Lifting to Fail?
by Matthew Perryman
Neural Factors of Fatigue and How to Manage Them
Most of us don't go to the gym to fail, right? Of course not. We're there to
succeed and reach our goals. At least, I hope that's why'you guys there to pick
up chicks, get out of the power rack. Anyway, for the success-minded athlete,
the concept of failure sure is bandied about a lot by those 'in the know.'
Muscular failure, if you haven't guessed by now, is the issue at hand.
For some schools of thought, achieving failure (or not, in some cases) is the
defining point in determining whether or not a program will be successful. It
seems that a great many arguments in the strength training world revolve around
that single point. One doesn't have to stray far to see this. Fortunately this
article is not one of those arguments. Rather, I've chosen to inform instead of
bicker.
HIT Upside the Head
The concept of achieving absolute muscular failure, or the so-called 'momentary
muscular ability,' can trace its origins back to the 1970s and the HIT school of
bodybuilding. The HIT philosophy took its shape around the theories of Arthur
Jones and Dr. Ellington Darden, and was personified by the late Mike Mentzer, a
bodybuilder on par with Arnold in his prime.
A system claiming to value logic, knowledge, and empiricism, HIT can seem
bullet-proof to many. Mike Mentzer's elite-level bodybuilding physique, built by
HIT's methodology, only cemented this claim. Indeed, to its credit, it does
encompass a general framework and set of principles that can be excellent for
building muscle and developing general strength qualities when incorporated
properly.
Unfortunately, a bad thing happened to HIT. Be it through logic, the
salesmanship and business practices of Jones, or some measure of all, HIT was
based upon a fundamental flaw: the idea that achieving muscular failure was not
only desirable, but an absolute necessity for achieving muscular hypertrophy.
HIT's measure of intensity, unlike the remainder of the exercise science world,
is based on subjective effort. In other words, 100% intensity is pushing
yourself to the point where you cannot achieve a full rep without assistance, a
state referred to as concentric failure. The problem is that this measure of
intensity (properly called intensiveness, a measure of subjective effort) has
about as much to do with muscle growth as a good microbrew.
As later research into physiology would show, concentric failure is a
predominantly neurological phenomenon. It doesn't directly cause hypertrophic
increases, though it can correlate with them. In simple terms, failure isn't a
requirement for getting bigger.
This leads to a whole host of problems with the rest of HIT's prescriptions.
Since training so intensively on a regular basis is taxing too many of the
body's systems, the workouts must necessarily be infrequent. Not only must the
frequency decrease as the lifter becomes stronger and more advanced, but the
volume used in each session must also decrease. This runs 180 degrees counter to
what the bulk of research tells us about athletes, who must actually increase
the total training stimulus as they become more advanced.
These assertions were supposedly based upon raw logic, and in the absence of any
information to the contrary, it's perfectly understandable how Jones and company
came to those conclusions (though it's a widely known rumor that Jones created
the one-set-to-failure protocol for which HIT is most famous as a means of
getting people out of his Nautilus gyms as quickly as possible). However,
there's been a lot of research over the past few decades that has given us new
insight into the body's processes, much of which overrides the logical
extrapolations used by Jones and company. The HIT camp generally seems unwilling
to change with the times however, for whatever reasons.
The point of this article is not to pick on HIT, though. HIT was discussed
merely to provide a very convenient and easily recognized example to introduce
the true subject. Specifically, I want to discuss just what failure is, its pros
and cons, and how to use it effectively as a part of your bodybuilding and/or
strength training program.
How to Fail in Your Training
Muscular failure is actually a fairly complex topic. Strictly speaking, there
are three types of muscular failure: concentric, isometric, and eccentric.
Concentric failure is exactly what I used in the example above: the inability to
complete a repetition without external assistance (be it a partner or cheating).
Isometric or static failure is the inability to hold a load in place. Eccentric
failure is really more of an abstraction'as a thought experiment it can occur,
but in practice it really can't without an injury. Concentric failure is the
commonly-accepted definition of failure used by those espousing the merits of
achieving maximum effort on every set.
