large group of people exercising in a spacious, indoor facility

large group of people exercising in a spacious, indoor facility. Most of the participants are lifting black medicine balls above their heads. Many are shirtless. The floor is marked with grid lines. Spectators are watching and filming the exercise session. The building has a high ceiling with exposed metal beams and fluorescent lighting. Speakers are mounted to the ceiling, and monitors are affixed to the exercise equipment. A large yellow warning sign with an electrical symbol is visible on a structural element in the foreground.