Pattern overload is an unofficial term that
defines an injury to soft tissues (muscles, tendons & ligaments) resulting
from repetitive motion in an isolated pattern of movement, or a restricted
movement in one or more planes of motion.
Pattern overload and/or repetitive stress
injuries result primarily from:
1. An inability to properly load share
(using the right muscles, but at the wrong time)
The human body is remarkably efficient in a
sense that it will recruit as many muscles as it can across as many joints as
possible to naturally provide optimal load sharing. The body will always
attempt to take the path of least resistance for any task you ask of it.
A common example of improper load can be seen
by one who attempts to perform a rowing type of movement with the shoulders pre-retracted
(pulled back, prior to initiating the pull). This ineffective technique
disrupts the natural load sharing recruitment sequence and leaves the muscles
in the shoulders and arms to take on more work than would otherwise be
necessary. Performing rows in this manner will lead to strain and trigger point
development in both teres muscles, as well as parts of the rotator cuff, and will
ultimately result in shortened/tightened retractor muscles of the back, and
non-functional shoulder girdle movement patterns will develop. When this
happens, the shoulders blades are inhibited from moving freely due to the lack
of mobility, which will negatively affect performance of any movement while
increasing the chance of injuries.
A loss of mobility in the scapula (shoulder
blades) due to short/tight retractors can lead to anterior subluxation (partial
dislocation in the front part of the shoulder) in the shoulder joint, and a
popping sound will start to manifest (commonly while doing the same movements
that lead to pattern overload of the shoulder in the first place).
Depending on the severity of the damage,
restoring natural and optimal function may never regenerate 100%. If permanent
damage is done, creating a structurally balanced shoulder girdle by developing
the lower traps and external rotators is your best bet at making the joint as
functional and pain/injury free as possible. Pattern overload can happen in any
joint throughout the body, the shoulder was simply used as an example in this
case because of how common it is due to the versatility of the joint.
2. Being restricted to a specific motion
with loss of natural movement in one or more planes (as is the case when using
a machine, and to a lesser extent a barbell because it is a fixed piece of
equipment)
Repetitive stress injuries are due to
repetitive exposure to a particular movement, and can happen to anyone who regularly
performs the same movements, in the same manner, with the same amount of
effort/difficulty, on a daily basis. Common examples of this are athletes,
musicians, office workers, assembly line workers, and even, people that
primarily workout on machines or just do the same workouts for years on end.
To prevent faulty recruitment patterns from
developing, a smart trainee will focus on creating a structurally balanced
physique, with the use of free weights that enable the body to move and recruit
naturally, and devote time to training muscles that are not worked in the
lifters everyday life or sport. For example, if you take an athlete who’s sport
calls for lots of lunging and running type movements, and then focus on more
lunging type movements (which is the same thing they do all day, every day, as
is) in the gym, the chance of them developing an injury to any of the muscles
used in the lunge, or their sport, are more likely to get injured because of
the repetitive stress (machines, and some barbell movements are included as
they can promote repetitive stress injuries by restricting you from moving
freely).
3. Over-use of any given pattern of
movement, regardless of freedom of joint motion (doing the same movements again
and again irrespective of whether or not you are using machines or free weights)
The body has a finite amount of neurological
energy with which to drive its population of roughly 250 million muscle fibers.
The nervous system is not only capable of recruiting a specific muscle to
perform a task, but to also selectively recruit specific motor units within a
given muscle. As stated above, the body will naturally attempt to conserve as
much energy as possible by choosing the path of least resistance, while attempting
to keep the desired movement you intend to do as smooth as possible (which
further conserves energy).
Neuromuscular isolation (muscle control, or the
ability to activate and isolate, as demonstrated when a bodybuilder makes a
muscle pop for example) is what is needed to produce optimal intramuscular
tension. If you want to build the most muscle and/or strength possible it’s
necessary to recruit and fatigue as many motor units as possible. The greater
intramuscular tension that can be produced, the faster progress will be
regardless of the goal.
Neurological efficiency (the ability to recruit
as many motor units as possible) is a developed trait which takes place over a
sustained period of time. A beginner, or someone with little training
experience may only be capable of recruiting up to 60% of their available motor
units, where as a lifter with significantly more proper training experience may
be able to recruit up to, and over, 85% of available motor units.