In order to understand the double-edged sword of concentric failure, a few
points have to be considered. Firstly, what is the duration of the set? For the
most part, failing on two reps will be similar to failing on six from a
physiological standpoint. But what about twelve? Twenty? There's a 'strength
zone' of reps, generally between the 1RM and 10RM, where failure can be
primarily attributed to neurological factors. Beyond this, metabolic factors
begin to take more and more precedence'it becomes a test of endurance instead of
strength. For the purpose of this article, we'll be considering the issue of
failure as it applies to the strength zone.
So, what does the nervous system have to do with bodybuilding? Quite a bit. The
nervous system is responsible for generating the impulses that cause all muscle
contractions. The muscle itself is composed of multiple fibers, which are
assigned into slow-twitch (ST) and fast-twitch (FT) categories. Each fiber is
connected to a motor neuron originating in the brain. A motor neuron and all the
fibers it connects to is called a motor unit (MU).
Motor units have activation thresholds'any stimulation from the nervous system
below that threshold will not cause them to activate. Motor units are recruited
according to the size principle, which more or less tells us that ST fibers are
recruited before FT, and the FT fibers with the highest output are the last to
be used. The highest-threshold MU's require large amounts of tension to recruit.
There are a series of neural afferents, called proprioceptors, in muscle tissue
that continuously provide feedback to the brain on the level of tension present
in the muscle and allow the brain to adjust its output. This process is linked
closely with cognitive control over motor function, and is capable of making
very fine distinctions with regards to loads, force output, and rate of force
development. Proprioception is responsible for the 'feel' of an exercise.
As a set progresses, the smaller MU's begin to fatigue. In order to keep up with
the demands imposed upon the muscle, the nervous system begins changing things.
Based on feedback from proprioceptors in the muscle, the nervous system
increases the frequency of impulses (rate coding), and begins to recruit MU's
synchronously. Synchronous recruitment means that the nervous system will
recruit every potential MU at once, instead of the usual asynchronous fashion
(33). Failure occurs when the pool of MU's recruited to lift the weight fatigue
and the nervous system increases its output to activate other MU's to take up
the slack. This is more or less the same thing that occurs when achieving a
maximal attempt. Due to the principle of specificity, the body will adapt to
these firing patterns. This process of failure is both a good thing and a bad
thing.
Bad news first. When consistently exposed to high-frequency impulses, the CNS
has the peculiar trait of inhibiting its own output (12, 14, 17, 18, 19, 20, 21,
28, 29). This is theorized to be a protective mechanism, since consistent
exposure to a high-intensity stimulus will be damaging to a neuron much the same
way it would be to a muscle fiber, or any other tissue for that matter.
Biological tissues are really nothing more than a means of transforming chemical
energy into other forms; in the case of muscles, it becomes mechanical force,
while in neurons it becomes an electrochemical impulse. If you demand too much
and over-stress any of those tissues, they will become damaged and require a
period of down-time in order to recuperate. The act of generating action
potentials over and over, as is the case when maximal 'push' is being put into a
lift, is about the same thing as asking your muscle to perform 6 sets of 10 reps
with 20 seconds of rest. It's going to chew them up.
Up until recently there wasn't a whole lot of research in this area to draw
from. Lately though a large amount of research dealing with the topic of
cortical motor output (neural drive) has been published, and it's only
reinforcing the idea that every period of high-intensity work requires a
corresponding down-time for recovery (1-12).
Neural drive and fatigue is also directly linked to the individual's state of
arousal. It's thought that this is because many of the structures that are
responsible for motor output are the same structures that are responsible for
emotion and arousal in humans, such as the basal ganglia and the reticular
activating system (28). Having to get 'psyched up' for a lift week after week
can contribute to the neurological fatigue due to that fact. Many former Eastern
bloc countries implanted this knowledge when designing their routines, having
athletes avoid emotionally-taxing lifts as much as possible. They make a
distinction between the 'training max' and the 'competition max,' with the
former requiring little if any mental preparation. The arousal factor will prove
to be the most telling in terms of how severely taxed the CNS is at any time, as
focus and motivation can be easily determined by most people (not to mention
manipulated by various supplements and well, 'other' substances).
