Dynamic vs Static
A dynamic
contraction is one in which there is a change in muscle length, as it either
lengthens (eccentric contraction), or shortens (concentric contraction), while
producing force. A full range repetition consists of both, as the involved
musculature produces enough force to shorten and ‘overcome’ the resistance, before
reversing the motion, while still producing enough force to ‘yield’ the rate in
which resistance lowers, as the muscles lengthen.
A static (isometric)
contraction refers to a muscle generating force without physically seeing a
change in its length – the fibers may actually shorten as they produce force,
but the relative joint angle remains the same.
Overcoming /
Yielding
Much like that are
two types of dynamic contractions (concentric, and eccentric), there are two
types of isometric actions:
·
Overcoming – force is applied but is unable overcome the resistance,
as it remains still. A practical example would be trying to press/pull a bar
through the pins in a power rack.
·
Yielding – the resistance unable to overcome the force being
applied, and remains still. A practical example would be holding a weight and
preventing it from succumbing to its gravitational pull.
Even though the
physical action is identical, and the outcome is the same (no change in muscle
length/joint angle), both techniques will not have the same effect because the
neural pattern in both cases will be different. The intention to overcome may
have a considerably larger impact on concentric strength, while the intension
to yield may have a considerably larger impact on eccentric strength, and overall
muscle mass.
The Benefits
While isometrics are
likely not as effective at stimulating size or strength gains as concentric
and/or eccentric training, they do come with their own distinct benefits which
cannot be duplicated dynamically.
·
Greater force production – Because isometrics (overcoming, in this
case) require less motor skill, it’s possible to recruit almost all motor units
when performing an isometric contraction. This simply isn’t possible when
performing a dynamic movement because greater motor skill is needed to
stabilize the load, and this affects the neural drive to the targeted muscles
since the nervous system must coordinate the activation of other muscles to
secure the body. Stability, which is a prerequisite to maximal force
production, is all but eliminated when attempting to push/pull an immovable
object, which facilitates maximal exertion.
·
Improved neural drive – Because there is a greater level of
activation when performing isometrics (overcoming, but yielding to some degree
if supporting a supramaximal load), they can be used to acutely (performed at
the beginning of the workout as a means of activating the muscles being trained
that day), and chronically (by using them over a sustained period of time),
improve the capacity to recruit more motor units during dynamic actions of the
same nature, thus enhancing the quality of traditional training.
·
Greater time under maximal tension – Because ‘strength’ is highly
influenced by the total time under MAXIMAL tension, increasing the amount of
time the muscles spend under maximal tension can increase strength gain
potential. When performing a dynamic exercise, intramuscular tension is at its
peak for roughly ¼ of a second, to a ½ of a second during the concentric repetition
(due to improved leverages, and the fact that the velocity and acceleration
imparted to the resistance limit the amount of force needed to move it – in
fact, too much acceleration can result in the nervous system having to
decelerate the load, which can hamper strength gain potential), but when
attempting to push/pull an immovable object, or resist a supramaximal load from
being lowered, maximal tension can be sustained for at least 3 full seconds,
and up to anywhere between 6-12 seconds.
·
Physical demand is low – Even with maximal exertion, the energy
expended during isometrics is minimal at best, meaning it’s possible to reap their
benefits without interfering with the rest of the workout, or hindering
recovery.
·
Specific ranges of motion can be overloaded – Because of the nature
in which isometrics are performed, they can be used to overload specific ranges
of motion, which otherwise wouldn’t happen, unless deliberately performing
partials. Because the amount of weight that can be used for any exercise is
limited by how strong you are at the weakest range of motion, the muscles are
not fully stimulated for the majority of the range of motion. Isometrics can be
set up to target specific ranges of motion so that the muscles are under
maximal tension at ranges in which they wouldn’t be when performing the same
pattern dynamically.
However, because
strength is gained in the range it is trained, and muscle length does not
change, the strength gained occurs chiefly at the joint angles in which the
stress is applied, although 20-50% of the strength gained will carryover
roughly 20 degrees each way. So even though isometrics can facilitate size and
strength gains, without a concurrent dynamic program, progress will be suboptimal.
Like every other
technique or method, the body adapts to the usage of isometrics, therefore they
should only be used for short periods of time (gains may taper after 6-8 weeks)
when progress has slowed down and a rapid improvement in strength is needed, or
to prevent losing strength or size during periods when the volume needs to be
reduced to allow for recovery, or are on a time constraint.
Practical
Application – Time Under Tension Dictates The Training Effect
Since there are no
actual reps performed when doing isometrics, the training effect is realized as
a result of the time in which tension is applied.
For Strength – 3-6 seconds, 100-110% of max if yielding
Using isometrics to
increase strength is similar in effect to dynamic methods consisting of 1-5
reps, with 85-100% of max. Isometrics for this purpose are better used as an
activation/potentiation method prior to dynamic strength work, rather than a
pure strength building method, because they can improve the capacity to recruit
and synchronize motor-units (intramuscular coordination) in dynamic movements.
