By: Kelly Baggett
The Internal System
To keep it simple, all movement first starts with a neural impulse which is triggered by either a voluntary command or a reflexive one. This command is sent down the spinal cord to the appropriate muscle motor units. These neural impulses have 3 distinct characteristics which will vary in relative importance depending on the type of action needed.
The first characteristic is:
A. How fast can the motor impulse travel from the central nervous system to the muscles and from the muscles back up the spinal cord. This is responsible for quickness, very rapid firing muscular contraction, very rapid bouts of muscular relaxation, and the ability to move rapidly in absence of loading.
Examples of this include:
Foot speed while lieing on your back or standing in place
It should be noted that the ability to relax muscle is very important for rapid movements, especially in cyclical actions. To verify this for yourself simply tap a finger on your desk as fast as you can. Most people will tend to cramp up or lose rhythm due to insufficient and incomplete relaxation in between contractions.
One key characteristic of great sprinters isn't necessarily the magnitude of force they are able to produce in a very short time, or the speed at which their limbs move. Instead, it is their ability to relax completely in between strides that is key. It has been found that muscle relaxation time improves markedly as the athlete's skill improves. In some sprinters, improvement in performance is largely a consequence of strength increase while the ability to relax muscle remains much the same, whereas some talented sprinters improve solely because of an increase in their capacity for efficient muscle relaxation.
The primary role of quickness is to produce high speed movement which does not encounter large external resistance or require great strength, power, or energy consumption.
Quickness may be referred to as the ability of the central nervous system to contract, relax or control muscle function without involvement of any preliminary stretch. It is measured as the time interval or reaction time between voluntary stimulation and the initiation of movement. This time should be distinguished from absolute movement speed, which is the interval from the beginning to the end of movement.
The average movement time of a simple task of unloaded movement of an extremity is .3 seconds, which can decrease by more than 50% in the case of highly trained subjects. Movement time is strongly influenced by motor coordination or precision of movement.
Quickness can involve simple or complex tasks, as well as single versus repeated actions. In boxing or martial arts, quickness would involve thrusting out a fist from rest to execute a punch. Examples of quickness in repeated actions are dribbling in soccer, hitting a rapidly returned shuttle in badminton, or a flurry of offensive blows in boxing. In the latter examples, quickness would refer to the frequency of repeated movements.
The 2nd characteristic of the neural impulse is:
B. How long the motor impulses keep the motor units activated. This is responsible for strength, which requires a muscle be activated for a fairly long time.
The 3rd characteristic of the neural impulse is:
C. The level of the neural impulses being sent. The greater the level of impulse, the more motor units get activated. This is improtant for either great displays of strength, power, or sports type athletic displays. It should be noted that very fast sprinters are distinguisehd by a high level of neural discharge from the central nervous system. If your nervous system was a battery the level would refer to the amount of "juice" the nervous system is putting out.
Now, when you put "A" and "C" together you get motor impulses that are being sent very quickly and at a high level. This is characteristic of athletic displays such as acceleration, jumping, sprinting, etc.
The amount of juice the system puts out is related to nervous system excitability and also tends to be well correlated with emotional excitability, temper, etc., - which is probably why there are lots of potentially good athletes in the prison system! The more juice the more muscle recruitment. During competition the ability of the system to put out this type of energy is a huge advantage but during life it can things complicated.
Someone with an excellent "internal" system might have the following characteristics:
1. Excellent ability of the system to get aroused and send clear and efficient signals to the muscles.
2. Excellent hand speed as shown by the ability to tap a finger against a pad 20+ times in 2 seconds, throw a quality 6 punch combination under a second, type 100+ words per minute, throw a baseball faster than what would be indicated by size and limb lengths, etc.
3. Excellent "unloaded" foot speed as demonstrated by the ability to sprint or tap the feet quickly in place or throw a high speed kick.
4. Quick reflexes.
5. Emotional excitability. Succeptible to outbursts as well as apathy. May have the ability to yell very loud. :)
Now let's see how this relates to the "external" system. Remember the internal system is the nervous system and the external is the muscles, tendons, joints. etc.
