A recent forum thread I was involved in on StrengthCoach.com prompted me to write about the topic of being able to complete a movement under load, but not at bodyweight.
The actual thread was regarding athletes who could not bodyweight squat, but had good technique under load. The author wanted to know why this was occuring and if it was appropriate to continue to apply load with the goal of; A. improving the movement pattern, and B. increasing strength levels.
I do not believe that it is appropriate to add external load to a pattern when that pattern is "off" under no load. There is an exception to this, which I will talk about, however my general thought is that the consequences to this are more negative rather than positive.
The problem with adding external load to a movement pattern when a person cannot adequately complete the pattern without load is that you are creating artificial stability. It's the reason many people can bench press a significant amount of weight, but have trouble with pushups. The bench is creating the stability that your body must come up with in the pushup. Without that stability, you can't push as hard or as effectively. The same holds true for working out with machines. The equipment provides the stability instead of your body.
"Whats the big deal with that?" you might be asking. Well, if you have any aspirations of getting up from the bench and moving around in real life, or if you are an athlete and need to run around and move during your sport, that "strength" that you have developed without the addition of real stability will be at minimum less useful, and at worst potentially detrimental to your health.
In the example of someone who cannot squat properly unless they are under load, what they are doing is using the force of the weight as a crutch to put them in the proper position. Stability is created by the load, allowing proper mobility to occur at the correct places so that the movement can occur. Unfortunately, this is what is known as "adding strength to dysfunction". When that weight is removed, the stability that was created and is necessary is taken away, and the all important mobility is lost, resulting in an inability to complete the pattern. It's akin to adding horsepower to a car whose alignment is off. That horsepower will result in faster breakdown, as more force is directed inappropriately causing undesired wear and tear.
So basically, "adding strength to dysfunction" means increasing the chance of injury. This is why it is so important to be able to complete fundamental movement patterns before external load is applied, and why programs like P90X and Crossfit are potentially hazardous. These types of workouts throw these rules out the door in the name of "work capacity" or "bravado" and are recipes for disaster.
However, as I mentioned at the beginning of the post, there are some exceptions to the rule. In the SC.com forum thread the idea of the addition of a small amount of load actually being useful to improving the pattern was brought up. In this example, a Kettlebell was used to help the athlete "groove the pattern". While this is still the same concept of adding a load which in turn is causing artificial stability, the difference lies in the amount of load. A small amount of well directed load will create some stability, which will allow the athlete to learn how to squat properly. Again, the amount of load or force is the important concept here. Taking an athlete who cannot bodyweight squat and adding 135lbs to a back squat might result in a decent looking squat under load, but it won't help improve the unloaded movement pattern. Its just too much of a crutch. Performing a Kettlebell Goblet Squat with a 12kilo Kettlebell may in fact be just enough load to teach the neurological system how to move correctly.
You see, for motor learning to occur, there has to be just a little bit of struggle. It has to be just a bit of a challenge to the system, so that your brain can overcome the obstacle and "learn" how to move properly. This is a concept sometimes referred to as RNT, or Reactive Neuromuscular Training. Another common example would be to wrap an elastic band around the knees of someone who goes into valgus collapse during a squat. The band actually pulls the knees further into valgus, but if its just the right amount of force, it tells the brain to "turn on" all the muscles which are responsible to keeping the knees out, and voila! The person can squat correctly!
The key however is not to depend on the crutch forever. The idea should be to remove the band or to get rid of the kettlebell and perform the movement correctly. And that is where the art of coaching lies. Knowing how much load to apply, and when it is appropriate to apply it or take it away is crucial. To much load, no motor learning. To little load, not enough challenge- no motor learning.
As always, the goal of exercise should be to improve movement. Whether that means getting in and out of your favorite recliner with less pain, losing the holiday weight after the new year, or improving your speed and agility on the ice, the same fundamental concepts apply. Everything comes down to the human body, and no matter what skills you put on top of that frame, proper movement is proper movement.