This is the Kickstarter campaign for the $400+ HoverGlide backpack from Lightning Packs. The bags contain"patented 'Suspended Load Technology' (SLT), which allows the carried load to seamlessly move up and down with respect to the person walking or running. This keeps the load at a constant height with respect to the ground." MAGIKA. Of course you could buy a lot of JanSports for $400. Or hire a child to carry your bag for you. That's what I did with my brother. "Wait -- you're paying me?" Only in noogies.
While standing still, a 50 lb load in your backpack exerts 50 lbs of force (static weight). This changes when you walk or run, where the peak force exerted on you can be up to 3x the weight you are carrying. Suddenly a 50lb pack can put as much force on the body and joints as if it weighed 150 lbs. With the movement of SLT, this additional force over and above the static weight can be reduced by as much as 86%!
Admittedly, if you spend the majority of your life wearing a backpack this might be a reasonable investment. Personally, I only wear a backpack on the walk to and from the beer store and consider the weight of a 12-pack my workout for the day. I'm kind of a fitness buff like that. "You're panting just sitting at your computer." I should lie down.
Keep going for a couple videos.
Thanks to Erik L, who just pushes an all-terrain shopping cart instead.