whoever thought of this must be really bad at physics. When you jump and hits the ground on your legs, when your legs hit the ground, the G-force applies from falling is neutralized by the ground. In fact it could make you shorter since it is pushing you body together. G-force from the top while falling presses your lower body inward as you hits the ground. Instead stretching could help you grow taller, since it is pulling your body from inward to outward.

put a simple simulation to the test, take a sponge and keep pushing it in repeatedly for a few days and see if it gone smaller.
Take another sponge and stretch it for a few days and see if it gone longer
XD

hope this helps