Most people look at training for asthetics and training for function as being exclusive of each other. Most believe that functional training is only for athletes trying to improve aspects of their game. I am about to tell you how this is far from the case.
You invest all of your time and effort into building a body that looks good. Thousands of crunches, pulldowns, and hours of cardio and you have reached your goal.
Scenario 1: You are getting ready to reach a PR in the bench. You get all set up as usual and everything is going well. You unrack the bar and bring it down to your chest. On your way down SNAP!. As your spotter pulls the weight off of you, you know that this means some serious time off, and atrophy of pretty much every muscle that involves the shoulder joint.
What could have happened? One reason could be that your form just slipped and a stabilizer was forced to take on too much of the weight. Another likely answer is synergistic dominance.
Even the slightest variation in a joint with regard to it's orientation can lead to this problem. I could go into the specific details, but I will just give the take home message: Continual use of poor movement patterns leads to the synergist muscles taking on more of the load from the prime mover. Since these muscles are typically smaller, they are not built to handle the same load as say the chest muscles. So as you progress, you don't see this as being bad as long as the weights go up. Eventually, however, you will meet a point where these muscles can't handle the load and an injury will occur. Maybe you will be lucky and only suffer a strain, but why not nip it in the bud all together and forego an injury.
Scenario 2: You are walking down the street with not a care in the world. As you are walking, you step on a crack in the sidewalk and roll your ankle badly.
Scenario 2 pisses me off. It pisses me off because it has happened to me about a hundred times. While you don't need surgery or anything, you can't squat or do cardio for at least a week. This can be especially crushing if you are just coming back and trying to drop all that excess fat you gained by eating like a pig. You are probably saying to yourself, "Surely this isn't caused by some muscular dysfunction, it was an accident." Well, I am here to tell you that it is, and you are about to find out why.
In the first scenario, it is easy to see that the problem can be remedied by making sure that your form on all compound movements is flawless and getting in more exercises that work the stabilizers. This would include more compound movements as well as balance and stabilization work to ensure that these muscles are strong enough in the event your form slips in the middle of a rep.
In the second scenario, the problem is reaction time and the resultant rate of force production. When your foot rolls over the crack, there is a period of latency where you could react and counteract the movement by causing the muscles in the ankle to contract and stabilize the foot. By utilizing exercises that are proprioceptively challenging, you may improve your speed and ability to do this. I remember the first time I stood on a foam roll, within 5 seconds I was flat on my ass. Eventually, I could stand on it very easily and now I can do squats with a decent amount of weight. My progression with the foam roll wasn't even a structured program, I just stood on it whenever I wasn't doing anything at the gym. Oddly enough, in the past 3 months, I have "caught" myself stepping into a situation where my ankle was about to roll, but I responded before it could happen. Now that I am venturing into a structured functional training program I look forward to seeing what that does for my day to day functions.