Most riders I see don’t need extra range in their inner thigh, if you’re able to get on your horse you’ve got all the range you need-admittedly how much range that is depends on what you’re riding-Cobs aren’t the same as Arabs!
Either way, you don’t need to be able to do the splits to ride better.
I also find most riders have plenty of strength in their inner thighs, however what I do find is a problem is the ability to control how much “On” or “Off” they have.
It’s either all on or all off.
My riders have found it helpful to work on dialling up and dialling down their inner thigh muscles. Then when you’re riding you can give only the amount of the aid required and if you’re really cool, inner thigh aids independently!
In the classic inner thigh exercise – Side lying lifting the lower leg, we often tense the leg, make it rigid and lift from there. Classic all or nothing!
Try the same exercise and make the leg soft, make it feel as light as possible as you lift it up and down. Try upping the inner thigh activation without creating tension in the leg, can you dial it up and dial it down?
Sitting on a gym ball can you turn your body left and right without at least one of your thighs clamping on or increasing in tension? Of course, you may need to increase activation of your inner thigh to perform a movement but if you are aware of how much or how little you are applying those aids will be much more accurate and clearer to your horse.
Next time you ride, can you take your inner thigh completely away from the saddle. How softly can you apply it? Can you apply one whilst fully removing the other?
In your on and off horse training start to bring awareness to your inner thighs and start to use them with more of a gear system as opposed to an all on or all off system.