Matt Metzgar

More on Variable Resistance

Here is one study that compares linear progreesion versus variable progression in strength training.  The first group sought to increase strength over 12 weeks by gradually moving to heavier loads and a lower number of repetitions.  The second group changed things every time they lifted.  The variable group showed significantly greater gains than the traditional group. 

There are plenty of other studies out there.  Here's one that compares periodized to non-periodized resistance training over 9 months in women tennis players.  The periodized program produced significantly more benefits.

Variable Resistance II

Earlier this year, I posted my ideas about variable resistance.  To summarize, I feel that the body is not designed for linear progression in weights, but instead is suited towards varying resistance within a certain range.

I still believe this is true, but now I have more reasons to do so.  As I've mentioned recently, hunter-gatherers engaged in high-intensity activity primarily for the purpose of acquiring game.  And certainly, the size of this game fluctuated over time.  For example, one day a hunter might acquire game that weighs 50 lbs, the next day 100 lbs, and the next day no game at all.  There would be seasonal variation in this as well, as the mix of available game and the weights would change.

If this is the environment under which our muscles evolved, then you can hypothesize that a properly designed resistance training program should have fluctuating resistance over time.  Of course, I am not the first to say this as ideas like periodization have been around for decades.  But this theory does provide a biological basis for why programs with varying resistance may be more successful than programs based on linear progression.

Lift More, Eat More?

I've been thinking about many implications from my theory on resistance training and protein.  One has to do with the amount of effort or intensity during exercise and the effect on protein intake.

Hunters used muscular effort in the capture of game, the butchering of game, and carrying the meat back to camp.  If a hunter was capturing large game, then the degree of muscular loading would be higher versus capturing small game.  Yet along with this greater muscular effort should come a greater quantity of meat (protein and fat).

From this, you can hypothesize that the harder you work out, the more protein and fat you should ingest after the workout.  Your body may be "expecting" it, so to speak.  Also, the combination of heavier lifting with higher protein and fat intake should help to build muscle - muscle that can be used in the next "hunt". 

Forest Environments

Here is a great paper, "The Effects of Exercise in Forest and Urban Environments on Nervous Activity of Normal Young Adults."   

The paper discusses how humans have lived in forests for millions of years, and how the recent transformation to urban living can have negative effects on health.  To test this, they had subjects perform exercise in a forest environment and also in an urban environment.  Nervous system activity was almost 20% lower after exercising in the forest environment compared to the urban environment.

This study rings true for me.  I would much, much rather exercise in a natural environment than a man-made one.

Heels

As I've mentioned before, I love flat shoes.  The idea is that we are meant to go barefoot, so therefore minimal shoes should be the best choice.

I thought a visual representation would help.  The two photos below are of the Puma H Street (my favorite) and a Reebok cross-trainer.  The difference in heel size is quite noticeable. 

It seems probable that such a large heel would alter a person's walking gait.  It would also change how pressure is distributed in the body.  You can try this for yourself by standing barefooted, and then inserting a book under you heels.  The body first leans forward, and then to compensate you have to arch your back some.

My bet is that heeled shoes can have many negative consequences, such as low back problems and knee pain.  Some recent research is starting to show this, such as this study which connects heel height to foot problems.

Unsuccessful Hunters

My last post predicted that "unsuccessful hunters" - those that are not engaging in intense activity and not acquiring enough calories - will lose fat mass as well as muscle mass, and exhibit a slower metabolism.  This study shows this to be true.

A group of men had their normal calorie intake cut by 20% for 10 weeks.  Subjects lost body weight and their metabolic rate decreased as well.  However, 17% of the body weight lost was muscle.

These "unsuccessful hunters" started a downward spiral towards less muscle mass and correspondingly a lesser ability to "acquire game."

More on Muscle as an Indicator

So far I have discussed how muscle mass can function as a positive indicator, as a sign of a successful "hunting record".  But what about the reverse, when a hunter is not successful?

The lack of sufficient calories over time causes a loss of body weight and also a decrease in resting metabolic rate.  The decrease in metabolic rate is a defense mechanism, designed to prevent starvation.

If a person diets, or diets and performs only aerobic exercise, they will lose muscle mass as well as fat mass.  Yet even some "successful hunting" during a lean period can help retain muscle mass.

This study talks about resistance training and protein intake being the keys for the maintenance of lean mass during dieting.  This makes much more sense if you look at the issue from an evolutionary standpoint.

You can think of this as a continuum based on hunting success.  On one end of the spectrum, you have a person who is unsuccessful in hunting.  They are not locating any game; hence, they are not using their muscles in the capture of game, and of course not ingesting any game.  They are most likely performing only aerobic activity and subsisting off plant food.  They will lose fat mass as well as muscle, and their metabolic rate will slow.

In the middle, you have a hunter who is moderately successful in acquiring game, but still does not capture enough to maintain body weight.  This hunter engages in some successful hunting (resistance activity and ingestion of protein and fat), yet not enough total calories are consumed.  This person will lose fat mass but may be able to protect their muscle mass.  However, their metabolism might slow as well.

On the other end, you have a hunter who is very successful in acquiring game.  He is busy utilizing his muscles to capture game and ingesting a good amount of protein and fat.  His body responds by building muscle mass, which advertises to others his successful track record.

