My sister complained of similar problems when she started getting into shooting her carry pistol regularly.
In addition to the advice about leaning foward in your shooting stance, I would advise also doing some stretches before shooting, as you would before any physical activity. And some stretching afterwards as part of a cool down.
NRA Life Member
Big Sister: "Everyone in America is fine with the .30-30, except Mack. He has to shoot that .35 because that extra point zero fives inches will matter on Bigfoot."