Muscle geeks unite! Many readers know that there's a direct relationship between learning and progress - grasping the "why" and not merely the "how" of change (although we'll see to that, too).
Toward this end, prepare for a bastardized course in "comparative physiology" as we investigate how to become huge and powerful like our reptilian brethren.
It's brutal to the point of disturbing.
Nothing in nature can equal the scene.
Watching a big crocodile rear up and eat a full-grown lion near the waters edge invokes an amalgam of fear and respect.
It's a display of pure power.
It's a lesson in top-of-the-food-chain strength and speed.
Interestingly, serious weight lifters share in such power - at least to a degree.
The amazing anaerobic processes that enable a big croc to eat even other predators also drive power athletes.
But there is a price.
Want to find out what I'm talking about? Let's take a whirlwind tour of a discipline called "comparative physiology".
(I promise to keep the focus on athletes and come to some practical conclusions.
) By learning about extreme species, we can actually improve our own performance.
There's a validated link between knowledge and success, so why not study the extremes of what nature has to offer? Before traveling to the fringes of evolutionary specialization, however, we'll begin with hum drum humans.
When it comes to raw physicality, we humans don't look like much compared to other species.
No claws.
No fangs.
No poison.
We don't even measure-up on muscle mass or strength compared to, say, mountain gorillas or even horses.
Our muscles are the focus of this article, so let's look closer at what little we have.
Average (sedentary) human adults and children possess about 50/50 fast- versus slow-twitch muscle fibers.
(1, 3) That's neither here nor there regarding performance.
People typically have just a moderate amount of glycolytic capacity (for power) and a modest number of mitochondria - the "aerobic powerhouses" of cells (for endurance).
At first glance, an alien observer may well conclude that we're just not much across the board.
Making conclusions from first glances, however, is a bad policy - as we'll find out later.
But before we examine how the seeming mediocrity of humankind can actually become its strength, let's review some biological extremes.
Birds, at one end of the muscle performance spectrum, generally shame us on the endurance scale.
Imagine contracting your pecs repeatedly for thousands of reps.
Birds do.
They avoid fatigue thanks to the freakish mitochondrial density and capillarization present in their flight muscles.
(4, 7, 14) All those slow-twitch, highly aerobic, well-supplied muscle fibers are an evolutionary adaptation that has been meticulously crafted over eons.
Imagine feeling almost zero fatigue after countless contractions.
Amazing.
When it comes to size, strength and power, however, modern birds are just not built to compete.
Small, slow-twitch, Type I muscle fibers and oxidative processes like the tricarboxylic acid (TCA) cycle are limited in how quickly they can ramp-up to meet a challenge.
(Although aerobic systems do contribute sooner during exercise than once thought; there is no exclusive, sequential shift from one energy system to another as many believe.
) But there's more to avian slowness than this.
Maybe we're "flying off course" with all this talk of intramuscular metabolism.
Why? Because provision of oxygen-rich blood becomes another limiting factor, regardless of what's going on inside a specialized muscle - at least for we humans.
That is, a hugely-proliferated cellular "furnace" (mitochondrial matrix) only goes so far when the supply of oxygen depends on multiple other factors.
No furnace or flame is going to burn too brightly when put under a glass, pinching off its air.
Similarly, we humans could use extra "ductwork" (blood vessels) in this regard, even beyond what we can create via endurance training.
(By the way...
for you brainy muscle geeks who care, mitochondria don't exist as individual bean-shaped units like many folks think but rather as an inter-connected matrix like I mentioned.
) But let's get back to the croc, shall we? Crocodiles differ dramatically from birds and even humans.
Far from being aerobic machines, these creatures often rely on comparatively inefficient anaerobic metabolism.
Here's a nifty quote: "...
reptiles outstrip their aerobic capacities with any exercise more intense than a slow walk" (2).
Niiice! This reminds me of my brother, The Yeti, back when we were singularly power training and perhaps getting too big, too fast.
Have you ever seen a seemingly fit man grab his knees and pant helplessly after climbing a single flight of stairs? Now THAT'S training specificity! Unfortunately for crocs, providing huge quantities of energy (ATP) without "burning" a substrate like carbs or fats in the TCA and electron transport system (within their mitochondria) is rough.
And yet nature has found a way.
First, of course, is the creatine-ATP system.
There's nothing like "raw energy", even if it does only last a few seconds.
Then there's an increasing contribution of energy from direct breakdown of carbohydrate.
By investing two ATP early in this process, it's possible to generate four ATP by the "end" of anaerobic glycolysis.
It's a worthwhile investment: two in, four out.
But there's a much more fascinating aspect to anaerobic glycolysis (and glycogenolysis).
Oxygen be damned, anaerobic energy production can still ramp-up several fold.
(8, 19, 20) Need energy right now to catch that meal? YOU GOT IT.
Need to out-sprint and out-muscle any other beast? YOU GOT IT.
Coupled with that full-bore ability to use creatine phosphate and rifle through (hydrolyze) ATP, you're now the true king of the jungle.
But now the rub.
After their freakish displays of power, crocodiles lie around panting all day.
(2,13) The lactic acid build-up in their bloodstreams would reportedly kill a human.
Wow.
And all those hydrogen ions flying off the individual steps in glycolysis create muscle-burning, metabolism-stopping acidity that keeps the blinding effort extremely brief.
It's the price of power.
Some of us, however, choose power - whatever the cost.
After a decade or so working with fellow exercise physiologists, I've become accustomed to occasional ribbing about my poor aerobic capacity (VO2max).
My reply takes one of two forms.
One may sound too aggressive and the other too vain, but here they are: A.
) "Would you rather have a hummingbird or a crocodile on your side in a fight?" ...
ahh, food for thought...
or B.
) "In case you haven't noticed, no one can see your VO2max.
" Building massive and powerful muscles has both survival and social implications.
Of course, I never begrudge runners, swimmers or cyclists for their friendly taunts because we both know that I could pin-down and devour a half-dozen of them at will.
Even if it did require a half-hour to recover.
So much for keeping this discussion limited to animals, eh? So, there's your brief "sprint" through several facts to set the stage.
I hope I've whet your appetite; I have to rest and recover now.
Stay tuned for Part II on how to become the crocodile.