Post by John A. Casler on Jun 15, 2008 7:34:25 GMT -8
I was going to write a bit on CAT, but Jaime posted this to Super Training and Mel was always quite good at explaining things.
CAT IS PART OF LIFE
By Mel Siff
What is not often appreciated is the fact that it is difficult NOT to
use Compensatory Acceleration (CA) in any movement, since the
neuromotor control systems of the body generally try to promote
efficiency, the ability to execute a movement and safety by altering
posture, muscle tension, joint angles, velocities and acceleration to
suit every situation. Without certain phases of CA taking place
throughout every movement, actions would not be completed or would be
executed ineffectively.
If some force is not exerted throughout a movement, then it means
that the athlete is relying entirely on momentum to complete the
action, which is every rare, especially in non-explosive movements.
And if no attempt is not made to compensate for decreases in
momentum, the load is will stop moving and be pulled down back
towards where it came from. So, the nervous computer in the body
ensures that the muscles increase their tension to keep the load
moving in the appropriate direction.
In going through this analysis, one then can appreciate certain
limitations of CAT:
1. CA is limited by how much strength one has, since maximal
acceleration is determined by your maximal strength. Thus, one
cannot accelerate a load indefinitely. One's ability to use CAT is
limited by one's strength in a given movement and part of this has to
do with technical skill.
2. CAT is inadvisable if acceleration is in the direction of gravity. It is unwise and potentially dangerous to try to speed up
the downward or eccentric direction of any exercise, because this
means that you will have to generate even greater 'amortising' force
to stop the movement at the bottom of the lift. For example, it is
not a good idea to try to speed up the downward phase of a squat or
bench press (guess why?). There are a few exceptions in Olympic
lifting, but they are not relevant to the average weights user.
3. The continued application of CA during a movement is illogical and
impossible, since unmitigated acceleration would mean that the
movement would never end or slow down. One is always working over a
given range of joint movement and this, in addition to the
limitations of your strength (and endurance, sometimes), compels you
to slow down the movement. Just like any elevator, there is a phase
of acceleration in any movement, a period of constant or undulating
velocity, and a final phase of deceleration (negative acceleration).
4. CA may not or should not take place to speed up the action of a
single joint in a given phase of a movement, particularly in a
complex movement where several joints are involved in the lifting
action (e.g. a push press, power clean, snatch, deadlift and cable
crossovers). One needs to recall the well-known rule that the
body 'knows only of movement, not muscles'. Thus, one may attempt to
alter the integrated output of the body, i.e. the movement of the
BAR, but not of any SINGLE joint movements or muscle actions which
take part in producing that movement, unless one is willing to cope
with the greater stresses and altered motor patterns which result,
and for a very good reason.
THE CAT PRINCIPLE
This analysis now enables us to appreciate what Dr Hatfield is
referring to when he advises the use of CAT. What he means is that
you can increase muscle tension and therefore, its ability to enhance
strength and hypertrophy, if you make a deliberate attempt to produce
maximal acceleration of the load throughout the range of movement.
He is stressing this point because some folk exert just the bare
minimum of acceleration to allow the movement to be completed at even
very slow speed. He is saying that the bare minimum may simply give
you the bare minimum of results and, that if you try to work as hard
as possible to speed the movement up, the better your progress will
be, provided that you do not overtrain or produce serious technical
errors.
Of course, he is aware of the well-known hyperbolic relationship
between force and velocity, which means that the greatest force in
non-ballistic movement is produced at very low velocity. The
relevance of this curve to CAT is that one just cannot accelerate
near maximal loads at the same rate as much lighter loads, but it
does not prevent you from trying to accelerate the load as much as
you can, even if the acceleration is very small.
By the way, it is important to realise that the standard hyperbolic F-
V curve does not apply to explosive movements such as plyometrics or
any other rebound actions (See Siff & Verkhoshansky 'Supertraining'
1998 Ch 3.3) and that the involvement of CA during such movements is
much more complex.
CAT CONTAINS OTHER COMPENSATIONS
Some coaches believe that they may have discovered a unique way of
training (which we may biomechanically call 'Mechanical Realignment')
which involves changing posture, joint position, leverages and so
forth during a given exercise, but, as mentioned earlier, this is
just another naturally occurring phenomenon which takes place to
enhance the efficiency, safety and ability to complete a given
movement.
Video and EMG analysis has shown that there are frequent and regular
changes in joint disposition and muscle activation to enable a
movement to be carried out in the most appropriate way for a given
individual at a given time. As with the usual CAT method, it is
difficult NOT to change one's posture, joint positions or muscular
efforts, particularly when the load is increased or fatigue sets in
(just think of how the butt tries to rise when one is doing prone leg
curls or how the hips try to lift off the bench during a heavy bench
press).
