A jump boost is rewarded when you gain a small amount of boost when landing from a jump of any size, whether its a large jump or a small ledge.
In order for you to trigger the jump boost you will need to release the
button once you are airborne and then press it again just as you land.
You can see how many Jump Boosts you have triggered in 'My Stuff - Statistics & Collection' then press
to go to 'My Badges' and scroll down to Jump Boost.
Here's a video demonstration on a Jump Boost
Trigger 49 more to unlock