The External System
The internal system is the message and the job of the external system is to "display" that message. Without the "display" then nothing happens. Remember, only muscle produces movement. You can have the best battery in the world but without a motor to start you're not going anywhere! In much the same way you can have the best nervous system in the world but you will need a muscular system in order to "display" that nervous system or you're not going anywhere either!
Now, the displays I mentioned above regarding quickness don't require very much muscle at all due to the absence of force, and thus are related nearly entirely to the speed and efficiency with which the nervous system can send messages. Quickness is displayed fully only when the external resistance does not exceed 15% or more of max strength. When you add force to the movement you also add the extent that the external or muscular system is involved. It should be noted that bodyweight adds a substantial amount of force to be overcome. If you weigh 100 lbs and squat 200 lbs then it requires approximately 35% of your max strength just to move your own bodyweight.
For example, cycling your legs when you lie on your back is mostly a display of internal nervous system proficiency, quickness, and absolute speed of movement. When you add force to that same movement by standing on the ground and running, then not only must you cycle your legs, but you must cycle your legs while moving your own bodyweight off the ground. This means that you add force. In this situation the limiting factor becomes how efficiently your external system (musculature) can carry out the signals your nervous system is sending while dealing with that force. If that weren't the case then you would be able to sprint down the track just as easily as you sprint when you lie on your back sprinting against the air. Or you would be able to get down in a pushup position and move your hands just as quickly as you do punching against the wind. The more force you add, the more that external muscular factors become limiting.
So not only must you be able to get your muscle turned on but you have to have some horsepower and strength to turn on when you do. You can have the best internal system in the world, but you need the right external system to display it. In other words, you need strong muscles and all that.
There are many women who fit the characteristics of having a proficient nervous system I described above yet would get smoked in a sprint by most men, because they're muscles are weaker.
This just goes to show you that you don't necessarily have to be so called "quick" or "speedy" in order to be explosive and powerful. It also goes to show you that just because someone may have "quick" feet or "quick" hands doesn't necessarily mean that they will be able to run fast, have great agility, or have a spectacular vertical jump.
The Quickness/Strength Deficiency Evaluation
Now, one way to evaluate how to train someone is to evaluate their relationship between quickness and strength. This is one such observation I make when evaluating an athlete. Sometimes you will need to focus on the efficiency of the nervous system to increase the "level" of the impulse being sent and the display of such. This is typically what plyometric and power training methods do. The focus on these methods is on putting out a whole lot of neural energy in a very short period of time.
Sometimes you will need to increase the body's ability to better "express" the messages from the nervous system. This is what strength or hypertrophy training does. Usually it's not too difficult to identify the deficiency in an athlete and train accordingly. I promise to get more specific with the specifics of it in the future but let's run through a couple of scenarios:
Needs: Focus on increasing explosive muscle recruitment (increase level of internal neural impulse) - Power training, plyometrics etc.
Needs: More raw material in which to express his already good internal and external systems. - Hypertrophy training. More muscle = more raw material.
Needs: Everything. - A general all around program with a focus on low level movement efficiency and general strength.
Needs: Strength and hypertrophy followed by Power - This type of athlete represents the type that can progress overnight and suprise people with startling improvement. Once his strength levels are boosted up, then power work can be used to intensify his ability to quickly recruit motor units, the results often being spectacular. Often this type of athlete will have to work extra hard to maintain muscle size and strength.
quickness: Decent but not outstanding
Strength: Decent but not outstanding
Needs: This athlete would require further evaluation on the relationship between his power and his max strength. A depth jump test could be used to assess his reactive ability. If he's more explosive from a standstill then power training would predominate. If he jumps a lot higher from a runup or depth jump then strength training followed by power work. If nothing else the progression might go like this:
Block 1- high volume low intensity movement efficiency work + basic strength
Block 2- high volume strength work + low volume movement efficiency
Block 3- high volume power work (jumps squats/acceleration runs) + low volume drop jumps
Block 4- high volume intense plyometric work (depth jumps)
Each block would run 4-7 weeks in duration with a frequency an average of 2-3 times per week for both upper and lower body.
As you can see there it's not too difficult. Most people will have an observable deficiency somewhere. The athletes who are already quick and strong will already be good athletes.
Siff, M. "Supertraining." 2003