The concept of 'working hard' originally came to prominence, in a bad way, in the 1970s under Arthur Jones,
Ellington Darden, and Mike Mentzer, the core group behind HIT. At the time, in a bodybuilding culture based
on high volumes of endless exercise, the ideas behind HIT were somewhat out of place.
One of the core tenets of HIT is training with 'intensity'. Hence the name High Intensity Training. The HIT guys
realized that there's a trade-off between quality and quantity in a workout, which is actually not a bad
observation. Only, there's a problem. What HIT calls intensity and what the rest of us call intensity aren't the
same thing.
Worse, they've got a rather unorthodox idea of what actually stimulates muscle growth. By unorthodox, I mean
completely incorrect and not supported by any real data.
What HIT suggests is very mentally-taxing training. According to them, it's all about the effort and strain you
put into your sets. The more you have to fight and push with a lot of exertion, the better your results.
Of course the Bro-crowd has latched on to this too. 'Intensity' to your typical gym bodybuilder means loud
music, yelling, and a brow-furrowing scowl. Now, since we have other information to go on, I think this is pretty
stupid to do on a regular basis. But as always, there is a point to be taken away.
This idea of 'intensity' - which is really intensive training – focuses on the idea of perceived effort. While I don't
see any need to do this every time you set foot in the gym, there is something to be said for workouts where
you try to push past your previous limits.
Training with a high exertion is one way to do this. And this isn't complicated – it's exactly what it sounds like.
You train to a point where you have to focus and really exert yourself to complete your reps. HIT took things a
step further, though. They reached the conclusion that if hard work created results, then hard work must be
the goal in itself. If hard work is responsible for muscle size, then the harder you work, the greater your results.
Thus, in their view, intensive training goes hand in hand with the idea of reaching muscular failure.
Muscular failure is defined as the inability to complete a repetition without external assistance (such as having
a partner taking the weight from you). This can occur in different stages of the lift.
Concentric failure is inability to complete the lifting phase, while isometric failure is inability to hold the weight.
Eccentric failure, on paper at least, is inability to control the weight on the lowering phase, but as a matter of
course that doesn't occur. If you can't lower the weight under control, you're either injured or it's just too
damn heavy in the first place. The inhibition reflexes mean that you'd just as likely drop anything this heavy in
the first place.
So in practice, 'taking sets to failure' in this context means doing reps to the point where you can't complete
another rep, or can't hold the bar in place after a missing a rep. HIT calls failure your momentary muscular
ability - to them, failure is the limit of your ability to work hard. Therefore, training to failure yields the best
possible results.
For some reason the HIT proponents got it in their heads that muscle growth was an on or off thing. You either
stimulated the muscle to grow, or you didn't, and that stimulus to grow was the inroad created by working as
hard as possible. By training to complete failure, you achieved the hardest work you could achieve. Pushing to
the limit would dig in to the muscle's ability, and if you dug in hard enough, growth was triggered. Easy, simple,
to the point. Assuming even a shred of it were true.
If you didn't have any research to tell you otherwise, I could understand the reasoning behind this thought
process. If you're just going by logical extrapolation, which is what Mentzer prided himself on, it's not an
unreasonable conclusion in itself.
However, pretty much all of those assumptions and leaps of logic are questionable, even without more recent
research. The knowledge gained in the past few decades has pretty much put the last nails in that coffin.
First, the assumption that muscle growth either happens or it doesn't. This is directly at odds with the dose-
response relationship that has been established between exercise and muscle growth. There's no on/off
switch, it's a matter of degrees.
Second, you have to assume that a handful of sets, potentially as few as one, would be enough to sufficiently
recruit and train a good portion of the motor units in a muscle. Research supports a dose-response
relationship. One set will have an effect, but more sets will create a greater total effect.
Finally, you have to assume that going to failure stresses the muscle in a way that's superior to other
approaches. That one hasn't held up, either.
Unfortunately for the simplistic HIT ideas, we've learned a great deal since the 1970s. If you've read anything
I've written on the growth process and the nervous system so far, you'll know right off the bat why the basic
premises are flawed.
The growth response is not signaled with a simple on/off switch, and muscular failure doesn't have much to do
with growth signaling to begin with. Failure has a lot more to do with wearing out certain components of the
nervous system than it does with the actual muscle fibers. Further, one set is not likely to bring about the best
growth due to the dose-response relationship between exercise and gains.
If anything, it's some blend of weight, volume, and fatigue, to create tension-time overload, that triggers
growth. HITs central premise has been proven incorrect.
To look into the topic a little deeper, consider what failure means: you've lost the ability to move the weight.
Why does this happen?
It ties back into the motor recruitment stuff. The higher the intensity (as weight on the bar), the shorter the
time that intensity can be maintained. The motor units with the highest force potential tend to tire out the
quickest.
