So many Chinese send their kids to all type of sports.
All swim competition meets are full well before entry cut off day. Usually, the meet are held in all zones(Bay Area has 4 zones) every 2-3 weeks. Each site can take max about 1000.
If you are talking about the sport activities for adult. There are a lot.
* Table tennis league.
* Basketball.
* Tennis league.
* Bike
* Triathon
* Marathon
* Fishing
* Hiking.
The adult always can find a sport in SF/SJ Bay Area.