS-owned activewear brand sold exclusively online.