We all know how perfect equitation over a fence is suppossed to look. Especially that lower leg. And although it will occassionally slip back it shouldn't be a habit.
What about when your just flatting around? I mean, it doesn't matter if your warming up to jump, doing a dressage test, trail riding, barrel racing, ect... A stable lower leg trancends discipline.
A stable lower leg means more balance and clearer communication.
So why does the lower leg tend to slip back or bounce about?
If I said a lack of strength one might think just gripping more is the answer. Not really though. Although a little more engagement in your calves will help. But if you squeeze too much it can be confusing especially with a sensitive ride as squeezing more means "GO" to the horse.
We condition our horses muscles to do what is needed. We start them off jumping low before working up. We school them to shorten and lengthen the trot before asking for extended or collected trot. We do transition work so that they develop and uphill strikeoff. You get the point. We don't make them gain strength for a strenuous movement by having them just do it. That could even lead to injury let alone the confusion and frustration. Instead we have them build strength to accomplish it properly when they are ready.
It's the same with us.
Why not increase your calf strength with a few exercises rather then just assume that jumping more or riding more will work.
Trust me I had legs that would slip back over jumps. We all know how far forward and off balance that can pitch you. It can be dangerous. Same goes for a lack of clear communication due to a bouncing leg on a green or sensitive mount.
It wasn't untill I strengthened my calves through exercise that I could consistantly keep my lower leg underneath me.
Here are some exercises to help.