Hoover-ball was played by teams of 2-4 players with a six-pound medicine ball over a net eight feet high on a court similar to one used for tennis. The game was scored exactly like tennis, and played in similar fashion. The server throws the ball. The opponent must catch it on the fly and immediately return it, attempting to put it where it cannot be reached and returned. The side that misses the ball or throws it out of bounds loses the point.

"Stopping a six-pound ball with steam back of it, returning it with similar steam, is not pink-tea stuff," DuPuy wrote. "Dr. Boone estimates that as much beneficial exercise is obtained from half an hour of it (Hoover-ball) as from three times as much tennis or six times as much golf." 

Rules

• Points are scored when a team: fails to catch the return, fails to return the ball across the net, returns the ball out of bounds. 
• The ball is served from the back line. 
• The serve is rotated among one team until the game is won. Teams alternate serving after each game. 
• The ball must be caught on the fly and immediately returned from the point it was caught. There is no running with the ball or passing to teammates. 
• Each team's court is divided in half. A ball returned from the front half of your court must be returned to the back half of your opponent's court. If the ball doesn't reach the back court, the opponent is awarded the point. 
• A ball that hits the out-of-bounds line is a good return. 
• A player who catches the ball out-of-bounds, or is carried out-of-bounds by the force of the ball, may return in-bounds before the return. 
• A ball that hits the net on its way over is a live ball. (If it was thrown from the front court, it must reach the opponent's back court to be good.) 
• Teams may substitute at dead ball situations. 
• Women serve from the mid-court line. 
• Women may pass once before a return. 
• Women may return the ball to any area of the opponent's court. 
  Good sportsmanship is required. Points in dispute are played over.