Why do you start to walk like an elderly person at the age of 25?

Eline van der Kruk is an assistant professor (tenure track) at the department of Biomechanical Engineering at the faculty of ME. Her research focusses on Biomechanical Optimizations in Daily life, Exercise, and Sports. 

In this video from Universiteit van Nederland, Eline explains why you start walking like an elderly person at the age of 25:

https://www.universiteitvannederland.nl/college/waarom-begin-je-vanaf-je-25e-te-lopen-als-een-bejaarde