Yes, sometimes the movement may be inefficient or unaesthetic, but it
may enable an injured person to execute a movement which might not be
possible if the recommended technique were to be attempted. This may
also happen in the case of novices who have not yet acquired the most
effective motor skills. They deliberately compensate by using the
muscles and joints which will enable them to complete the movement,
right or wrong!
DIFFERENCE BETWEEN ACTION AND TRAINING METHODS
So, alteration of posture and other mechanical features of an
exercise is just another way of producing CA, which, in turn is just
one aspect of the body's natural compensatory mechanisms which
involve the use of feedback from the musculoskeletal system back to
the nervous control command centres.
Even 'plyometric' action may be thought of as another one of these
compensatory mechanisms, since the use of ballistic stretch increases
the overall efficiency of movement. However, plyometric action,
which takes place quite naturally in many daily activities like
running is not the same as plyometric training, which involves using
combinations of plyometric actions in the form of an organised set of
drills. Similarly, one may distinguish between compensatory
acceleration and mechanical realignment actions and compensatory
acceleration and mechanical realignment training.
CAT AND FATIGUE
Contrary to what is sometimes believed, all forms of compensation,
realignment or change in the shape of 'strength curves' are not simply a result of fatigue, but also involve neural interventions to maintain motor efficiency, to spread activity out among large groups of muscle fibres, response to pain/discomfort or perception of either, and level of psychological arousal. Consequently, it is inappropriate to implicate the action of fatigue too freely in trying to understand the nature of strength and hypertrophy training. Certainly, it plays a significant role in many processes of adaptation, but there are several other players in the theatre of the body.
FORCE CHANGES MOST OF THE TIME
Though John Hannon wrote that "When you first start the bar up you
have a greater force applied, to start the bar into motion, then the force is constant over the remainder of the lift", force plate analysis has shown that force changes throughout every movement, along with acceleration and velocity (examples of this are given in Vorobyev 'Textbook on Weightlifting' 1978; Enoka R The pull in Olympic Weightlifting' Med & Science in Sports' 11(2), 1979: 131-137; Garhammer J Cinematographic & Mechanical Analysis of the Snatch lift 'International Olympic Lifter' 2(6), 1975 : 5-15)
In certain cases, the acceleration even reverses, e.g. during the
primary stage of the 'double knee-bend' action of the Olympic snatch and clean, and then suddenly increases in the opposite direction so that the force exerted on the bar approaches twice the weight of the load. In such cases the angles of the joints involved may increase or decrease and vice versa during the lift, so that the most powerful parts of the body may be used in the best possible way to execute those complex movements (see above references).
CAT IS PART OF LIFE
By Mel Siff
What is not often appreciated is the fact that it is difficult NOT to
use Compensatory Acceleration (CA) in any movement, since the
neuromotor control systems of the body generally try to promote
efficiency, the ability to execute a movement and safety by altering
posture, muscle tension, joint angles, velocities and acceleration to
suit every situation. Without certain phases of CA taking place
throughout every movement, actions would not be completed or would be
executed ineffectively.
If some force is not exerted throughout a movement, then it means
that the athlete is relying entirely on momentum to complete the
action, which is every rare, especially in non-explosive movements.
And if no attempt is not made to compensate for decreases in
momentum, the load is will stop moving and be pulled down back
towards where it came from. So, the nervous computer in the body
ensures that the muscles increase their tension to keep the load
moving in the appropriate direction.
In going through this analysis, one then can appreciate certain
limitations of CAT:
1. CA is limited by how much strength one has, since maximal
acceleration is determined by your maximal strength. Thus, one
cannot accelerate a load indefinitely. One's ability to use CAT is
limited by one's strength in a given movement and part of this has to
do with technical skill.
2. CAT is inadvisable if acceleration is in the direction of gravity. It is unwise and potentially dangerous to try to speed up
the downward or eccentric direction of any exercise, because this
means that you will have to generate even greater 'amortising' force
to stop the movement at the bottom of the lift. For example, it is
not a good idea to try to speed up the downward phase of a squat or
bench press (guess why?). There are a few exceptions in Olympic
lifting, but they are not relevant to the average weights user.
3. The continued application of CA during a movement is illogical and
impossible, since unmitigated acceleration would mean that the
movement would never end or slow down. One is always working over a
given range of joint movement and this, in addition to the
limitations of your strength (and endurance, sometimes), compels you
to slow down the movement. Just like any elevator, there is a phase
of acceleration in any movement, a period of constant or undulating
velocity, and a final phase of deceleration (negative acceleration).
4. CA may not or should not take place to speed up the action of a
single joint in a given phase of a movement, particularly in a
complex movement where several joints are involved in the lifting
action (e.g. a push press, power clean, snatch, deadlift and cable
crossovers). One needs to recall the well-known rule that the
body 'knows only of movement, not muscles'. Thus, one may attempt to
alter the integrated output of the body, i.e. the movement of the
BAR, but not of any SINGLE joint movements or muscle actions which
take part in producing that movement, unless one is willing to cope
with the greater stresses and altered motor patterns which result,
and for a very good reason.
