A heavy duty is ahead of us! Tackling some of the most controversial and disputed ideas and practices in bodybuilding, all embodied in an equally polemical workout system: Mike Mentzer’s Heavy Duty.
A Heavy Duty Indeed
The proponents of this set of workout principles are equally ardent in defending it, as are its adversaries in calling it “rantings of a lunatic” (The Poliquin Principles). We’ll try to examine where the truth lies, entering the never-ending debates on necessity of training to failure, the one-vs-many set debate, and the value of anecdotal evidence in the bodybuilding world. Stay tuned for both parts of the article!
HIT (High Intensity Training) is a class of training routines that bear several common marks, most important of which are usage of extremely low volume, both per session and during training microcycle, and extensive reliance on using so-called “shock techniques” in order to facilitate faster muscular growth. HIT routines are bodybuilding routines; all their instances are primarily hypertrophy-oriented.
First popular example of an HIT routine was Mike Mentzer’s Heavy Duty (HD). The basic principles behind it weren’t his invention, but that of Arthur Jones (and he most likely got it from someone else, but that’s another matter altogether), who “tested” these principles in the (in)famous Colorado Experiment, which we’ll mention in more detail in Part II. However, Mentzer first popularized these principles in a manner that we find consistent with usual definition of “training programs” (Jones’ application of that same principles was more a matter of marketing strategy than actually creating a training system for bodybuilders to use). His Heavy Duty training is the most extreme example of a popular HIT routine – of course there are lunatics who take even that a few notches further, but these are isolated cases, and, generally speaking, majority of common HIT routines are milder than Heavy Duty, mainly because they don’t hammer away with shock techniques, but occasionally also because they stray away from the golden rule of “only 1 working set per exercise.”
The Principles Of HIT And HD
This article isn’t so much about a particular program, but speaks more of the principles that comprise it. What makes them special is that nearly all of them are related to some of the most controversial topics in bodybuilding world – training to failure, one set vs. multiple sets, and how much rest does one really need. I only use HD as an example because it’s basically the only routine that includes all those ideas in their purest form. Therefore, this article isn’t about Dorian Yates’ version of Heavy Duty, or routines by Clarence Bass, primarily because they tend to usher a lot more volume by both doing multiple sets (up to 2) and/or, more importantly, doing several similar exercises (which again translates to more overall volume per bodypart).
In my opinion, the main reason why HIT, and HD in particular, fails to be a great workout system is that the roots of all the reasoning behind it are predominantly philosophical in nature. They are good as concepts – examples include the idea that quality of a workout trumps quantity, the important role of effort in training, as well as the notion that that we don’t grow in the gym, but outside it, while resting. The problem, however, is that HD puts these ideas into practice in a wrong way. A part of the blame rests on the fact that it grew in opposition to the prevailing training concepts of the time, which included overwhelmingly voluminous routines requiring hours of training time nearly every day of the week, so HD went to the other extreme, focusing on only one working set and highly infrequent workouts. On the other hand, some other implementations of the said principles, such as the one stating that you have to hit momentary muscular failure to promote hypertrophy, are plainly wrong, but we’ll get to all of that in passages to come.
What Are Shock Techniques?
Shock techniques include several different ways of performing your sets, all for the purpose of stimulating muscle into new growth by providing a different kind of stimulus. Please note everything that’s embedded into this definition, namely the word “sets” – a set is comprised of reps, therefore varying sets implies varying the way you perform your reps; also, there a shock technique can include multiple sets stringer together in a particular manner. Examples include forced negatives, drop sets, super-/tri-/giant-sets, pre-/post- exhaustion, rest-pausing, extended sets, as well as using static reps at any point of ROM.
There is a number of reasons why we don’t use shock techniques on a regular basis, and all of them illustrate the redundancy of implementing them in one’s training to such a degree as it is customary in HD-HIT routines. Examining these arguments will also give us a chance to dismiss some fundamental HIT ideas as false, or at least falsely or limitedly perceived.
A basic example of a misapplied shock technique is the so-called pre-exhaustion. I’m using this example as it’s the most commonly used shock technique in HIT, especially in HD. The idea is basically to precede a compound exercise with an isolation one targeting the main mover of the compound (the two are usually supersetted, meaning you do the isolation set, and then, without any rest, proceed onto the compound set). By doing so, you avoid the issue of compound exercise being limited by its weakest link, which (at least if pre-exhaustion proponents are asked) is almost never the main mover, but a synergist or a stabilizer muscle, so the main mover ends up being underworked and understimulated. However, by doing the isolation beforehand, you tire the main mover out, so it hits failure at the same time as the weak link. Another aspect of that principle would be forcing you to use less weight on the compound (because it’s already fatigued), which would allow for more work on it since it’d be easier on the weak link. Good idea, right? Wrong.
