When we talk about exercise, we reference movement as occurring in 3 planes of motion. Sagittal (front-to-back), frontal (side-to-side) and transverse (rotational) Life occurs in these 3 planes of motion yet a lot of times people go workout in the gym (or workout at home) in only the sagittal plane. Examples would be doing some biceps curls, triceps extensions, forward lunges, running a bit on the treadmill and doing some crunches and then calling it a day. Doing this may get you really really good at going forward and back but you are missing out on the other 66% of how you move in a day.
For those of you who are not well versed in the manners of movement screening/functional movement screening, I aim to shed a little more light on the subject and hope to simplify the reasoning behind why these screens are important, both to the client and the trainer.