It can be very simple, but yet so complicated. I'll try to make it very short and rather simple...
Let's start off with an example. The knee. Kiteboarders think it's very important to have strong knees, and I get asked about this a lot.
It is correct, that the best way to prevent injuries in the knees is functional training. But it's easy just to say that, because peoples perception of "functional training" is in my honest opinion crap.
I've been teaching this subject for many years and I see it so often. Even when I educate physiotherapists or personal trainers. If I ask someone to show me a functional exercise, they will (7 out of 10 times) show me a bench press or dumbbell chest press etc. Are they functional? No, not if you ask me. Functional training is training with a specific purpose/goal, which stimulates the nervous system as much as possible and involves long muscle chains in a movement which mimics a movement from your daily life/sport. When do you ever do the movement of a bench press in your daily life? Never...
The above also (in-direct) tells you that functional training and has a great element of core training. You can't do functional training without involving the core. And the greater the core involvment is, the more you gain from it in agility and power.
Back to the knee example; a goal with functional training can be "just" to strengthen the knee. Many people will then do one legged leg press or squats. But that's (almost) just a waste of time. When do you ever do the movement of a standard squat? You never take a lot of weight on your shoulders behind your neck and then go up and down. Sure it's an relative good exercise for core strength and you are using long muscle chains, but where is the functionality? No where. You can't relate the movement to any natural movement. But it's easy to convert it. Hold the bar in the front and do a front squat. Now the forces are similar to a heavy lift, because the weight will try to pull you forward. That makes it functional. But still not a very good exercise to prevent injuries in the knees.
Lets look a little closer at the one legged leg press. Does it strengthen the knee? Yeahhhh, I supose it does, But does it minimize the risk of injury? No, not at all! No matter how strong your knee is, there are several other and more important factors in lowering the risk of getting injured from kiteboarding. The balance between the agonist and antagonist. Do you remember to do exercises for biceps femoris? (back thigh) And forget all about a leg curl. A hard impact from a hot landing in kiteboarding has a huge negative influence on the knee. If the muscles are not pulling at the same strength on each side, the risk of injury is higher. And more important; does the nervous system activate the muscles at exactly the same time? Probably not, if you're just doing leg press and leg curls. Or squats for that matter.
Balance, stability and coordination! These are the key words! Get those things in to the exercise and you'll have functional training. Strength is in my honest opinion secondary, but if we think a little about exercise physiology, then we know that the biggest stimulation of the nervous system is under heavy load. And there for is strength also important, but it's a bi-product of the other things.
I have made a small knee training program for kiteboarders fresh out of rehab (rehab is often a lot of leg curls, light squats or leg press, which is stupid, but I've seen it a million times). That's video number 2. That is a really good place to start, if you want a strong and stable knee to prevent injuries.
Level 1 (fresh out of rehab)
Level 2 has 2 levels and it's a small program for "normal people", who want to prevent injuries. It's also great for people, who has recovered from and injury.
After level 2, you can do the same exercises and then add weights and maybe incorporate more balance and coordination. Like using a BOSU:
A great exercise (for well trained kiteboarders) is this:
It has all the elements from kiteboarding. We exercise in the right direction. Lateral, sideways. We're always standing sideways to the movement, when we're kiteboarding. This exercise contains it all, right direction, balance, coordination, core, stability and power. THAT's functional training and THIS will prevent knee injuries.
Why is bench press not functional?
I want to point out why bench press isn't functional. Because this is what we always have been taught.First of all, it's not a natural movements, as I said earlier. That's a good point. But many fitness professionals will say that there is a great activation of the rotator cuff muscles and that is healthy for the shoulder and increases stability. But is that true? Imagine laying on a bench, like the picture, and you have to push the barbell up. How does that effect the shoulder? It will be forced backwards (down in the bench) at the same time as the rotator cuff will try to stabilize the shoulder and keep the balance. That sounds functional, but at least half of all people (based on my own observation) make a big mistake. The shoulder blade gets pushed back, but what should stop that movement? Often it is the bench, and that is very unfortunate. That put Serratus Anterior out of the game and teaches your shoulder to turn off serratus under heavy load. And the function of the serratus is to keep the lower part of scapula (shoulder blade) close to ribs and prevent a protruding scapula (winging) (read more about that subject here, click). So when you're out on the water and makes a bad blind landing, the shoulder will be in a outer position under stress. And then the serratus wont function properly, which makes the shoulder rotate forward and down, when at the same time the shoulder blades will be protruding. Does that sound healthy? No, absolutely not! That can cost you a ligament very fast. If serratus had functioned properly, it would have fixated the shoulder blade (the base of the whole shoulder) and kept the shoulder in an optimal position (where it is strongest and most stable). That will probably prevent the injury from happening.
So how should you do functional training for the chest? Like this:
This one can be used for rookies to become strong and stable enough to do the exercises above:
People with poor serratus anterior activity will look like a gorilla. You've probably seen them around the gym. On top of that they have shortened the pectoralis major and minor, because they have been doing too may chest exercises (wrong) and not enough for the upper back.