The question you might want to ask yourself is "why am I running with weights?" What practical purpose does it have towards your parkour training? If you plan on doing many runs while carrying weight, than yeah it makes sense... otherwise I like what gear and ninja said... running is already high impact, and no more is needed... running on grass and/or any uneven and unpredictable surface is great for conditioning your entire body... ankles, knees, core, nervous system, I shouldn't need to list any more... just think about it