Constant vs.
Variable Resistance
When resistance remains constant, muscular
tension is greatest at the range in which the resistance's line of pull is
perpendicular (90 degrees) to body's lever arm, as relative continuous muscular
tension is not required throughout the full range of motion of an exercise. As
a result, there ends up being a relatively large difference in terms of muscle tension
that takes place throughout the range of motion, the degree of which can vary
depending on the length of range.
The relationship between muscular tension and length
of range of motion is inversely proportionate:
The shorter the range of motion – the greater
percentage of the range in which the muscle tension is relatively continuous,
ex: calf raise, wrist curl – the muscles remain under very high levels of
tension throughout the range of motion as a result of the minimal range
The greater the range of motion – the lesser
percentage of the range in which the muscle tension is relatively continuous,
ex: squat, deadlift, bench press, pull-up – the muscles are not under very high
levels of tension through the majority of the range of motion as a result of
the extended range
Variable resistance requires relative
continuous muscular tension throughout the full range of motion, as long as the
resistance matches the exercise’s strength profile.
Strength Profiles
Gravity dependent, free weight exercises have
their own specific strength profile (AKA resistance curve), which describe
their characteristic change of force throughout the range of motion, and can be
classified under one of three categories – ascending, descending, concave/bell-shaped.
Ascending Strength
Curve
The tension curve in which the muscular tension
required decreases as leverage increases, and the movement becomes
progressively easier throughout the range of motion until the end of concentric
range (most compound extension oriented movements fall under this category, as
they generally place the targeted muscle under the greatest amount of tension
at the beginning of concentric range: ex, bench press, squat, deadlift)
Descending
Strength Curve
The tension curve in which the muscular tension
required increases as leverage decreases, and the movement becomes
progressively harder throughout the range of motion until the end of concentric
range (most compound flexion oriented movements fall under this category, as
they generally place the targeted muscle under the greatest amount of tension
at the end of concentric range: ex, pull-up, chin-up, rows)
Concave/Bell-Shaped
Strength Curve
The tension curve in which the muscular tension
required increases then decreases, as leverage decreases then increases, and
the movement becomes progressively harder and then easier. Many gravity
dependent exercises tend to have a bell shaped resistance curve where muscular
tension is greatest in middle of the range (most free weight isolation
movements fall under this category, as they generally place the targeted muscle
under the greatest amount of tension in the middle of the range of motion: ex,
arm curls/extensions w/barbells or dumbells)
And Why Is This
Important?
In a perfect world, the resistance would increase,
decrease, or both, throughout the range of motion to match the strength profile
of the exercise being performed, and effectively overload the entire strength
curve by gradually increasing for movements with an ascending strength profile,
gradually decreasing for movements with a descending strength curve, and gradually
decreasing then increasing for movements with a concave/bell-shaped strength
curve. Since we don’t live in such a world, muscles are undertrained under
normal conditions, as the amount of resistance needed to overload the entire
strength curve is limited by how much force can be generated in the most
disadvantageous range of the movement.
Bands And Chains
Variable resistance can be applied with the use
of resistance bands, or lifting chains, to match the strength profile of
movements which follow an ascending strength curve, to create a more complete
movement, so that relative continuous muscular tension is required throughout
the range of motion. Unfortunately, movements which follow a descending, or
concave/bell-shaped strength profile, don’t have this luxury, therefore the only
opportunity to perform movements in which the resistance matches the strength
profile of the exercise is to use variable resistance machines specifically designed
for this purpose.
Aside from creating a more complete movement by
overloading the entire strength curve so that relative continuous muscular
tension is required throughout the range of motion, the variable resistance
provided by bands and chains offers a few other significant benefits:
·
Chains, and bands, are valuable tools for teaching the nervous
system the concept of acceleration. Under normal conditions the amount of force
needed to overcome the resistance decreases as leverage improves, and even if
the intent is to lift with maximal acceleration, because more force can be
produced with improved leverage, the weight is relatively lighter at the end of
concentric range resulting in a phase of deceleration as range comes to an end.