You've heard of people talking about 'overtraining' the CNS? This is your boy
right here. While there appears to be some benefit to switching up the
exercises, as recommended by Westside for example, this may be because the body
hasn't accommodated to the movement, and a period of lowered intensity is
necessarily brought about. A period of lowered intensity is a necessity after
periods of high-intensity work, and it's not all for muscular reasons. The mind
needs a break as well, which is why one of the most common indicators of
overtraining is lack of motivation to exercise.
Beyond the central fatigue that can develop in the brain, damage of a sort can
also happen in the peripheral nervous system, at the neuromuscular junction and
in the excitation-contraction coupling (ECC) system. The neuromuscular junction
is where the motor neuron connects to the muscle. Excessive buildup of potassium
ions (K+), which are normally required to transmit the nerve impulse from the
neuron to the muscle, can cause a limited form of damage to the neuromuscular
junction, inhibiting the transmission of impulses (4, 6, 7, 13, 22, 23).
Intracellular K+ build-up occurs as a result of disruption to the muscle's
membrane during mechanical action, as well as during high-frequency neural
firing, in a sort of feedback mechanism.
Past the neuromuscular junction, the ECC is formed by T-tubules that run deep
inside the muscle, conducting the impulse and causing the release of calcium
ions (Ca++) that cause the muscle to contract. Further research shows that when
too much Ca++ is released inside the muscle, also as a result of high-intensity
impulses, the ECC can become damaged and less responsive to nerve impulses (5,
13, 16, 32). Not only do you chew up your brain, but you're grinding your nerves
themselves into proverbial hamburger meat.
That's a lot of bad news. Fortunately it has some good karma to balance it out.
As noted by Dr. Zatsiorsky, there are three main ways to increase muscular
tension (33). The two that are relevant here are the maximal-effort method and
repeated-effort method. Maximal effort involves working with limit or near-limit
loads, while repeated effort entails lifting a non-maximal load to muscular
failure.
It's pretty widely known that training with maximal weights causes extensive
neural adaptation, resulting in almost immediate strength gains. This can also
occur when the repeated-effort method is used. According to Zatsiorsky, the
final 'failure rep' causes strength gains as well, due to recruitment and
fatigue of higher-threshold MU's, and a wider array of total MU's, through the
processes described above (28, 33). So taking your sets to the limit is a good
way to increase muscular strength as well as targeting a wide range of muscle
fibers. As you could imagine, this is beneficial for folks interested in either
strength or muscular size.
Not only that, but the neuron itself adapts to the stresses. It's been shown
that motor neurons exposed to high-frequency impulses end up with more developed
neuromuscular junctions, apparently capable of handling high-intensity impulses
better than those not exposed to similar stress (4, 6, 7). This is not unlike
the way a muscle grows in response to the damage inflicted upon it. These
adaptations to the junction seem to be fairly permanent (4,9).
Finally, all this metabolic and neural damage may well lead to additional
hypertrophy via biochemical signaling. There's been some recent work showing
that a variety of satellite cells that tend to cluster around the NMJ, and K+
concentrations set off a biochemical cascade that may serve to activate them
(34). There's a whole mess of processes inside the fibers themselves that can be
activated by the myriad chemical signals that result from both metabolic fatigue
and eccentric trauma, and even the activity of nerve impulses themselves, so
there's definitely a case to be made for taking things to the limit.
Learn From Your Failures
By now it's pretty obvious that training to failure is a good thing, but it
definitely has its drawbacks. The solution is pretty simple. You wouldn't train
for a true 1RM every single workout; why would you do it for a 6RM or a 10RM?
That isn't to say that training to a rep-maximum weekly won't work. It'll work
exceedingly well over short periods of time, and even over longer periods if
you're willing to sacrifice the frequency of your workouts. It won't last
forever though, so you'll do better finding a happy medium.