Any exercise that is a staple of your routine should regularly be done maximally. That’s a fairly limited statement, but I’m putting things that way to make a sharp distinction from HD’s regular usage of sub-maximal weights that result from pre-exhaustion (a funny note – pre-exhaustion method actually forces you to reduce intensity on your exercises; yet it’s a staple training method of system named High Intensity training). The fact that this reduces the effectiveness of the compound as the element of inducing major stress on your body is pretty obvious, and, to most lifters, this will be enough evidence for this part of the pre-exhaustion critique.
However, there are some trainees that have a bodybuilding one-track-mind, and actually think it’s better if an exercise, no matter its magnitude, targets as few muscles as possible. Therefore, they like their bench press to target their chest, squats to be a quad exercise, and god forbid some arm flexor involvement on rows. These people also tend to value muscular size as their only serious training goal. So, here’s how pre-exhaustion can actually make you smaller in the long run. (Note – what follows is a very simplified model of motor unit recruitment. On a wider scale, things aren’t so straight-forward, but for most HIT routines, and HD in particular, it forms an accurate objection. Please remember that this is just a hypothesis – I don’t know of any clinical studies that dealt with this question.)
There is something in exercise physiology called Henneman’s Size Principle. It basically states that motor units are generally recruited in order of smallest to largest (there are exceptions to this rule, but they’re rare and outside the scope of this article). Another way of putting that is saying that the need for a stronger muscle contraction is (again, generally) the only way to recruit largest motor units. So far so good? Now, the trick is that large(r) fibers have much greater potential for hypertrophy than smaller ones. They’re also the ones we call fast-twitch fibers, because of their ability to generate large amounts of force for short(er) periods of time.
So what basically happens is this: you go for the pec-deck and do a set of 10 to failure. All this does is tire smaller (slow-twitch) MUs, as well as a part of larger ones (since load for 10 RM is (usually) around 75% of your 1 RM, which is sufficient intensity for effectively targeting large MUs). The load used on the pec-deck is much lesser than that of a bench press, so less overall fibers were recruited. Then you go to the compound move, the bench press. Since some of your fibers are already fatigued, you are forced to use a lesser load (which is, after all, the idea behind pre-exhaustion). However, lesser load on the bench press means less fiber recruitment, which makes you unable to target the rest of the MUs that weren’t recruited when you did the pec-deck, and which would’ve been recruited had you done the bench press fresh – and this doesn’t happen just on the main muscle you’re trying to work, but in synergists as well. Less work for them means less MUs that have to do some work and subsequently grow (this includes the ones that are the most prone to hypertrophy). This is a very colorful example of a common sense idea failing hard in real training. It’s also why constant research is needed to be able to deliver best results – you can’t deduce bodybuilding on your own, but you most certainly can acquire as much data as possible and then sort them out to find out what should work, and what shouldn’t.
More Problems With Pre-Exhaustion
The argument of weak links limiting growth of the main mover rarely holds water as well. For one, the cases where failing of a synergist (or, even less, a stabilizer) steals more than one or two reps are rare with experienced trainees. Actually, the most common case here is core limiting exercises like squats, bent-over rows or overhead presses, and the only solution here is actually the opposite of what pre-exhaustion proposes – a strong core is a must in any weight training, hence the answer is to strengthen your core. This leads us to an obvious problem with pre-exhaustion, and that’s the fact that it, over time, actually increases the gap between strong and weak links in the exercise. Just think about it – you go and give all out on leg extension, then go and hit quads some more on squats, while your lower back is expected to progress with submaximal squat weights. Again, in the long run, this is a bad solution. If the discrepancy is really that great, you’re much better off doing post-exhaustion, which allows you to give all you got on the major compound, before adding some more (necessary) workload by doing an exercise that doesn’t include the weak link (note that this doesn’t necessarily have to be a compound – if your lower back fails on squats, nothing prevents you from doing some lunges afterwards to finish your legs off).
There’s also the problem of tracking progress: which exercise in the compound-isolation pair will you strive to increase, and by how much weekly? An entire paragraph could be written on possible doubts and twists this problem brings in, but this isn’t an article on shock techniques. Suffice it to say that using any shock technique on a regular basis makes adhering to the progressive overload principle in a continuous and systematic manner nearly impossible, and there lies another HIT-HD pitfall, this one being in sharp contrast to continuous progress it (nominally) advocates. This again brings us to the problem of progressing the very weak link you’re trying to eliminate – most scenarios involving progressing with pre-exhaustion on regular basis lead to strengthening the primary mover (although suboptimally, for reasons stated in the previous section), but the strength of the weak link stagnates, further deepening the gorge between it and the strong part of the chain.
