With veins popping along swollen biceps, a roughly muscled Mark Wahlberg stares at the camera, above a quote that reads, “I fell in love with the energy. I fell in love with the community”. Dressed in a skin tight white t-shirt, the image of the Hollywood actor appears in the IPO documents for F45, the fitness group with a cultish following that was valued at $1.4 billion when it floated on the New York Stock Exchange last year. While other fitness groups had taken a hammering during Covid, F45 seemed to defy the odds. The IPO raised $279 million for…