You really just have to watch the demonstration video to fully grasp what’s going on with this backpack…do so and then read on:
Pretty incredible right? These “floating backpacks” by Lightning Packs that supposedly reduce impact forces up to 86%. 
Here’s a bit from the company’s website:
“Our ergonomic backpacks use an innovative pulley system to reduce impact forces on the user by 80 to 90%, which reduces exertion and injury.
We first designed, built under contract, and delivered a series of ergonomic and electricity-generating backpacks for personnel of the United States Army and Marine Corps. The ergonomic benefits of our design have been field-tested and approved by soldiers themselves.
We now want to offer our Ergonomic Lightningpacks for individuals seeking higher performance while on the move. Our company is ready to produce a pack that enables quicker, easier travel while reducing back pain and injury. With your help, we can make that happen.
Lightning Packs, LLC, was founded by Dr. Lawrence Rome, a muscle physiology expert and professor at the University of Pennsylvania. Using technology that Rome invented and patented, the company designs and creates innovative backpacks that generate electricity and reduce stress on the body.”
