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Categories of Weight Training: Part 2

thebrick

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Oct 28, 2012
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Categories of Weight Training: Part 2
By Lyle McDonald


Last week in Categories of Weight Training Part 1, I made a quick introduction to the series and talked about metabolic/depletion type training. I won’t sum any of it up here, just click the link. In that article, I also listed the three primary types of training I wanted to talk about and listed the second type as ‘hypertrophy training’.

Today, in an effort to confuse everyone including myself, I’m going to re-categorize that one initially as ‘growth training’, then babble about a bunch of underlying physiology and then go right back to calling it hypertrophy training. This is why I should plan out article series ahead of time instead of writing them on the fly. In any case….


Goals of Growth Training

Of course, the explicit goal of this type of training is building bigger muscles although there may be a variety of reasons most wish to achieve this goal. One would be to provide a base for increased strength or power performance since larger muscles are potentially stronger muscle. Athletes, depending on the specifics of their sport, might wish to actively increase muscle mass to increase their potential performance capacities.

Arguably the biggest goal of this type of training is simply aesthetics. Whether the goal is explicitly bodybuilding or one of the other physique sports (fitness or figure), looking good naked, or what have you, it’s arguably true that most seek out increased muscle size out of some sort of aesthetic type of goal. In recent years, there has been quite some interest in muscle loss with aging and methods that help older people to maintain or build new muscle mass may go a long way towards preventing health problems and falls in later life.

But before I get into the details, now would be a good time to cover the different ‘types’ of growth that can occur.


Two Types of Muscle Growth: Hypertrophy vs. Hyperplasia

This is the section that will hopefully make you understand why I went through the verbal gymnastics up above in redefining the title of this section of the series. This is also a section that didn’t appear in the original version of this article.

Basically, increases in muscle mass can potentially occur through one of two primary mechanisms which are

Hypertrophy
Hyperplasia


Hypertrophy refers to an overall increase in the actual size of the skeletal muscle mass. I’ll spare you the details, simply accept that the actual existing muscle cells grow larger. In contrast, hyperplasia refers to a situation where there is an actual increase in the number of muscle cells (or fibers) that exist. That is, rather than the existing cells/fibers growing larger, the body actually makes new ones (that presumably have potential growth).

If this is unclear, an easier example might be that of increases in body fat which can also occur through either hypertrophy (existing fat cells grow larger) or hyperplasia (the body makes new fat cells which can then fill up with fat).

Now, the topic of skeletal muscle mass hyperplasia has been one of great debate for absolute years. Some early animal research, some of which was similar to weight training (e.g. in one study they trained a cat to paw against a lever to get food) and some of which wasn’t (bird models where the wing was placed on stretch for 30 straight days), suggested that hyperplasia could and did in fact occur.

I’d note that determining this with any degree of accuracy is exceedingly tedious; you basically have to kill the animal, dissect it and then count the number of muscle fibers individually and compare the trained muscle to the untrained muscle. There is a built-in assumption that the animal had the same number of fibers in both sides to begin with and on and on it goes; obviously you can’t readily do this in humans.

But it’s been a massive area of debate as to whether or not hyperplasia actually occurs in humans. Up until recently almost no data suggested that this occurred; one or two odd recent studies (which if I recall had the added confound of steroid use) suggest that hyperplasia may actually occur in humans.

At this point in the game, whether or not hyperplasia occurs is still up to debate in my mind. What really isn’t up to debate in my mind is this:

Hyperplasia is unlikely to contribute in a major fashion to overall growth
If it occurs, it’s going to occur of it’s own accord and you probably can’t do much to control it


That is, even if hyperplasia occurs, it would appear to be of fairly minimal significance in the overall growth response. Which is why I’m now going to go back to referring simply to hypertrophy for the rest of this article. Confused yet? Me too.


Types of Hypertrophy: Myofibrillar vs. Sarcoplasmic

Moving only to hypertrophy from here on out, the next issue I want to discuss is one that is another area of some debate. Very simplistically speaking, you can think of muscle mass as being made up of the actual skeletal muscle myofibrils (basically the fibers that actually generate force) and ‘everything else’ including water, glycogen, minerals, connective tissues, etc. This latter part of muscle, or at least part of it, is often referred to as the sarcoplasm.

For years, a distinction between myofibrillar growth (growth of the actual contractile fibers) and sarcoplasmic growth (increases in storage of glycogen, water, etc.) which doesn’t really contribute to overall performance (but still makes you look bigger). Some also refer to this as functional hypertrophy vs. non-functional hypertrophy.

In this schema, performance oriented athletes generally want to focus on functional hypertrophy; that is, actual increases in the size of the myofibrils. Because simply bigger (without performing any better) is of little use to them. In contrast, for athletes, focusing on sarcoplasmic growth isn’t usually of much relevance; it might make them look bigger but won’t make them perform any better since glycogen and water don’t generate force. Of course, both types of growth contribute to overall size so for physique oriented athletes, especially bodybuilders, some element of focus on both may be relevant to maximize overall muscular size.