In one sense, HIT has things dead-on: If you're training to your best, you won't
be able to train regularly. This couldn't be truer. The caveat is you don't have
to take it to the max every time in order to see results. The max workouts
should be infrequent yes, but that does not mean they have to be your only
workouts.
In reality I'm not sure how much the minute details matter, if at all. Meaning,
if you're in the middle of a set and you think you might have one rep left, you
haven't necessarily cut yourself short by racking the bar. It also doesn't mean
that the guy that goes ahead and takes that last rep, and either has to fight it
to the top, cheat, or get a spotter to help is going to be better off either.
I'm convinced that factors like that, if they even matter at all, will only
contribute to a tiny difference that would only be noticeable over years of
training if ever.
There's no clear-cut method for figuring out what is and isn't fatiguing you
centrally. The rule of thumb I like to use is based around your 'psych' level.
If you're casually exerting yourself, then there's likely not much going on. If
you're having to concentrate and focus to complete the set, you're getting some
stress, but nothing major. This is ideally where you'd want to fall for most of
your workouts.
The final level would be when you're going all out. Metallica (classic Metallica,
not this St. Anger heresy) is blaring in your ear, you've head-butted the power
rack three or for times, and you might have even taken a nice dose of
stimulants. You've pushed it to the limit, and the set requires mental
preparation before, as well as intense focus and drive during. This is when
you've really pushed it into that zone of CNS fatigue.
By this point, it should be obvious that things have mushroomed beyond the
simple matter of going to failure versus not going to failure. Muscular failure
is really nothing more than a symptom of multiple underlying causes, mostly
neurological. It is these causes which are relevant to the bodybuilder; limiting
one's self to the nervous system's schedule is not conducive to maximizing
hypertrophy gains.
So Why the Argument?
Why does HIT and its idea of reaching absolute failure garner all the negative
attention? It isn't due to the fact that they train differently than most. It's
the fact that in general, the HIT Jedi are more than willing to fire up their
lightsabers and hack off the limbs of anyone that disagrees. Like a Jehovah's
Witness on Saturday afternoon, they want to go to everybody else's house and
tell them why they're wrong.
As a system of bodybuilding, HIT will work fine for most people. In fact, I'd go
as far as to say that in some of its incarnations it'd be ideal for a lot of
people. It's based on the concepts of recovery, hard work, and progressive
overload, and while it does lack (okay, outright reject) any system of long-term
planning, it will nevertheless produce results. There's also the fact that many
positive effects can come from training to failure, as noted. Whether those
results are better, worse, or the same as other bodybuilding systems is
unimportant to this article, and likely not worth worrying about.
What does matter is that the proponents of going to the max each and every time
don't leave it at bodybuilding. They routinely and regularly espouse their
methodology as the only one that is appropriate for any type of strength
training, including athletics. Now, even based on the fairly simple information
laid out above, it should be fairly obvious why this isn't the case.
It gets even better than that though. Most athletes in competitive sports don't
just need strength. They also require the ability to express that strength
quickly, which is a whole different matter. Simply performing straight sets to
concentric failure doesn't account for this. Training to express force quickly
requires sub-maximal weights that are moved with the intention of developing
maximal speed with rest periods long enough to minimize fatigue, not maximize it
as bodybuilders would want (28, 33). This, obviously, is fundamentally at odds
with a belief system that requires concentric failure to occur in order to
elicit any type of gain in strength or structure.
Not all athletes need to add muscle mass. For performance-oriented athletes, in
every sport from baseball to hockey to football, sheer mass is only part of the
issue. Adding mass can actually be a bad thing for some of these guys. The same
goes for general strength. It isn't always the concern, and a lot of athletes
especially at the elite level would have their time better spent on other
factors. The negative issues of training so infrequently and so stressfully will
almost always have an impact on athletes, where neural adaptation is the rule.
Note that this does not mean that lifting a weight to failure is useless. For
improving general strength levels and for improving muscle mass, it works
tremendously well. This information only argues that HIT-type work must be used
judiciously in the training of an athlete that has other concerns beyond simple
gains in muscular size.
