Rein contact symmetry is a massive thing. It can affect your horse's straightness, how well you apply aids and also how well he is able to come into a contact.
A good rein contact comes from stable shoulders and back,if the shoulders aren’t stable the biceps, chest and forearms will brace to hold the rein which will create tension. Soft hands come from stable shoulders.
Of course it doesn’t just stop there…..we want them to be as equally stable as possible-no good having a great right hand and a flappy left one!
Working on your shoulder stability off horse is a great idea.
In the gym things like Single arm rows either kneeling on a bench or standing using the cable are great. It is important to slow the move me down and really feel the shoulder and back working rather than letting the biceps do the work.
Kettlebell or Dumbell Windmills are a great shoulder stabiliser, as are bottom up kettle bell press-they’re tricky too!
At home with a band, or in the gym with a cable, single arm dumbwaiters are great for learning to take the arm away without losing the stability.
Sometimes I like to do these exercises in a half squat stance or standing on a wobble board, sat on a gym ball etc. The reason I like to add something else Is that I find I can concentrate on my shoulders on their own but add in a horse and it falls to pieces; so I need to learn to control my shoulders whilst using other muscles.
On horse I find trying to focus on keeping your elbows equal helps to maintain an equal amount of contact in each arm.
Also “closing your back armpit “ switches on the back muscles to further stabilise the shoulder area.
Try these out and let me know if you can feel the difference.