Have you noticed that a lot of the home workout products require you to move ballistically? I’ve personally observed many fellow personal trainers asking their clients to exercise in this manner as well. Why is that? After all, I thought ballistics was the science that studied the behavior of projectiles. Why ask human beings to mimic projectiles in their exercise programs? I’m going to be pollyanna for a moment and assume the best rationale.
Trainers, and indeed many athletes, are educated to believe that you need to move fast if you are going to be fast. They learn that power, or the ability to produce mechanical work over a span of time, is developed by recruiting your nervous system in a certain way and that this requires ballistic movement. I was educated to believe this as well and there is a fair amount of research supporting this conclusion. But let’s deconstruct this further.
The basic formula for power is Power = work/time where work = Force * distance. So the original formula could be written Power = force * distance/time. Let’s say you kept the distance you need to move the same, say 1 ft., and the time in which you move that distance likewise the same, say 5 seconds. What would happen if you just focused on increasing the amount of force you generate?
Remember that Force = mass * acceleration. So you can increase the amount of force generated by either moving a greater mass or moving the same mass with greater acceleration or both. So what would happen if you focus on developing the ability to generate more force, not through greater acceleration but by developing the strength with which to move greater amounts of mass? You guessed it, you would develop the ability to generate greater power. It’s straightforward when seen as the equation: power = mass * acceleration * distance/time. So if you keep acceleration, distance and time constant and just develop the ability to move more mass (i.e., weight in the exercise context) the power must increase. No amount of exercise related scientific research could bypass this. It’s basic physics.
So what many personal trainers have done is focus on developing a client’s capacity to accelerate, to move a given weight in less time, or to move a greater distance in the same time while they simultaneously develop a client’s ability to move greater amounts of mass. They have focused on increasing their client’s power by developing every variable of the power equation. Can you develop greater power by this approach? Obviously yes. But at what cost to the client in terms of risk of injury?
Personal trainers need to address that question because they are in the business of improving a client’s physical capabilities and nothing retards progress towards that goal more then injury and having to take time away from exercise. Personal trainers are not working with indestructible robots. They work with human beings and they are subject to the same oath that doctors take: first do no harm. So just because personal trainers can develop power in their clients by having them move ballistically, doesn’t mean they should.
If someone comes to me at Inner Strength Fitness Consulting with the desire to become more powerful in their chosen sport, I prefer to focus on developing their strength, their ability to move mass. I do this in the safest manner I know how:
1. I have them take a couple of seconds to start moving the weight.
2. I have them lift the weight the rest of the way in five to eight seconds.
3. I have them take a couple of seconds to change direction.
4. I have them lower the weight in five to eight seconds.
In other words I have my power-motivated clients focus on moving the resistance in an exceedingly slow and controlled manner. Perhaps my clients could move a little faster and it would still be safe. At some rate of speed, slow is safe enough. But it doesn’t hurt to have that added measure of insurance against injury that moving very slowly provides.
In my judgement, erring on the side of less risk of injury is entirely consistent with a high standard of care. So you can train ballistically if you want to and if you are a trainer, you are legally allowed to train your clients in this way. But unless you want to suffer the fate of most projectiles, what good is training like one?