The workout regime at F45 Training is designed to challenge the body, but also seems to toughen the mind. Every day, tens of thousands of fitness enthusiasts in cities from Anchorage, Alaska, to Johannesburg descend on identically laid-out gyms where, for 45 excruciating minutes, they tackle a circuit of high-intensity exercises that burn calories and build muscle. “When you leave this studio,” the Hollywood movie star Mark Wahlberg said after a recent pre-dawn session, “you feel like you can accomplish anything.”

Wahlberg, who invested in the gym brand in 2019, has sold nearly $13mn worth of shares this year and remains one of the largest shareholders. The company completed an initial public offering valuing it at $1.4bn last year after a lockdown-defying growth sprint that marked a stark contrast with YogaWorks, Town Sports International and other once-ubiquitous fitness operators that entered bankruptcy during the coronavirus pandemic. By the end of last year, F45 counted nearly 1,800 gyms in dozens of countries, and had signed contracts with local franchise operators to open about 1,500 more.

Mark’s not going to get on a plane and go to your grand opening. But if you’re opening a gym in Las Vegas, he’ll definitely show up if he’s already there

Yet just as the broader gym industry is recovering, F45 has run aground. The company’s shares, which peaked at more than $17 a year ago, have recently traded as low as $1.35 and closed at $2.23 on Wednesday. In an unscheduled announcement last month, the chain said it was parting company with chief executive Adam Gilchrist, firing most of its workforce, and cutting by about two-thirds the number of new gyms it expects to open this year.