I sometimes get a sore/tight left QL (quadratus lumborum) after playing - I'm a rightie. The physiotherapists I've seen have all confirmed it's the QL, but unfortunately none of them know much about tennis so I haven't been able to get any advice other than "stretch it before and after". It's a bit of a problem because a tight QL can cause sacro-iliac issues, which I unfortunately know about all too well...
Does anyone here have the same problem? Are there any particular shots/techniques it's associated with, and is there anything you'd recommend to get rid of the soreness/tightness? The only stretch that I've been recommended looks similar to the first picture on this page:
except it's done standing.
Any knowledgeable and productive insight would be most welcome!