To consider Wado Ryu based Karate when I have 'mechanical' backpain?

I have been warned off riding horses, but am still not sure if my GP
is just being over protective. I've been x-rayed and there is no disk
damage - just general wear and tear according to my gp.

I swim 3 x a week and am fine with that, the only time i 'ache' these
days is during the night or if i sit still for too long.

does anyone practise karate that has or has had back pain?

I have signed my 2 girls up this week and would love to join them..
just don't know what i should avoid if anything. I'm not sure i'll
ever compete just for fitness, personal enjoyment and self defence. :)

Thanks all