The generator kicks in only during the swing phase of a footstep when the muscles are already braking, so it doesn’t take power away from your step and slow you down.

The RUP-inspired "rhythm of the iterations" is in full swing by Construction phase, and this heartbeat has particular relevance to testers.

Thee design, which is still in a prototype phase, cleverly captures the energy of the foot's swing when opposing magnets in each shoe move past each other.