We're mainly discussing the 'strength zone' here, where failure occurs because of neurological and muscular
factors. This is going to vary, of course, but as a rule this will limit you to somewhere around 12-20 reps in a
single set. Sets longer than this starts to shift over into strength endurance, where metabolic effects can cause
you to fail or stop a set due to pain.
With maximal weights, above 85% of the maximal voluntary contraction give or take, the movement is
dominantly neurological. There will have be little relative impact on the actual muscle; it simply isn't active long
enough to experience a lot of stress.
Failure at this point results from neurological factors: your ability to recruit motor units and keep them turned
on. The high-threshold motor units, the weak links in the chain, will fatigue very quickly under those conditions.
Sometimes, you just won't have the ability to keep neural drive turned on. When either of these things happen,
you fail.
Once you go a little further down the intensity ladder, this changes a bit. The sets last longer – you might get
anywhere from 4-10 reps, and failing will involve more of the muscle tissue.
Actual disruption of the myofibrils and fiber membrane starts to occur at this stage. As the set progresses,
more and more motor units start to fatigue. As I've said several times already, fatigue sets in and the set starts
to grind.
Now what happens here is interesting. We've seen that high levels of arousal or psych-up can influence this.
The more focused and worked up you are, the more you can grind through the fatigue. This is where the
'intensity' or perceived effort comes into the equation. You're literally pushing yourself through the fatigue.
When you work to failure, or even just grind through fatigue during the course of a set, you're tiring out those
motor units and then causing disruption of the actual muscle fibers with further reps.
This is probably where the mystical beliefs around 'intensity' and training to failure come into the equation.
Training to a rep-maximum with moderate reps (4-10 or so) will do a number on the muscle, and train (not just
recruit) both a wider range of motor units and their actual fibers. Research has shown for quite some time that
training in this manner is at least efficient for developing strength, given equal amounts of work (Atha 1981,
Zatsiorsky 1995, Lawton et al. 2004, Drinkwater et al. 2007).
In fact, the study performed by Lawton et al. (2004) really illustrates this in effect.
The study compared the effects of training with a fixed intensity between two groups over six weeks. One
group (CR) used continuous repetitions done for four sets of six reps. The other group (ISR) used intra-set rests,
performing 8 sets of 3 reps. Both groups were controlled for intensity, total number of reps, and total time to
completion of the exercise. The only difference was that the CR group completed the sets normally, without
resting, while the ISR group took a 30 second rest interval in the middle of the set.
In other words, if they were using a 6RM weight, the CR group did six reps. The ISR group did three reps, rested
for 30 seconds, then did the remaining three reps. That way, the volume was controlled – the only difference
was that short rest within the set.
After six weeks, it was found that the CR group had significantly improved bench press strength, as tested by
the 6RM, compared to ISR group. Neither group showed an advantage in tested power output.
It was found that the concentric time under tension (TUT) was significantly higher for the CR group, and this
was thought to be due to the fatigue accumulated during their sets. The ISR group didn't develop fatigue since
they were given rests, and thus they experienced a shorter TUT since they didn't slow down.
At first glance this might lead you to believe that higher TUT alone yielded the gains, giving support for training
to fatigue. But that would be jumping the gun a bit; there's other conclusions we can draw from this.
The advantage in the CR group is obvious. They created more fatigue, and thus for the given volume and
intensity, they worked harder.
It's not the higher TUT in itself that caused this – the TUT is just describing how the reps slowed down as
fatigue set in. The higher TUT is showing that the CR group worked harder given an identical intensity and
volume.
There's one obvious conclusion to be drawn: for any given amount of volume, intensive training will get the job
done most efficiently. I'm not sure that's ever been in question, at least where pure size or strength is the goal.
But what about the intra-set rest group? For our purposes, this group will be the 'dynamic effort' or speed-
training group. They generate less fatigue, with the trade-off being higher-quality reps.
With just a glance it seems inferior, based on the results of this study. The ISR group had no advantage in
power output, and it didn't even improve strength as well as the other group.
However, I'm not so quick to write it off. The main benefit to dynamic-type training is not economy. The
advantage is that it lets you either use heavier weights, do more total volume, or both, without fatigue wearing
you out.
Intensive training will give you the greatest effect for a small volume of work. The drawback is that the fatigue
you create on each set will limit the amount of work you can do.
The take home to me is not that intensive training is better – it's that intensive training is better for small
volumes of work. If you choose to use dynamic-type training, the trick is to create stress by either doing more
volume (instead of 24 reps like the example, do 36) or using heavier weights (instead of 6RM weights, use 4RM
weights).
In my mind, the protocol that has you working the hardest will translate into the greatest effect. With small
volumes, work until fatigue sets in and your reps slow down. If you're using non-fatiguing sets, then do more of
them and use heavier weights.
What you'll tend to find is that 'working hard' makes you better at RM attempts, since the body adapts
specifically to the type of training (big shocker). This is a good thing, obviously. There's drawbacks, too.
The thing is, though, it seems that the grinding is what is important, not the actual act of reaching failure.
