A client wants to use racquetball as her exercise mode to improve her aerobic endurance. What advice you would give her. What will help gain cardiorespiratory benefits. What I found out was – Racquetball is a phenomenal training regimen for building aerobic capacity. I have been in the best shape of my life when I play racquetball regularly. The interval aspect of the game – bursts of intense effort followed by short recovery periods allows a player to build significant aerobic capacity, endurance and expend significant calories. Some research shows that racquetball can burn as much as 600-800 calories per hour. Plus racquetball is playing, it is fun. No one enjoys an hour on the treadmill, but an hour on the racquetball court can easily turn in to 2-3 hours. AND it is social. Many clubs offer leagues or group play. If she isn’t schooled in the sport I suggest she take lessons to learn the basics and good form.