Possibly the best way to incorporate isometrics for this purpose is with *contrast
training.
*Contrast training consists
of performing a ‘heavy’ set to activate the nervous system, so by ‘contrast’
the ‘light’ set feels lighter than it is, thus facilitating improved
performance by way of allowing a slightly greater load to be used, or an extra
rep to be performed than would otherwise be possible.
Because supramaximal
loads are needed to get the same effect, isometrics of an overcoming nature (pushing
or pulling against pins or an immovable resistance) are much more practical and
safer, and thus is the preferred method, although both yielding, and
overcoming, can be used effectively.
It’s important to remember
to use multiple positions because the effect occurs specifically at the joint
angle being trained, ex: 2 sets at bottom range, 2 sets at mid-range, 2 sets at
top range, or vice versa.
For Size – 20-60
seconds, 50-80% of max if yielding
Using isometrics to
increase size is similar in effect to dynamic methods consisting of 8-12 reps,
with 70-80% of max. Isometrics for this purpose are better used as a means of
extending the time under tension following dynamic strength work, rather than a
pure muscle building method, because of the very significant growth stimulus
placed on all of the muscle fibers. Possibly the best way to incorporate
isometrics for this purpose is to pause during the final eccentric repetition
for as long as possible – either at the mid-range, or stopping at 3 different
ranges that are 20-40 degrees apart (bottom range, mid-range, top range).
This is a very
taxing method and shouldn’t be performed for more than one exercise per muscle
(if used for all sets) or for more than one set per exercise (if used for all
exercises).
Because multiple
pieces of equipment are needed (primarily a power rack) to get the same effect,
isometrics of a yielding (holding the same weight used dynamically) nature are much
more practical and effective, and thus is the preferred method, although both
overcoming, and yielding, can be used effectively.
For Performance –
(Ballistic) Dynamic/Isometric
*Not to be mistaken
with iso-dynamic, in which an explosive action is preceded by an isometric
pause to limit the force contribution from the stretch reflex, and any stored
elastic energy from the eccentric repetition.
(Ballistic) dynamic-isometric
refers to pushing/pulling against an immovable object for a very brief period
of time (one or two seconds) while trying to reach peak force output as fast as
possible to improve starting-strength, and the rate of force development. Due
to the nature of the exercise, this can only be done with ‘overcoming’
isometrics — the nature being to produce maximum isometric tension in as
little time as possible.
Other Applications
Aside from enhancing
neural drive and potentiating the nervous system, or prolonging the time under
tension, isometrics can also be used as a stand-alone method, in which they are
not preceded or succeeded with a dynamic movement of the same pattern, or to
pre-exhaust a muscle to enhance the mind-muscle connection during the
succeeding dynamic movement, and thus enhance the quality of performance.
Stand-Alone
Parameters
·
Sets: 1-5 per position (perform all sets for each position before
moving onto the next)
·
Positions: 3 (mid-range, bottom range/full contraction, top range/near
full stretch)
·
Duration: 3-6 seconds for strength, 9-12 is also acceptable, 20-60
for size
·
Yielding Load: 90-110% for strength, 70-80% for size
·
Rest: 60 seconds, since isometrics are not energy expensive
Pre-Exhaust
Parameters
Because of the
limiting effect pre-exhaustion can have on strength gains, this method is best
used as a tool to stimulate muscle growth only. Isolation exercises should be
the only consideration, as they mechanically place the targeted muscle under
the most tension, while limiting the force contribution of supporting muscle
groups. This variation can produce rapid gains in muscle size and is especially
useful in correcting specific aesthetic weaknesses.
·
Sets: 1-3 per position (perform all sets for each position before
moving onto the next)
·
Positions: 3 (mid-range, bottom range/full contraction, top range/near
full stretch)
·
Duration: as long as possible (aiming for 45-60 seconds)
·
Yielding Load: 90% (or 3 rep max)
·
Rest: 60 seconds
Practical Example
With Biceps
*The preacher bench
is most practical for the iso since it provides the most stability, but any
curl variation can be used for the dynamic portion of the superset.
A1) Isometric
preacher - Elbows 90 degrees for max time
A2) Arm curl (barbell,
dumbell, cable, etc.)
*No rest between A1
and A2, and 45-60 seconds rest between both rounds (2 sets only)
B1) Isometric
preacher - Elbows almost fully flexed for max time
B2) Arm curl (barbell,
dumbell, cable, etc.)
*No rest between B1
and B2, and 45-60 seconds rest between both rounds (2 sets only)
C1) Isometric
preacher - Elbows almost fully extended for max time
C2) Arm curl (barbell,
dumbell, cable, etc.)
*No rest between C1
and C2, and 45-60 seconds rest between both rounds (2 sets only)
If you have any
questions about how to implement isometrics to increase size or 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).
that was so helpful
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