Those last hard reps are creating the effect, and there's just nothing magical about the point where you lose
the ability to move the weight.
Intensive training, which is lifting to failure, forced reps, and any other kinds of high-fatigue lifting, has been
shown to require longer recovery times than non-failure training, along with causing significant negative
changes in hormonal state (Raastad et al. 2000, Ahtianen et al. 2003, 2004, Izquierdo et al. 2006). There's also
some changes in muscle function that are more severe with high-stress training (Raastad and Hallen 2000,
Raastad et al. 2001).
There just doesn't seem to be a lot of difference between training to a point near failure and training to a point
where you can't move the weight on your own. HIT is convinced that the point of failure is the magic threshold
– but there's nothing to support that. Certainly nothing convincing enough to deal with the hit to recovery
time.
It doesn't seem to be reaching actual failure that's important, but those slow and grinding reps that lead up to
it. If that's the case, then it means anything that has you operating under conditions of fatigue could have
similar effects.
This isn't really surprising, either. The harder you work and the more fatigue you create in the body, the greater
the shock to the system. The down side is that if intensive or failure-based training is used frequently, you
could be impairing your recovery.
The stuff you'll be recovering from is mostly damage to the cell membrane and other connective tissues.
There's also some disruption to the structures that conduct nerve impulses, due to high levels of calcium that
build up during fatiguing exercise. These issues have little to no impact on protein synthesis rates, although
there's reason to believe that some inflammation will do good things for the satellite cells. Remember also that
too much damage can also be counterproductive to growth.
You have to take into account the psychological effects of failure as well. It can be hard to psych up for workout
after workout, knowing that you have to go in and effectively try to break yourself. Since arousal, neural drive,
and your overall well-being are closely tied together, it wouldn't surprise me a bit to see some very real
negative consequences from hammering yourself like this on a consistent basis.
A hard workout will have positive effects, but it's balanced out by some pretty hefty negatives. If you train like
that each and every time, you won't be able to train with the frequency you need. HIT says you need to train
less often; I think the case is made for harder and lighter workouts.
However, you do have to keep some perspective too. It's easy to get wrapped up in these little details, like they
dominate the whole workout, but in practice you can apply things like this in different ways. Taking a set of
dumbbell curls or calf raises to failure isn't quite the same thing as a set of squats or bench press, either
mentally or physically. Smaller muscle groups and exercises that don't require a lot of focus (meaning, isolation
work) aren't going cause the same negative impact.
Failure or not aside, I think the more important point is that you need to have some degree of exertion in your
workouts; otherwise you're just going through the motions.
I'd also like to point out the difference in training to a rep-maximum – which is where you complete all your
reps, but couldn't do another – and training to failure, which is where you don't complete the rep because you
literally can't. These are two different animals.
The studies that have been done comparing training to failure or beyond vs. staying shy of it have shown no
real difference in outcome (Izquierdo et al. 2006, Drinkwater et al. 2007). If anything the advantage is given to
non-failure training, which seems to create equal (if not better) strength gains while limiting the fatigue in a
session and the recovery time between sessions. You're still taxing the muscle, but you're avoiding some of the
negative neural stuff.
So there's that to consider also. Of course on the other side of this argument, we get the assertion from some
that 'training to failure is training to fail'. I think that's a bit hasty when you don't consider your target
audience. Yes, training to failure can impact recovery, and if used carelessly it can impair power output –
something critical for many athletes.
That statement has largely been used to discredit the use of bodybuilding, and HIT specifically, in training
athletes for sports. From that viewpoint, it's pretty well dead-on. Just remember the context. For bodybuilders
and strength-focused athletes, I'm not sure I see the issue.
In as much as this affects recovery, you should certainly be mindful when you have any kind of hard workouts.
But there's plenty of evidence showing that intensive training is actually good for maximal strength – the
heavy, slow type of lifting that powerlifters and bodybuilders would be concerned with.
I'm really not for or against, as you can see. I think reducing it to a black and white argument is a bit naïve.
There's some instances where going to failure and otherwise pushing the limit will be useful; in other
situations, it's not a good idea.
A 2007 review paper by Willardson backs up this viewpoint, discussing the idea of training to failure as a means
of breaking plateaus in more advanced lifters. Going to failure has advantages due to motor unit voodoo and
the higher stress involved, but if you use do it often for long periods of time, you increase the possibility of
overreaching yourself.
The HIT guys and other failure advocates are going to fire back. Usually their argument will be something about
how you can't know you're working hard unless you work to the limit. Of course, that's nonsense to anyone
that's ever actually lifted a weight. You can tell when a set starts to get hard, when you start to slow down and
really have to focus on pushing and grinding. As it turns out, there's a pretty easy and reliable way of recording
how difficult your sets are, which I'll touch on later.
To me, the real goal here is to reach a point where you have to strain and grind. As long as you're doing that, it
doesn't matter if you actually hit the point failure or not. There's nothing particularly special about it, other
than the degree of stress it causes.
