Disclaimer: Geeky stuff ahead. If you're afraid of physics, do not read. Also, I don't have everything in order just yet, but I wanted to release this before going to Poland, so the missing Figures will be inserted ASAP. Now Anna, a good friend and student of mine, decided to work on her high kicks. Determined, she told me she was going to stretch a lot. That's the point where, as a trainer, I felt the need to intervene and set things into persepective. You see, while some people might definitely benefit from some targeted flexibility training, what most need is actually mobility. Where's the difference? Well, in a nutshell, flexibility measures the "length" (or rather, the ability to relax) of your muscles, whereas mobility measures the range of motion (ROM) you can take a joint through under control. For my german speaking readers, this is pretty much the difference between "aktive Beweglichkeit" and "passive Beweglichkeit" [WEI2010]...