BLE could do that too via advertising packets. I don't know if any devices actually do though.

Also the connection process isn't power-prohibitive for BLE, and it doesn't have to take a long time. It's just that most Bluetooth software stacks suck balls. Basically only Apple's is good.

As I recall BLE only supports hosts connecting to 7 peripherals simultaneously which is a bit rubbish, but if you're a gym with some custom ANT+ receiver you can definitely get a custom BLE receiver that can connect to more devices (assuming someone makes such a thing).