In fact, the deceleration phase during an explosive lift can be as long, if not
longer, than the acceleration phase, as greater acceleration requires greater
deceleration, and this can have adverse effects by essentially teaching and
reinforcing the concept of deceleration. Chains, and bands, all but eliminate
the deceleration phase at end range because the amount of force needed to overcome
the resistance increases in direct proportion to one another. And how does the
nervous system respond to the variable demand? By relying on the high threshold
motor units! Do this enough times and over time the nervous system will begin
to preferentially recruit those motor units, thus increasing the quality of the
rest of your training because of the carryover effect.
·
Chains, and bands, increase the average load per set, and
increase the time under maximal tension. Because chains, and bands, overload
the entire strength curve, the resistance at the end of concentric range is
generally far greater than would otherwise be possible under normal conditions.
Chains vs. Bands
The differences between chains and bands are
minimal, but each ultimately provides a much different stimulus. While chains
and bands similarly increase the amount of resistance felt, bands require
greater eccentric demands, as they attempt to rapidly pull the bar down into
the floor. Because of this, chains are generally preferred over bands when
training for power, as they are much easier to control when lifting explosively,
while bands may positively influence strength development to a slightly
greater degree because of the enhanced eccentric component.
Loading
The whole purpose of matching the resistance to
the strength curve is to ensure the heaviest weight possible is being applied
throughout the range of motion, since generally much greater loads can be
handled at the end of concentric range. Therefore, as far as loading is
concerned, the resistance at the end range should represent over 100% of full
range max. This is perhaps the greatest benefit which chains, and bands, can
offer – the use of supramaximal weights, albeit through a limited range.
Generally a 20-30% discrepancy between top range, and bottom range, loading is
ideal: ex. bottom range loading is equivalent to 80% of 1RM, top range loading
is equivalent to 105% of 1RM. If the discrepancy is either too great, or too
little, much of the training effect is lost.
Reverse Bands
The greatest difference between chains and
bands is that bands offer far greater versatility. While chains are only
capable of opposing gravitational forces, bands can oppose force from virtually
any angle – even from above. While bands increase eccentric stress, reverse
bands decrease it, so even with the same relative load at the top and bottom
range of motion, the eccentric stress is drastically different. For this
reason, reverse bands are preferred for those with tender shoulders when
pressing, as they provide the most assistance in the most vulnerable range,
which allows for the movement to continue being trained (with maximal loads), to
prevent gains from being lost by removing it from the program all together.
A Word Of Caution
The variable resistance provided by chains, and
bands, is very neurologically demanding, as the nervous system doesn’t have the
opportunity to put things on ‘cruise control’ for much of the range of motion
that would otherwise be possible when resistance remains constant. Because of
this, it’s best to cycle the usage of these highly intensive tools in, and out,
of a training program, to prevent overworking the body’s capacity to recover
from the workload, an example of a workout-to-workout progression looking like
this:
Workout 1: 4 x 6-8 – NO CHAINS OR BANDS
ADDED
Workout 2: 3-4 x 4-6 – WITH CHAINS
Workout 3: 3-4 x 4-6 – WITH BANDS
Cycle can be repeated 2-3 times, then it’s best
to cycle off chains and bands for a few weeks because of the increased neural
demand.
BEST EXERCISES TO
IMPLEMENT THE USE OF CHAINS, BANDS, AND REVERSE BANDS
Squats (front squat, back squat)
Deadlifts (standard, sumo, Romanian)
Good Mornings
Bench Press (All forms of presses can be used
very effectively with chains/bands/reverse bands)
*Decline Triceps Extension
Chains, and bands, are best implemented with
exercises in which the bar path is as close to vertical as possible. If the bar
path shifts, the resistance applied by the chains or bands can negatively
affect the motor pattern, thus reducing the effectiveness of the movement, as
well as the ability to carry over the gains made using the chains and bands.
Bands however, can be effectively implemented with many machines because their
line of pull can vary in a way that is not possible with chains, due to
gravity.
*With a decline bench, the bar basically
travels vertically as the arms are extended and flexed, as opposed to the flat
angle which has more of an ‘arc’ path which, as described above, can negatively
affect motor pattern development.
If you have any questions about strength
curves, and how to use chains and bands to increase strength, 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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