Exercises that are performed seated or lying
down are generally the least neurologically demanding, although they offer an
increased level of recruitment to the muscle being targeted. Obviously greater
levels of recruitment allow for more weight to be used, meaning more strength
and/or muscle can be developed. Exercises that are performed standing, or are
of a high coordination nature like Olympic lifts, or plyometrics, are the most
neurologically demanding and will fatigue the nervous system faster. Machines,
and some barbell movements, don’t allow the nervous system the freedom it needs
to protect the working joints and muscles from injury by trapping the body into
an unnatural fixed position.
If you were to carefully analyze the execution
of any free weight lift, you would fail to see the exact same rep performed twice
in a row, regardless of how well the person performing the exercise has
mastered it. The path in which the weight travels will change with each rep as
the nervous system attempts to take the path of least resistance by
distributing the load differently as the muscles fatigue, and it does so by varying
the path of resistance (bar/dumbell path) which is just another mechanism for
conserving energy and preventing unwanted overload in specific areas.
When using a machine, or in some cases a barbell,
the path is restricted and unchanging unless you contort yourself while under
tension, and this is what can lead to the development of faulty recruitment
patterns, and possibly do irreversible damage to the capsular structures surrounding
the relative joints (as well as set you up for long term injuries). When using
machines or barbells, the population of muscle fibers experiencing maximum load
is isolated (which may be the goal, as it generally is for those solely looking
to build muscle). The motor units and muscle fibers most suited to move the
working weight in the given pattern and movement plane dictated by the machine
will experience fatigue much sooner than when performing the same exercise
without such restriction. As the muscle fibers specific to the movement pattern,
dictated by a machine/barbell fatigue, one is left with progressively less
dynamic control over the load and working joints, and this can result in insult,
and possible damage, to the working connective tissue, tendons, and muscle
fibers.
As support for the relative joints fail, it's
common to see one of two things happen. One will either squirm around on the
machine attempting to find new fiber populations to move the load (which is a
dangerous means of changing fiber populations), or they attempt to rely on the
stretch reflex of working connective tissues to complete the final reps of the
set by bouncing out of the bottom position of a lift (examples being bouncing the
bar off the chest during barbell presses, bouncing the thighs off the torso
during a leg press, springing the shoulders at end range of motion on the pec
deck, or bouncing out of the bottom position of a full range of motion squat).
This leads to damage to the ligaments and capsular structures of joints, not to
mention the potential derangement of the joint itself.
This is pretty serious when you consider the fact
that connective tissue heals considerably slower than muscle tissue, and that motor
control may be compromised secondary to damaged mechanoreceptors in relevant
capsular and ligamentous tissues. Muscle injuries heal quickly whereas tendons
and ligaments will have little regeneration at best. A muscle injury, like a
sprain, can almost fully recover in just 7 days, whereas a soft tissue injury
will take up to, and sometimes even longer than, 12 months, and that's just
referring to it healing to the best of its ability, not getting back to where
it was prior to the injury.
Surrounding each joint is a capsule that aids
in joint stability at end ranges of motion, serves to lubricate the joint
surfaces, and is loaded with proprioceptive neurons called mechanoreceptors
that are constantly communicating with your brain and monitoring your every
move.
When an individual trains on machines and/or
overuses any form of guided resistance, the fatigue and loss of motor control
in the relevant movement pattern and plane of movement often leads to overload
of the joint structures. These structures, predominantly consisting of
collagen, do not stretch well, or bounce back well from repeated stretch. The
best analogy is that of a 6-pack of pop – after removing a can from the
connective plastic, it is impossible to jam the can back in where it came from.
This is pretty much how joint capsules react from ineffective load sharing, repeatedly
performing the same movement patterns, or just using poor form when lifting
weights regardless of the implement employed (free weights or machines).
A joint with stretched capsular structures
begins to lose its optimal working relationships and eventually tries to fall
out in positions specific to the dysfunction. This is especially common in the
shoulder joint due to its versatility. With decreased support from capsular
structures, there must be a directly proportionate increase of dynamic support
by the surrounding muscles.
Should a joint complex be even mildly
traumatized, the stabilizing muscles, such as the rotator cuff in the case of
the shoulder for example, will be taxed with the burden of trying to maintain
an optimal axis of rotation in the now dysfunctional joint. Should the muscles
become fatigued from repetitive work and overuse, combined with the now added
burden of trying to maintain optimal working relationships in the joint, an
eccentric rotation (partial dislocation) of the most mobile segment in the
joint is likely.
As an eccentric motion (partial dislocation) is
produced secondary to failure of the respective stabilizing muscles, the
joint's ligamentous and capsular structures are progressively challenged.
Without restoration of dynamic stability, joint derangement is likely to occur.