It’s still somewhat debatable how much the above concepts really exist or apply in the real world. Some research in the early 80’s suggested that this separation exists (but those results may have been colored by steroid use as well) and European sources such as Supertraining by Mel Siff and Yuri Verkoshansky as well as Science and Practice of Strength Training by Vladimir Zatsiorsky speak of the concepts as if they are proven. Other folks, such as Bryan Haycock, who’s opinion I think highly of, think the distinction is a load of crap.

Personally, I tend to think that there’s some merit to it and I’ll leave it at that. There do appear to be some visual differences between athletes who train heavily and those who just pump up all day. As well, some have found that pump type trainers tend to shrink more quickly (suggesting that the growth is of a more transient type) than those that train heavily. Or I’m just hallucinating again.

Finishing up that concept, I’d note that, assuming the above distinction does exist, no type of training will only build one or the other. Clearly bodybuilders who do nothing but pump all day build some real muscle tissue (in this vein a recent study showed that training at even a low 30% of 1 repetition maximum stimulated protein synthesis), guys who do lots of heavier work build some sarcoplasmic volume.

It’s simply that different types of training may build one or the other somewhat preferentially. Again, keep in mind that all training is on a continuum, you can’t readily say ‘this is one type of training’ and ‘this is another’. Rather, it’s just a continuum of adaptations as you move through the different loading parameters.


What Stimulates Hypertrophy?

Years ago I asked a smart-assed supervisor of mine ‘What makes muscle grow?’ and he replied ‘Sunlight and lots of water.’ Ah, if it were only that easy. Debates (both scientific and empirical) over the actual stimulus for muscle growth have raged on for decades now with some simply asserting ‘We have no idea what stimulates growth.’ This latter statement might have been correct a few years ago but at this point research continues to uncover both the acute training and molecular regulators of muscle growth.

And there are actually a few different factors that impact on the growth response to training. As one recent review paper put it, simply we can look at the stimulus for muscle growth as falling into three distinct (but likely overlapping) categories: progressive tension overload, muscle damage and metabolic stress. Each of which may play some sort of role in the overall growth stimulating processes. I’ve commonly referred to growth as being related to primarily tension (load on the bar, roughly) or fatigue (metabolic issues) but damage also appears to be involved.
The mechanisms of muscle hypertrophy and their app... [J Strength Cond Res. 2010] - PubMed result

Progressive tension overload is arguably the one that I tend to put the most focus on since I tend to be of the opinion that it’s the key stimulus for growth (other factors being secondary); as a generality, once you take anabolic steroids out of the picture, the muscularly largest athletes tend to be the strongest as well. Perhaps more accurately, athletes who make the best strength gains in a moderate repetition range combined with sufficient food tend to grow the best.

This means that, over time, weight needs to be added to the bar to continue stimulating growth. How often, how much, etc. is a topic for another day. It’s interesting to note that the idea that mechanical work was the key stimulus for growth isn’t even a new one, back in the 70’s a classic paper by Goldspink argued for that very thing.
Mechanism of work-induced hypertrophy of skeletal ... [Med Sci Sports. 1975] - PubMed result

The idea that muscle damage plays a role in growth has been around for years with a variety of different effects being offered. It’s also arguably been why a focus on being sore from training is often sought (soreness often resulting from the same type of heavy work that may cause damage and growth). Addressing that in detail would also take another article. Sufficed to say that, outside of untrained folks, muscle damage tends to occur most readily in response to the eccentric (lowering) part of weight training. In this vein, many studies have shown that a combination of concentric + eccentric work generates better growth than pure concentric work.

Finally there is the issue of metabolic stress and/or fatigue with various local metabolite (e.g. Calcium) accumulation possibly being related to the growth stimulus. And there may be others; for example hypoxia (a lack of sufficient oxygen) has often been argued as part of the growth stimulus and bodybuilders have used various types of continuous tension non-lock training to try to achieve this. And the odd occlusion studies out of Japan (where low intensity training plus actual occlusion of blood flow) seem to back that up; of course the rapid rate of gain and loss of lean body mass in those studies also suggest that it may just be glycogen and water.

Ultimately, the three stimuli discussed above, tension overload, damage and metabolic stress (fatigue) seem to be the primary factors at this point. And I think if you look at most successful training programs, they tend to have some combination of all three of these.

And as molecular studies continue to determine more of the actual mechanistic stimuli for hypertrophy (it’s a letter jumble including things like mTOR, AKT and others), it may turn out that each of the different stimuli tends to preferentially activate different pathways or that optimal results are had with a combination of each stimuli.

I’d mention here that one aspect of growth that I didn’t talk about was the acute hormonal response to training. While much has been made of this over the years, recent research, as I outlined in Casein Hydrolysate and Anabolic Hormones and Growth – Research Review, suggest that they have little impact on the overall growth response.
Casein Hydrolysate and Anabolic Hormones and Growth - Research Review | BodyRecomposition - The Home of Lyle McDonald

And that’s where I’m going to end it today since it’s already running long. In Part 3, I’ll continue with the topic of hypertrophy training and look at things like loading parameters (intensity, frequency, volumes), exercise selection and other stuff just as I did in Categories of Weight Training Part 1 for metabolic/depletion work.