There are various opinions on strength training for riders and whether it's necessary etc.
As you'll probably know if you're a follower of mine I'm very much a fan of weight lifting and resistance training and use it with my clients in order to improve their performance.
However that isn't to say I don't believe other forms of training aren't effective. I also use Equipilates and Sports Yoga in classes and with online clients so I definitely feel like they have potential to improve performance too.
Being strong enough to ride is not a set in stone number of weight required to lift.
Strength for riding relates to being strong enough to be in control of your own body when it's on a horse. We need to remain balanced and co-ordinated to give clear aids.
Our bodies are individual as are our horses and what we are trying to achieve with them.
I'm hypermobile so my body is pretty wobbly just on the ground, add to that I've been predominantly riding baby or weaker horses recently means I need to be extra strong to try and remain in control of all of that.
However someone with a much more naturally stable body may not find they need to work so hard to stay in control of their limbs.
Perhaps it's just a fine tuning you require, work on asymmetries and patterning. Pilates may well do that for you.
If it's your mobility and body awareness that's an issue Sports Yoga could help you with that.
Our aim for rider fitness should be mobility, stability and body awareness that then is ingrained enough to maintain under load - i.e on a horse. How you achieve that is actually up to you.