See HERE. I love the idea (also talked about in a parkour interview I posted months ago) of increasing environmental complexity to test fundamental human movement skills (physical competency).
It's fascinating and fantastic to see this type of training becoming more popular (certainly other types are still valid), and interesting from a point of mechanstic --> systems theory paradigm shift reflected in changing exercise trends, perhaps? (or Perhaps not..).
Anyway, great article and this style of Natural Movement training certainly has something to offer, would mix well with, barbell; kettlebell or martial arts training.