Gyms that were forced to close brick-and-mortar locations during the pandemic are now trying to survive by holding classes outdoors. Trainers are setting up open-air sessions in parks, parking lots and on rooftops, and some tell CNBC that these classes are helping grow their customer bases during a time of severe contraction for the industry. Several chains, like Gold’s Gym and 24 Hour Fitness, have declared bankruptcy during the crisis. Outdoor workouts also provide an extra stream of revenue on top of less-profitable virtual classes.