Muscle Mass as a Fitness Indicator

About ten years ago, I was thinking about the theory of natural selection and muscle mass.  I wondered from an evolutionary standpoint, what was the point of big muscles on a person?  Muscle mass is "expensive" in the sense that it takes calories to maintain it.  In addition, muscles that are too bulky might decrease movement and speed.  It would seem that that being strong and having smaller, more compact muscles would be preferable to having the same level of strength yet having large muscles.

My general idea at the time was that big muscles served as some sort of visual indicator to others, and that this had implications for reproductive success.  Later, after reading Geoffrey Miller's book, "The Mating Mind," I found a theory to match my idea.  Miller discussed the theory of sexual selection, and how things that may seem expensive and wasteful from the physical side of natural selection are often important in sexual selection and mating.

Some background on Miller's ideas about sexual selection can be found here.  Miller talks about indicators being subject to the "handicap principle," that is they must have high costs to be reliable.  If my theory about muscle mass being a record of one's "hunting success" is true, then muscle mass would also satisfy the handicap principle.  It takes months of physical effort in acquiring game (resistance training) and ingesting some of the game (protein and fat) to build muscle.  In Paleolithic times, this could not have been "faked."

Hence, the fact that muscles are showy and expensive may tell us what their ultimate function is: an ornament in the game of sexual selection.

Protein Timing and Aging

As I hypothesized in my last post, resistance training and protein ingestion would have been linked in Paleolithic times.  This study looks at elderly subjects and how the timing of protein after resistance training can affect muscle growth.  Both groups performed the same resistance training, but one group ingested protein immediately afterwards while the other group waited two hours to ingest the protein.

The result?  Muscle mass increased in the group immediately ingesting protein, while the other group showed no significant increase in muscle mass.

Hunting, Protein, and Muscle Growth

My previous post showed how properly timed protein ingestion is crucial for building muscle.  But why?  Researchers may say there is a "window of opportunity," or that the body is more receptive to protein after working out.  But none of this gets at the true evolutionary reasons underlying muscle growth.

The first step is to understand when our evolutionary ancestors, the hunter-gatherers, would have engaged in something resembling resistance training.  My post on the Ache hunter-gatherers showed a "day in the life" of a male hunter-gatherer.  The morning and early afternoon were filled with lots of walking.  Later in the day, they often engaged in heated pursuit of game.  They may have used weapons to bring down the game or they may have had to do it by hand.  If they were successful in this, they would then butcher the meat, perhaps eat some immediately, and then bring the rest back to camp.

You can follow the chain of movements that led to a successful hunt: walking, sprinting, wrestling or throwing, butchering, and carrying.  The butchering and carrying part is what could be thought of as something akin to modern resistance training.  And this "resistance exercise" which taxed the muscles only took place when a hunt was successful.

From this, you can theorize that resistance exercise and a successful hunt go together.  And this means that resistance exercise and the ingestion of protein and fat from meat go together.  The other main food sources for hunter-gatherers were fruits and vegetables (primarily carbohydrate) and nuts (which do have a mix of carbs, protein, and fat).  But the real payoff food was meat, with its large supply of protein, essential fats, and other important features such as iron and vitamin B12.

The next question is why the ingestion of protein after a successful hunt (resistance exercise) leads to muscle growth.  It  would be easier to understand how this would lead to the maintenance of muscle mass, but not necessarily muscle growth.

My theory is that muscle growth (mainly focusing here on men) is some sort of "indicator" of a successful hunting record.  First, it takes time to build muscle.  Nobody goes to the gym, eats some protein, and blows up like Popeye.  It takes months of successful hunts (resistance training) and the corresponding proper nutrition (protein and fat) to build noticeable muscle.

Further, the appearance of muscle growth differentiates someone who may be fit from someone who is fit but also "brings home the goods."  Let me explain.  Let's say a person is cardiovascularly fit - they can run long and fast.  If that is all the training they do, they will not build muscle.  Muscle growth requires that a person 1) uses their muscles in the process of acquiring game (heavy loading), and 2) ingests some of the game afterwards.

Muscle growth is then a better signal of "hunting success" than is only cardiovascular training.  After all, what good is it if a hunter can run fast and strong but never catches any game? 

Muscle growth also weeds out "fakes" through another mechanism.  And this hinges on the fact that the muscles must be utilized in order to start the process of muscle growth.  This means that if a hunter somehow gets lucky (finds an already dead carcass) or cheats (steals a kill from someone else), their body will not exhibit muscle growth.  This is because they did not use their muscles in the process of acquiring food, and the body does not build muscle without a physical stimulus (even if enough or even an abundance of calories is consumed).  In this way, muscle growth is "honest" - it shows that a person expended effort in acquiring game and was successful.

I'm also thinking there is a feedback loop here, such that "success leads to success."  Let's say that a hunter uses his muscles and acquires game.  He ingests some of the protein and fat and the body builds muscle.  Now this hunter is better-equipped for the next hunt since he has more muscle at his disposal. 

I think this evolutionary theory of muscle growth is a very powerful and very useful framework.  I will be presenting some associated evidence and implications in future posts.