A partial dislocation of the joint results in
what is called a subluxation. The joint complex demonstrating some level of
instability, as a result of pattern overload, will begin to make popping
sounds. If the condition progresses, pain is associated with the unusual joint
sounds and the person suffering from it can usually tell a therapist precisely
what movement causes it, often the movement that causes popping sounds or pain,
mimics the exercise which induced the injury.
As the capsule and ligaments related to a
specific joint become more and more imbalanced (ex. tighter in some areas in
relation to others), there's progressive dysfunction in the proprioceptive
messages being sent to the central nervous system with regard to where the
joint is in space. This produces what is called a proprioceptive deficit, which
basically means that the brain thinks, because it is being told so by the mechanoreceptors
in the joint, that the joint is somewhere that it actually isn't. It is
deceived, for the lack of a better term.
A person with a proprioceptive deficit may
develop a pattern for the work of varying muscle recruitment order in an
attempt to effect changes in joint position, leading to pathological motions.
When this happens you’ll notice a loss of performance during activities that
require fine motor control, like a golf swing. For example, if you’re a golfer,
and happen to develop pattern overload in the shoulder, which happens from
performing behind the neck pulldowns when your available range of motion
doesn’t allow for that movement to be performed, or using the pec deck with
extreme ranges of motion, you may increasingly experience swing errors.
Due to poor form, regardless of the chosen
implement (machine, barbell, etc), many people repetitively insult their
working joints and muscles while working out. As you may know, pulling the bar
behind the head places the arm in full horizontal abduction and full external
rotation which places maximum stress and strain on the anterior joint capsule
of the shoulder, especially if there is a lack of available range of motion or
flexibility in the shoulder due to tight/short pecs and/or lats. As the
capsular and ligamentous structures become progressively more lax, the brain
begins to receive faulty information from the articular (structural component
of a joint) proprioceptors. This leads to a loss of motor control and an
increase in pain and inflammation, both of which may lead to permanent loss of
performance.
This results in an imbalance in the capsular
and ligamentous structures of the shoulder that will not only send faulty
information to the brain, but the body will attempt to make things easier by
activating key muscles around the shoulder and possibly beyond. When a joint is
functioning normally, the motor command leaving the brain expresses itself
quite accurately in the body.
When there is a proprioceptive deficit in one
or more joints, the motor command leaving the brain contains the necessary
information to produce the desired movement, yet the movement itself actually
looks completely different. This is often a source of frustration for athletes
that have noticed a loss of performance in their sport after experiencing one
or more injuries to joints. They basically ask their body to do something but
physically can’t do it, and what they’re trying to do looks completely
different than what they are doing.
When performing movements such as various types
of rows and shoulder abductions, the movement will be initiated from the upper
trapezius with a shoulder-hiking action. In the case of shoulder abduction
(lateral raise), there is often increased effort from the upper traps in the
beginning of the movement to carry the arm through mid and upper ranges of
abduction and there may be an associated pain with this movement.
Pattern overload isn’t always a local issue
specific to the joint where pain is felt. It is common for people with pattern
overload to complain of abnormal nagging pains in an unknown origin. This is
likely to result from faulty motor recruitment of muscles at distant locations
taking on unnecessary stress during normal activities. As it relates to the
shoulder, it’s generally the lower traps and retractors that fail to activate
to provide the shoulder with the stability needed to avoid anterior subluxation.
In some studies researchers placed traction and electrically stimulated
mechanoreceptors at the C3-4 level and were able to record significant EMG
(electrical activity) responses in muscles such as the traps, triceps, abs and
hamstrings.
These findings suggest that the messages sent
to the brain, as produced by varying intensities and lines of pull on the joint
capsule, may make the brain respond as if a preprogrammed pattern of motion
were taking place. For someone suffering from pattern overload, this may
present itself as an unknown strain or spasm in an unrelated region.
The easiest ways to avoid developing pattern
overload is to avoid machines that don’t fit your body, and if you’re going to
use machines, avoiding relying on them, and alternat machine exercises in and
out of your routine. Doing so will at least decrease your chance of injury
because you're allowing a healing response in the fatigued or traumatized
tissues related to a specific pattern of motion.
Common sense would suggest never training an
area experiencing joint or muscle pain as well. Pain always equals inhibition,
and if you train in pain, you can rest assured that the muscles crossing any
joint in pain are being shut off, resulting in progressive instability of the
joint(s) related to that muscle.
If you have any questions about the use of
machines in your own, or a clients weight training program, feel free to
contact me at ben@paramounttraining.ca. I'm available for online consulting and
personalized program design, as well as one on one training if you are located
in the Greater Toronto Area (GTA).
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