 Most 2010-era health clubs offer group exercise classes that are conducted by certified fitness instructors or trainers.Many types of group exercise classes exist, but generally these include classes based on aerobics, cycling (spinning), boxing or martial arts, high intensity training, step yoga, regular yoga and hot (Bikram) yoga, pilates, muscle training, stretching, and self-defense classes such as Krav Maga and Brazilian jiu-jitsu.Health clubs with swimming pools often offer aqua aerobics classes.