A client of mine asked me about his blood sugar yesterday and it occurred to me that writing an overview of blood sugar is in order (since I rant so about keeping insulin levels low, avoiding concentrated sources of carbohydrates, etc.).

First, what’s normal blood sugar?

The normal range for a fasted state is between 80 to 120 mL/dl. After eating, blood sugar generally jumps a little higher but not much, although if you load yourself up with sugar it can and will skyrocket (as much as 200 mL/dl). If you’re normal (i.e., non-insulin resistant), your blood sugar level is probably less than 100 mL/dl and will not rise past 140 mL/dl after a meal.

100 mL/dl is the “standard” that most general practitioners use, but diabetes specialists will ring alarms if your fasting blood sugar values exceed 83 mL/dl.

Why does blood sugar matter?

If you’re a regular reader of this blog, you already know the answer to this question. Having high fasting blood sugar levels shows insulin resistance, and insulin resistance is the first step down a road you definitely don’t want to take.

A recap:

All (not just the bad ones, but all) of the carbohydrate you consume gets broken down into glucose - the building block of carbs. When all goes well, glucose is absorbed from your bloodstream into your cells to be burned as energy. Insulin is the hormone that makes this absorption possible - it literally “opens the door” to your cells, allowing glucose in.

When all is not well (i.e., when you overconsume carbohydrates, particularly refined carbs), you end up with large amounts of glucose in your bloodstream. Normally, the body deals with glucose by secreting (more than) enough insulin to pull all of that sugar out of your bloodstream and into your cells to be used as energy or to be stored as glycogen. When you run out of glycogen storage space, your body simply repackages that glucose as triglycerides and socks it away in your fat cells.

Fat gain may be inconvenient, but it’s not the main issue here. The problem is insulin resistance - when cells grow immune to insulin’s effects and insulin can no longer ferry glucose into the cells. Chronic hyperinsulimia - high levels of insulin in the blood - is the root cause.

In short:

High blood sugar -> High Insulin -> Insulin Resistance -> Diabetes (and other diseases of civilization)

Sounds terrible. What can I do to prevent these insulin spikes?

The simplest way is to curb your dietary intake of carbohydrates. In other words, minimize consumption of grains, sugars, and starches.

If you do choose to consume carbohydrates, eat the “best” kinds: High in fiber and least refined (e.g., whole wheat pasta, brown rice, etc.).  As always, “real foods” are best.

Get the majority of your calories from meats, non-starchy (aka leafy) vegetables, low-sugar fruit, nuts, and seeds. Beans and legumes are ok; they’re high in fiber and relatively high in nutrients, but they also contain phytic acid, which can block absorption of nutrients.

Exercise helps by making your cells more insulin sensitive - in other words, exercise improves the ability of insulin to pull glucose into the cells.  So do it.

The $1000000 question: So if I eat mostly carbohydrates, I’ll get fat and die prematurely?

Ah, I knew you were going to ask me that eventually.  The answer is, it depends.  If you’re like my friend Andrius and the carbohydrates you eat are leafy greens, fruit, legumes, and low-GI starches and grains (e.g., sweet potato, quinoa, etc.), then probably not.  But if you’re like the average American or Australian and the carbs you prefer are soda, white bread, fried potatoes, or anything that comes in a box, then the answer is “likely.”

If you like short and easy to remember admonitions, here’s what this post boils down to:

Avoid refined starches, grains, and sugars.

Above: Could he really medal in any event in the Olympics? Dr. Paul Zehr would say so.

Ronen sent me this neat-o article on the physiological basis of Batman. Don’t take it too seriously; it’s just some light-hearted conjecture (real science, of course) on Batman’s physical abilities by an associate professor of kinesiology and neuroscience. Enjoy.

Ken (a very spry 70 year old) asked me, “How does strength training increase bone density?”

Well, the basic mechanism is very simple: Think of your skeleton as the framework of the body, the base upon which the body is built. Load up that framework with weight, and the body, being that dynamic organism it is, makes the framework stronger. Certainly an explanation you’ve heard before from your doctor, your trainer, or your media talking head of choice.

Here’s the implied but rarely mentioned “twist” that makes this all possible: Your bones are alive.

Not in a Night of the Living Dead creepy sort of way, but alive just like the rest of your body’s cells are (save hair and some skin cells). Bone isn’t some inorganic matter like the 2 X 4s in your bed frame or the piping under your kitchen sink. It’s a dynamic, ever-changing organ, constantly building and breaking itself down.

Cells called osteoblasts and osteoclasts work 24-7 at reshaping and remodeling your bone structure (even after you reach full adulthood). Load a bone with a heavy weight, and osteoblasts lay down new bone tissue to reinforce the points of stress, much like a young beach-going lad would add more sand and water to reinforce a wall of his sand castle. Repetitively load a bone in the same way, and you make that bone stronger by stimulating osteoblast activity, over and over again. Over time, these osteoblasts lay down so much new bone tissue that they trap themselves in it, becoming osteocytes (which always remind me of this). Not to worry for our osteocytes, however; they continue to chug away and do their job of reinforcing bone in a less…mobile…fashion.

Osteoclasts have a less celebrated but equally important role: They break down bone tissue by acidifying the bone matrix, releasing its constituent minerals into the bloodstream. Now, why would a fine, upstanding cell like an osteoclast want to do something like break down bone tissue? Well, low levels of calcium ions (one of the main minerals in bone) would be one reason. Calcium ions feature heavily in intracellular function, from DNA transcription, neurotransmitter release, and (most importantly for our discussion) muscular contraction. If you don’t have enough calcium available, the body simply draws from its calcium stores, and the largest calcium stores in the body? You guessed it: Bone.

