While there are 3 types of muscular
contractions – concentric, isometric, eccentric, in which muscles produce force
while either shortening, lengthening, or remaining the same length, there are
only 2 types of intended muscular actions – overcoming, yielding.
Concentric contractions consist of a
shortening, overcoming action, in which the intent is to produce enough force
to overcome the amount of resistance placed on the muscles, while eccentric
contractions consist of a lengthening, yielding action, in which the intent is
to produce enough force to yield the lengthening action of the muscles, while
isometrics can be of an overcoming, or yielding nature (the intent to shorten,
without an actual change in length occurring being of an overcoming nature,
while the intent to prevent lengthening, without an actual change in length
occurring being of a yielding nature).
In terms of motor patterns and motor unit
recruitment, overcoming actions follow a hierarchy in that motor units are
recruited as needed from smallest (and weakest) to largest (and strongest)
based on the perceived demand. The greater the demand is perceived to be (which
can be consciously controlled based on intention), the greater amount of motor
units that will be recruited.
Yielding actions do not follow this hierarchy,
as they are perceived as potentially dangerous and threatening by the nervous
system, as it has no clue as to why a muscle is being stretched under load, all
it knows is it that to prevent a potentially catastrophic injury, it must favor
the recruitment of the muscle fibers which are capable of producing the highest
levels of force – the fast twitch muscle fibers (which also happen to have the
greatest size and strength potential).
On a pound for pound basis, there are less total
fibers recruited during a yielding action in comparison with an overcoming
action, resulting in higher forces being exerted on the fewer motor units recruited,
which will encourage greater biological adaptations. Therefore, the stress
per fiber is greater, resulting in greater muscle damage (micro-trauma/tearing),
and this happens to be why eccentrics cause more discomfort and soreness in the
trained musculature during the acute recovery period (AKA, DOMS – delayed onset
muscle soreness) than concentrics and isometrics.
The soreness and discomfort produced from
eccentric training is commonly, and incorrectly, associated with strength and
size gains, ultimately leading to ineffective usage of eccentrics. Size and
strength gains are primarily the result of the activation of cell signalling
via several pathways (EPK, PKB, etc), as well as the activation of the mTOR
pathway, and the production of local growth factors like IGF-1, not because
muscles are damaged, it’s more so that muscles just happen to be damaged in the
process that triggers this cascade of events. In fact, excessive damage
resulting from a high volume of eccentrics can actually retard the repairing
and rebuilding process, so the use of eccentrics must be progressed carefully
because of the greater toll they take on the body.
To reap the full benefits of eccentric training,
a small amount of eccentric overload is needed (enough to stimulate, but not so
much that you cause excessive damage). When overloaded, eccentrics provide the
greatest neural adaptation (which is the primary cause of strength gains)
because they force the nervous system to learn to increase its capacity to
recruit motor units faster, and not just any motor units, the high threshold
motor units, since they are the ones which are preferentially recruited during
eccentric contractions. This increased recruitment and stimulation of fast
twitch muscle fibers is the greatest benefit that eccentric loading can
provide, and the benefits of increased capacity to recruit the fast twitch
muscle fibers carry over to all other types of training.
Because of the nature of the motor pattern,
most people can generally handle upwards of 30% more weight eccentrically than
concentrically (up to 130% of concentric max, although it’s been suggested that
a well trained individual may be able to handle upwards of 175% of concentric max
eccentrically). Therefore, a load provides sufficient overload concentrically
will not have the same overloading effect eccentrically (because muscles are essentially
stronger eccentrically, they need to handle greater loads to get the same
effect).
For example, if a muscle is roughly 30%
stronger eccentrically, this means:
·
100% of concentric max will provide roughly 77% of
eccentric overload (77 + 30% = 100.1, for those who did the math and are
thinking that things aren’t adding up. 30% is relative, and differs based on
whether it’s being added to, or subtracted from)
·
90% of concentric max will provide roughly 69% of eccentric
overload
·
80% of concentric max will provide roughly 62% of eccentric
overload
·
70% of concentric max will provide roughly 54% of eccentric
overload
Because a load of at least 70% of relative max
is needed to provide sufficient overload, the weight needs to be at least
equivalent to 91% of concentric max (70 + 30% = 91):
·
97% of concentric max will achieve roughly 75% of eccentric
overload
·
104% of concentric max will achieve roughly 80% of
eccentric overload
·
110% of concentric max will achieve roughly 85% of
eccentric overload
·
117% of concentric max will achieve roughly 90% of eccentric
overload
In some cases the margin may be greater 30%,
while in others it may be smaller, but in either case it’s painfully obvious
that a greater load is needed than that which is being used to overload a
muscle concentrically, to overload a muscle eccentrically. Most people fail to
understand the concept of overload, or misinterpret what it actually means, and
end up failing to take advantage of the opportunity for gains that eccentric
training offers.
