Fastest Warmup for indoor racquet sports

I played a lot of racquet sports and over time I developed back issues and other injuries.

As I was usually rushing after work to play a match, there simply wasn't the time to properly warmup--which of course is a recipe for injury.

The solution I stumbled across was to take a quick jacuzzi (which most racquet clubs have) before the match. It loosened me up better than any stretch. Did it dehydrate me? Probably a bit but I guzzled some water after. I wouldn't recommend this approach for a pro--but I wasn't playing at Wimbledon-I was just playing for fun--and I saw no need to do myself in!