You actually want foam blocks that don't have much give as humans tend to be pretty heavy. But you also want lot of them. I think in circus school I was one time there was over meter of this stuff.
Either the foam will compress, or it won't compress and the energy will 'dissipate' in the human body.
In this case, we had foam that appeared non-compressable with sharp points that hit on the back. This feels like a level of stupid that it takes an MBA to come up with.