With concentric training you can overload the
muscle or increase the amount of tension the muscle is under, by increasing the
perceived demand (as stated earlier), irrespective of how much weight in
relation to maximum is being used, which is done by consciously trying to lift
the weight with maximum effort. With eccentric training however, overload is
directly related to the weight in relation to maximum that is being used, not
the speed in which you allow the muscles to be lengthened under load. The only
implication that the speed in which a weight is lowered has is to quantify
progression, and gauge whether or not it is safe to perform another rep.
Since anything under 70% of relative maximum
will not provide optimal overload, and loads need to be in excess of 90% of
concentric max to have any real value from an eccentric overload perspective,
this doesn’t really allow for many practical applications, because loads at
that level of intensity don’t allow for many reps to be performed (obviously
loads in excess of 100% of concentric max don’t allow for any concentric reps
to be performed).
In most cases 91% of concentric max represents
around ones 4 rep maximum, meaning that it likely isn’t possible to perform 4
reps at that intensity twice (or more) during the same workout (if you can
duplicate your performance, it likely wasn’t a true rep max).
Also needing to be taken into consideration is
that a maximum performance generally doesn’t include an enhanced eccentric
component, as the increased time under tension undoubtedly affects the ability
to perform the maximum amount of reps at a given intensity. The longer each rep
takes to complete, the less total reps that can be performed, regardless of the
load. Therefore, to perform the same amount of reps while emphasizing the
eccentric component of each rep in an attempt to maximize overload, less weight
is going to have to be used, but this is not a viable option because lowering
the load in favoring of increasing the time under tension does not provide
sufficient eccentric overload.
This leaves sets of 3 reps or less, using loads
in excess of 90% of concentric max, as the only real means of practically
applying eccentric overload, but the heavier the weight is in relation to
concentric max, the greater toll it takes on the neuromuscular system, and the
less likely you’ll actually be able to lift it through the concentric range to
perform a second or third eccentric repetition. Therefore, process of
elimination leads us to one logical solution, and that is to only bother focusing
on performing one rep at a time, using as much weight as possible, and lowering
for as long as possible, repeating that sequence no more than 5 times per
workout (3-4 being optimal) for the trained musculature (anymore than 5 reps
with loads in excess of 95% of concentric max is when the risk begins to
outweigh the reward anyway). The question now becomes how to implement these
3-4 eccentric overload reps into a program?
Effective
practical application for eccentric overload
When?: At the beginning of the workout is when
you’ll be able to handle the greatest loads, for the greatest duration, which
is the whole point of overload in the first place. The fast twitch fibers that are
recruited during eccentric overload, which may not normally be recruited, set
the stage for the rest of the workout as they facilitate the use of greater
loads for concentric work that follows, which further stimulates the activated
muscle fibers.
How?: The 3-4 overload reps can be used as standalones
performed back-to-back-to-back(-to-back) before moving on to the rest of the
scheduled workload, or used concurrently with concentric work.
When used concurrently, the eccentric
repetition can be performed as the first rep of the set, at which point the
‘overload’ is removed, the same way you would when performing a drop set, and
the rest of the reps are performed as scheduled, or alternated back and forth
as part of a contrast method. In either case the goal is to be able to use more
weight than you normally would for the same amount of reps, or perform an extra
rep with the same load you had planned to use, because of the additional fast
twitch fiber activation. An example of the eccentric overload drop set looking
like this:
Rep 1: eccentric rep w/ 100-110% of concentric
max, concentric rep with 90% of concentric max
Rep 2: full range rep w/ 90% of concentric max
Rep 3: full range rep w/ 90% of concentric max
Rep 4: full range rep w/ 90% of concentric max
It should go without saying that a power rack
is needed, and the only exercises suited for this type of work are those in
which a barbell is used, in which case you would simply lower the bar onto the
rack, remove the eccentric overload, get back in and finish the set. The major
difference with a contrast method is you do not finish the set right away after
performing the eccentric overload. Obviously if you have a training partner
this is much easier and a lot more practical.