(Aside: Why are osteoclasts always depicted in mechanism diagrams as goofy-looking Metroids?)

Without going into the ridiculously complex and numerous mechanisms for osteoporosis, let’s just say for brevity’s sake that you want to stimulate osteoblast activity, not osteoclast activity. And strength training just happens to be a fantastic tool for doing just that.

And now, you know why.

What is the magical allure of a 5 x 5?  Or a well performed set of 15 reps?  How do I choose how many reps to do in a given set and what is the rationale for using one or the other?

Moreover, why do you never (intentionally) see a set of 17? Or a set of 9?

One could argue that rep numbers are a matter of human beings’ preference for “ideal” numbers - 1, 3, 5, 10, 12, 15 - those numbers seem “nice” somehow; more intrinsically …pleasing… than a set of 4, or a set of (heaven forfend) 13 reps.  But rep selection has nothing to do with the human heritage of symbolic numbers like 3.  It has to do with time.

The numbers of reps you do is determined by your set time.  Long ago, exercise physiologists figured out that the time frame for anaerobic work (i.e., the energy system in which intense muscular contractions can take place) was anywhere between 30 seconds and 120 seconds.  Let’s keep that thought in mind and do a little math:

Assume that you perform a rep by taking 2 seconds to lift the weight and 4 seconds to lower it.  That’s a total of 6 seconds per rep.

Assuming you perform each rep uniformly, you would get 5 reps in 30 seconds and 20 reps in 120 seconds.  In other words, the majority of set/rep schemes falls squarely in the range of optimal muscular stimulation.  Not only that, but if you do a few additional calculations, you find:

• 8 reps = 48 seconds (0.75 minutes)
• 10 reps = 60 seconds (1 minute)
• 12 reps = 72 seconds (1.25 minutes)
• 15 reps = 90 seconds (1.5 minutes)

Which are nice, round, easily-measured time intervals, whereas 17 reps = 1 min and 42 seconds, which is just plain weird.

Serendipity is a beautiful thing.  Of course, you could argue Thomas DeLorme chose 10 reps because 10 was a nice round number.  But I like to delude myself into thinking he was merely being a good scientist.

Some of you might argue, “Wait - I saw this big guy lifting and he sure as heck wasn’t doing 6 second reps.” 

The speed of the rep doesn’t matter (for the sake of this argument) - what matters is the total time you spend “under load.”  So long as you’re falling in that optimal range*, you’ll stimulate muscular growth.

Back to the original question: How do I know how many reps I should do in a set?  The answer: It depends.  That will vary according to your goals (e.g., trying to lift the heaviest weight possible once vs. preparing for an MMA fight), but for most people (who just want to look and feel better), any rep range that allows you to fall within that 30-120 second range will suffice nicely.

Stated differently, it doesn’t matter whether you do 5 reps, 10 reps, 20 reps, or 1.25 reps, so long as 1) you’re working hard on those reps and 2) the weight you lift increases over time.

Q: “What about the whole low reps for mass, high reps for definition argument?”

A: Low reps will allow you to lift heavier weights than do higher rep ranges.  Since intermuscular tension is paramount in increasing muscle mass, it makes sense that consistently lifting heavier weights will result in greater increases in muscle mass.  Incidentally, your muscles will also grow with progress at higher rep ranges; it’s just more difficult for most to achieve the kinds of hefty weight loads that really stimulate big muscle gains with higher reps (20 rep breathing squats, anyone?).  Less weight lifted = less muscle built. It’s not some special property of the rep range, and performing a greater number of repetitions won’t magically burn off all the subcutaneous fat that is hiding your muscles from view.

*Addendum: Some savvy readers will recognize that certain populations like Olympic weightlifters still manage to get muscularly impressive while falling far below this 30-120 second set time (try 1.25 seconds).  Note that while not falling strictly into that time frame, weightlifters still lift lots of heavy things, and they do so many, many times.  Additionally, the weights they lift increase over time.  So in their case, they’ve got all the parts of the formula except this theorectical “optimal time frame for hypertrophy.”  Muscular growth happens to be a side effect of the practice they do for their sport; they aren’t purposely trying to increase their muscle mass.

Peter’s latest post on his blog Hyperlipid is simply incredible; if you’re science-minded at all (or fancy yourself idiot savant in biochemistry) check it out.

For the rest of you, here’s a summary:

A question - If insulin acts as a gatekeeper for fat storage (by increasing levels of alpha glycerol phosphate), then how is it possible to gain weight on a low-carb diet (where insulin levels are automatically kept low via diet)?

A proposed answer - ASP (Acylation Stimulating Protein).  This enzyme stimulates fat storage by fat cells and while it does seem to be associated with insulin levels, seems to do its job independent of insulin, mostly in the period after meals. 

If this is the case, it opens up a pathway for fat storage aside from high insulin levels, explaining why it’s possible to gain fat on a high-calorie low-carb diet. 

All this is just highfalutin’ science stuff for me to geek on; the implications to someone looking to lose weight are unchanged - that is, that omitting grains, sugars, and starches from your diet doesn’t give you the license to pig out on bacon and pork rinds.  You still have to watch your caloric intake.  You’re just more likely to taste success with a low-carb approach because:

1. You won’t be stimulating insulin secretion, so you’ll be minimizing appetite
2. You’ll be more sated due to higher fat content in the diet (i.e., not as hungry)
3. You’ll be eating foods that are more nutrient dense (meat, vegetables, fruit) in lieu of foods that are less so (carbs).

To repeat - if you want to save yourself a headache - if you overconsume calories on a low-carb regimen, it is possible to gain weight, so don’t do it.