How to Get Around It: Cybernetic Periodization and Autoregulatory Training
Putting this information into practice, the approach can be as simple as doing
most of your workouts in the 'mild' zone and using every third or fourth workout
as an all-out psyched-up max day. My personal favorite is working up to that
all-out day over a three week cycle with the fourth week used for unloading and
recovery.
In Super training, Mel Siff discusses the idea of cybernetic periodization. This
is when the athlete's own feedback is used to manipulate the training plan. The
athlete judges his overall readiness by the Rating of Perceived Exertion (RPE),
which is simply a scale of 1-10 (or 1-5 if you prefer) with 1 being least taxing
and 10 being most.
The RPE scale would correlate to the arousal states mentioned previously.
Low-effort, completely non-taxing work would fall in the 1-3 range, moderate
effort would be in the 4-6 range, and heavy work would be from 7-10. This
provides a convenient tool for longer-term planning. Using my preferred style,
the workouts would turn out as follows:
Week 1 5-6
Week 2 6-8
Week 3 8-10
Week 4 < 4
Before discussing how to put this into practice, another topic needs to be
introduced. Autoregulatory training is a concept related to cybernetic
periodization, but used for planning the individual workout as opposed to the
more general recommendations of RPE.
Using an autoregulating plan, the RPE would be used as a guideline from which
the volume and intensity is then derived. During the mild weeks, exertion would
be kept high, but not maximal. An example would be doing sets of a specific rep
range with a given weight until it becomes taxing to do so, never truly hitting
muscular failure. The heavier weeks would peak the exertion level, doing sets
leading up to a true rep maximum. The unloading week would take around 60% of
the rep maximum achieved and perform only a few sets with that weight.
This of course is only a very general example, as there are gradations of effort
and specific training methods that can be implemented accordingly. Westside's
maximal-effort days and the Bulgarian weightlifting teams' daily maximum are
both examples. Even those techniques, and others, can be affected by the overall
program design. However, given the scope of this article, this example is fine
for conveying the basic idea.
How to Fail in Your Favor
I hope this piece managed to shed some light on the issue of failure. If you're
a bodybuilder, I don't think it really matters too much if you train with a few
really heavy sets and give it all you got, or a few slightly lighter sets that
allow you to accumulate fatigue. As long as you're lifting and getting stronger,
as well as meeting your nutritional requirements, I'm really not convinced it
makes that much of a difference.
You'll just as likely be better off alternating between the two approaches, as I
noted above. There are many, many programs that do just that, including the one
I outlined; you could use one of those to great success, or you could simply
apply the concept to your existing workout. If you're an athlete that uses
strength training as just one facet of a larger program, you'll definitely want
to periodize and only utilize general strength training in the appropriate
phases when it will be most useful.
As far as supplementation, there's a variety of nootropic compounds out there
that are becoming more and more popular. Caffeine, ephedrine, and similar
compounds are helpful as they both work to increase arousal and focus via
norepinephrine, but I don't believe they'll do much for restorative purposes.
The amino acid L-tyrosine is a precursor to norepinephine, and in doses of 1-5g
it can provide a stimulatory effect. Compounds like piracetam, vinpocetine and
DMAE, the true nootropics, are making themselves known as cognition-enhancers,
and can only help with focus and drive, as well as with recovery. Dopamine
agonists can aid in neural drive as well, due to their mild stimulatory effects.
Finally, while I don't have a reference for this, I would go out on a limb and
say that creatine would also be something worth considering, due to its ability
to enhance cellular energetics. It already shows the ability to attenuate brain
damage during hypoxia; my hunch is that it will provide benefits here as well.
In closing, we have to remember that training is a complicated dance of stimuli
and response. Our goal is to understand how to manipulate the stimuli in order
to evoke the responses we desire. The information provided above should not be
expressed as any singular key to success, but rather incorporated as what it
is'another tool to help you on your way to controlling your body's destiny. As
diet and supplementation are used to manipulate the body's hormonal systems,
training can be structured to elicit similar effects. The ability to orchestrate
the stress and recovery of the body's systems is a critical and ultimately
defining capacity for any athlete.
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