If performing more than 4 sets, staggering the
eccentric overload reps (since you don’t want to be performing more than 4
eccentric overload reps) by combining the drop set method above with the
contrast method above and alternating between sets which begin with an
eccentric overload rep with a traditional set in which no eccentric overload is
added, is best. An example looking like this:
Set 1: eccentric overload on first rep
Set 2: no eccentric overload
Set 3: eccentric overload on first rep
Set 4: no eccentric overload
Set 5: eccentric overload on first rep
Set 6: no eccentric overload
Intensity?: While some muscles may be capable
of handling 30% greater loads eccentrically than concentrically, it isn’t
absolutely necessary to lift such great loads to reap the benefits of eccentric
overload and fast twitch fiber recruitment. As long as you’re using over 90% of
concentric max you’ll get the full effect. If using a drop set, or contrast
method, aim for 10-20% more weight for the eccentric repetition than what you
will be using concentrically (unless using the overloaded eccentric to activate
the fast twitch muscle fibers prior to speed/dynamic work which is typically performed
with 45-55% of max, and 10-20% more than that won’t do much in terms of
providing any eccentric overload whatsoever).
Work:rest? Because of the high intensity nature
of eccentric overloads, they should not be used exclusively, but rather for 3
weeks at a time at the most, with a better option being to spread them out over
several weeks using a 2:1 ratio in terms of ‘regular’ training to eccentric
overload training. Also, the results from eccentric training have a delayed
effect, so 3 weeks should be given between the last eccentric overload session
and any testing done to gauge progression (this also means that eccentric
overload training should cease at least 3 weeks before an event in which
strength need to be demonstrated).
This type of training is not suited for beginners,
or those with relatively little training experience, as it can damage the
connective tissue, which in turn increases the risk of muscle injury. Therefore
one should have at least two full quality years of training under their belt
before attempting this type of training, as it’s not even remotely necessary at
that stage in the game to rely on a method like this to get results.
Progression: As stated above, the only implication
that the speed in which a weight is lowered has is to quantify progression, and
gauge whether or not it is safe to perform another rep, meaning that there
should be a predetermined amount of time in which the weight is to be lowered,
and if the weight is lowered faster than the predetermined time, that would
indicate that the load is too great. The preset time should be determined by the
amount of weight being used and the range of motion of the movement (the
greater the range of motion, the longer the eccentric should be), with the goal
being to work up a 10 second yielding action, but if it is possible to lower
for longer than that, then it’s time to increase the weight.
A word of caution for athletes
Eccentric actions can be subdivided into two
separate categories: slow eccentric actions (which is what the content up to
this point has centered around), and fast/rapid eccentric actions (which need
not be neglected for those training for sport).
Exclusively performing slow eccentric actions increases
the possibility of decreasing the ability to generate maximum force instantly, therefore
usage of them is best suited early on in a periodized training
program because of the delayed training effect, and because of the burden
the take on the nervous system. In this case, fast eccentrics by way of
plyometrics should used closer to the competitive period.
Eccentric strength, rather the ability to
produce force while the involved musculature is lengthening under load, or
decelerate, is of paramount importance in many different sports that require
advanced jumping, and change of direction ability, such as various
track and field events, football, soccer, basketball, downhill ski events,
gymnastics events, and figure skating.
Slow eccentric based movements are those done
with a barbell as stated above (squats, deadlifts, various presses), but fast/rapid
eccentric movements generally require no more than bodyweight (various jumps with
the emphasis being on landing, depth push-ups – basically any movement in which
the nervous system receives input and is required to instantly react by
producing force as the muscle rapidly lengthens). Both types of eccentric
loading have a place in a well rounded training program, although when they are
used is highly dependent on the individual’s goals.
For simplicity and convenience, fast eccentrics
can be combined slow eccentrics as part of a complex. The theory here is that
the slow eccentrics tap into the high threshold motor units while the
fast eccentrics create muscle fiber damage that leads to the growth
of fast twitch muscle fibers while maximizing the neural adaptation.
In this case a set of slow eccentrics (using
the eccentric overload technique provided above, or even just a normal set
within your 1-3, or up to 5, rep range) would be followed by an exercise that
is plyometric in nature. A practical example would be squats followed by drop
jumps (aim to perform double the amount of drops than squats per set, ex. 3
reps for squats, followed by 6 drops). The height of the drop is determined by
the height of the rebounding jump – increase the height of the drop until there
is no longer an increase in the height of the rebounding jump.
If you have any questions about how to properly
overload eccentrics, 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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