Training To Failure – Yes Or No
The issues related with other shock techniques aren’t so much of interest to us. For example, the fact that eccentric-only training (due to supramaximal loads being used) is very hard on joints and connective tissues, and thus shouldn’t be used regularly is important for demonstrating the detrimental effect of consistent shock technique usage on training longevity (which I wrote about in this series).
This, however, isn’t the main issue we’re trying to deal with here. Doing shock techniques every time you hit the gym would inevitably lead to aches and inflammations, and, eventually, you’d know better than to rely so much on trying to move some more weight with a fried CNS. On the other hand, there is a bad practice that you can use your entire training career without suffering any health problems, yet it’d still impede your gains – the practice of taking every single set to the point of failure. (Just a quick note – by “impeding gains” I mean gaining less and at a slower pace than you could. Showing people who’ve been training to failure for 20+ years and still have gotten big is a lousy argument – if you don’t hit your genetic potential in 20 years (presuming that’s your ultimate training goal), then you’re really doing something wrong.)
This is a delicate topic, and, in the end, it doesn’t matter so much. The difference in gains between a regular trainee taking his sets to failure, and the one that doesn’t can, but needn’t be drastic, or even noticeable in the long run. What I’m trying to dispel here are several myths that Mike Mentzer used to promote training to failure as the best means for lifting.
First issue here is his troublesome definition of effort and intensity. Taken from Mike Mentzer’s tips:
If a person could curl a 100 pound barbell for 10 reps to failure which rep would be more productive in terms of stimulating an increase in strength and size, the first, the least intense, or the last, the most intense? Obviously it is the last.
The problem is that things don’t really work that way. The last rep (one taking you to failure) is more difficult to complete not because your muscles are working harder, but because some fibers (primarily the large, fast-twitch ones) have already been fatigued and stopped firing. So, technically, your last, “most intense” rep, actually uses less muscle than the first one. Just because it hurts more doesn’t mean it’s more intense. (I objected this unquantifiable definition of intensity in this article).
Mental effort isn’t what’s forcing your muscles to grow – repeated exposure to progressively heavier mechanical loads is. This is actually where HIT’s pre-obsession with shock techniques comes into play, because they amplify this sensation of “working hard” by putting you through slow, painful, grinding reps. The fact that fatigue alone doesn’t force your body to grow is pretty self-evident from the lack of gains you get from curling a Coke bottle to failure (and doing some rest-paused reps afterwards).
Stimulating The Muscle Properly
Next thing that strikes the eye is the following (again from the “tips” site):
Ending a set before failure, just because an arbitrary number of reps have been completed simply will not induce growth.
Again, not true. Inducing hypertrophy isn’t an on/off thing, with failure being the magical component that will flip the switch in the right direction, because there is, in fact, an established does-response relationship in regard to hypertrophy (more on this in Part II of this article). It’s true that one needs effort to grow, but this effort manifests itself in using progressively heavier loads, and reaching failure bears little importance in that matter (again, we’ll go back to this when we examine one set vs. multiple sets in Part II).
The biggest difference, however, between taking sets to failure and not doing so lies in long term practice. So no, there’s nothing magical with going to failure, but is a bad idea or training practice? Studies confirm the basic premise: taking sets to failure does allow for slightly more gains on a smaller overall workload, but at the expense of more inter- and intra-session fatigue (meaning more recovery time, which messes up training frequency), significant negative changes in hormonal state and possible psychological problems resulting from the need to drive yourself hard to extend your training beyond the point of failure every time you’re at the gym (Izquierdo et al. (2006), Drinkwater et al. (2007), Raastad et al. (2000), Ahtianen et al. (2003, 2004), Lawton et al. (2004)). I also read that “regular failed attempts lead to a reduction in a lowering of the Golgi Tendon Organ excitation threshold”, but the source for that claim is the author’s personal communication with Dr. Fred Hatfield (Dr. Squat), so I have no citations to provide regarding it.
Another issue here is that training to failure takes you through the grinding zone of the set, where exercise form begins to deteriorate. This, naturally, leads to higher risk of injury compared to training methods that keep their trainees’ sets shy of failure.
So, to conclude: taking sets to failure, at least in my opinion, has a greater potential risk than reward, especially in the long run, by forcing you to use lesser workloads (less weights with less volume), train less frequently, and making you more prone to overtraining and overreaching (both physical and mental), all with a greater chance of getting injured. And all of this in the face of Mike Mentzer’s (false) assumption that failure stimulates fibers in some unique way.
Don’t Miss Part II!
In part II we take the HIT story even further, by attacking the one set dogma, needed frequency of training, as well as the role and importance of anecdote evidence in bodybuilding theory and practice. Read it now!