THE CAT PRINCIPLE
This analysis now enables us to appreciate what Dr Hatfield is
referring to when he advises the use of CAT. What he means is that
you can increase muscle tension and therefore, its ability to enhance
strength and hypertrophy, if you make a deliberate attempt to produce
maximal acceleration of the load throughout the range of movement.
He is stressing this point because some folk exert just the bare
minimum of acceleration to allow the movement to be completed at even
very slow speed. He is saying that the bare minimum may simply give
you the bare minimum of results and, that if you try to work as hard
as possible to speed the movement up, the better your progress will
be, provided that you do not overtrain or produce serious technical
errors.
Of course, he is aware of the well-known hyperbolic relationship
between force and velocity, which means that the greatest force in
non-ballistic movement is produced at very low velocity. The
relevance of this curve to CAT is that one just cannot accelerate
near maximal loads at the same rate as much lighter loads, but it
does not prevent you from trying to accelerate the load as much as
you can, even if the acceleration is very small.
By the way, it is important to realise that the standard hyperbolic F-
V curve does not apply to explosive movements such as plyometrics or
any other rebound actions (See Siff & Verkhoshansky 'Supertraining'
1998 Ch 3.3) and that the involvement of CA during such movements is
much more complex.
CAT CONTAINS OTHER COMPENSATIONS
Some coaches believe that they may have discovered a unique way of
training (which we may biomechanically call 'Mechanical Realignment')
which involves changing posture, joint position, leverages and so
forth during a given exercise, but, as mentioned earlier, this is
just another naturally occurring phenomenon which takes place to
enhance the efficiency, safety and ability to complete a given
movement.
Video and EMG analysis has shown that there are frequent and regular
changes in joint disposition and muscle activation to enable a
movement to be carried out in the most appropriate way for a given
individual at a given time. As with the usual CAT method, it is
difficult NOT to change one's posture, joint positions or muscular
efforts, particularly when the load is increased or fatigue sets in
(just think of how the butt tries to rise when one is doing prone leg
curls or how the hips try to lift off the bench during a heavy bench
press).
Yes, sometimes the movement may be inefficient or unaesthetic, but it
may enable an injured person to execute a movement which might not be
possible if the recommended technique were to be attempted. This may
also happen in the case of novices who have not yet acquired the most
effective motor skills. They deliberately compensate by using the
muscles and joints which will enable them to complete the movement,
right or wrong!
DIFFERENCE BETWEEN ACTION AND TRAINING METHODS
So, alteration of posture and other mechanical features of an
exercise is just another way of producing CA, which, in turn is just
one aspect of the body's natural compensatory mechanisms which
involve the use of feedback from the musculoskeletal system back to
the nervous control command centres.
Even 'plyometric' action may be thought of as another one of these
compensatory mechanisms, since the use of ballistic stretch increases
the overall efficiency of movement. However, plyometric action,
which takes place quite naturally in many daily activities like
running is not the same as plyometric training, which involves using
combinations of plyometric actions in the form of an organised set of
drills. Similarly, one may distinguish between compensatory
acceleration and mechanical realignment actions and compensatory
acceleration and mechanical realignment training.
CAT AND FATIGUE
Contrary to what is sometimes believed, all forms of compensation,
realignment or change in the shape of 'strength curves' are not simply a result of fatigue, but also involve neural interventions to maintain motor efficiency, to spread activity out among large groups of muscle fibres, response to pain/discomfort or perception of either, and level of psychological arousal. Consequently, it is inappropriate to implicate the action of fatigue too freely in trying to understand the nature of strength and hypertrophy training. Certainly, it plays a significant role in many processes of adaptation, but there are several other players in the theatre of the body.
FORCE CHANGES MOST OF THE TIME
Though John Hannon wrote that "When you first start the bar up you
have a greater force applied, to start the bar into motion, then the force is constant over the remainder of the lift", force plate analysis has shown that force changes throughout every movement, along with acceleration and velocity (examples of this are given in Vorobyev 'Textbook on Weightlifting' 1978; Enoka R The pull in Olympic Weightlifting' Med & Science in Sports' 11(2), 1979: 131-137; Garhammer J Cinematographic & Mechanical Analysis of the Snatch lift 'International Olympic Lifter' 2(6), 1975 : 5-15)
In certain cases, the acceleration even reverses, e.g. during the
primary stage of the 'double knee-bend' action of the Olympic snatch and clean, and then suddenly increases in the opposite direction so that the force exerted on the bar approaches twice the weight of the load. In such cases the angles of the joints involved may increase or decrease and vice versa during the lift, so that the most powerful parts of the body may be used in the best possible way to execute those complex movements (see above references).
