Functional training is a label for a concept. As with any label it is subject to various interpretations. I originally conceived it as multi lateral training integrating various training modalities (medicine ball, stretch cord, weight training, dumbbells, body weight etc.) to produce significant adaptation in specific performance parameters.
Functional training trains all systems of the body while recognizing and respecting the wisdom of the body. The end result is a highly adaptable athlete who is able to perform without limitations in the competitive environment. Contrast this to biased one- sided training that results in adapted athletes who are inconsistent in performance and prone to injury.