Muscle Mania Part I: Myology 101
All Aboard the Gains Train.
It’s interesting how willing we are to throw around our opinions with such high levels of confidence regarding certain subjects; whereas, in other instances, we have no issue admitting ignorance and playing observer in true Swiss fashion. For example, unless they happen to be a Japanese Architecture professor, I imagine most people won’t pony up too many strong opinions amidst a discussion comparing kirizuma vs. irimoya style roofing. On the other hand, if something closer to home (pun intended) comes into conversation, like diet or exercise, many people are inclined to espouse statements with expert-level confidence despite being almost equally as incompetent in the subject of concern as they were in the prior scenario. In the world of health and fitness, where everybody has, “THE DIET,” or, “THE TRAINING PROGRAM,” or, “THE (insert life-saving health intervention of choice),” and where everybody is an expert because they have plenty of experience eating, moving, and living, it can be difficult to separate science from snake oil. This becomes a pertinent issue when you are trying to change your weight or improve your fitness because, afterall, who do you listen to? Who really knows best, what really works, and how can you tell?
For this reason, I’ve decided to focus this next deep dive series on the science and methodology behind the process of growing muscle, formerly known as hypertrophy. If you’re interested in how to build muscle, whether it be for athletic purposes, improving your health and longevity, or changing your body, this series will take you on a journey through hypertrophy science and its applications, so you can navigate the muscle-building aspect of the previously mentioned chaotic world of health and fitness.
Medical Disclaimer: I am not a medical professional, and none of the information below is medical advice in any way, shape, or form. Let this post serve as a spark to your curiosity and a stepping stone to conversations with your personal medical providers.
Meat the Players
Before we dive into the molecular mechanisms and nuances of muscular hypertrophy – before we can describe what hypertrophy is – we should understand the machinery we are investigating. When I look at the anatomy of a muscle, I think of a Russian nesting doll, except – rather than dolls housing smaller dolls – the layers consist of cylindrical bundles containing straw-like structures. If we zoom all the way out, we start with the muscle belly (the thickest portion of the muscle), perhaps the fan favorite biceps brachii that you boast while flexing in the mirror or a head of your quadriceps femoris. These muscle bellies are all composed of bundles of muscle fibers, called fascicles, and those muscle fibers, also referred to as myofibers, are the actual muscle cells that comprise your guns and tree trunks. As we peel back the next layer, we find that the muscle fibers exhibit a similar structure to the fascicles, in that they too contain a bunch of small units within them, this time called myofibrils. This design continues down into the next structural level, as those myofibrils are composed of a bunch of myofilaments – the proteins of the muscle tissue – organized into structural units called sarcomeres. In this way, similar to the design of a Russian nesting doll, a muscle derives complex function from a simple but amplified form. Check out Image A below to put all of this anatomy into visual perspective.
Now that we know the structural machinery, let’s look at what grinds the gears: myofilament motion. Those myofilaments we just discussed are proteins that produce the contractile functions associated with muscle tissue, and their mechanism of action is outlined by the Sliding Filament Theory. Although many myofilaments play a role in muscular contraction – such as titin, troponin, and tropomyosin – myosin and actin take center stage in this process, as it is the loading and cocking of myosin heads upon actin filaments that create the actual motion that breeds the contraction. I picture these sliding myosin motions as micro versions of a low crawl where a person would reach and grab ground in front of them and use their arms as levers to slide themselves and the ground past each other – the lever arms being analogous to myosin heads and the ground being analogous to an actin filament. In order for a muscle to contract, myosin heads attach to actin filaments and conduct what is called a power stroke motion, where they slide the actin filaments inwards and pull the two ends of the sarcomere towards the sarcomere’s center as a result. This process shortens the entire structure and produces a micro-contraction, which contributes to the whole muscle’s contraction when executed in unison with many other sarcomeres. Look at Images B-F below for a visual depiction of how myosin heads interact with surrounding actin filaments via the Sliding Filament Theory.
So, if we return to the zoomed-out flexing of the previously mentioned muscle bellies that we see in the mirror, we now recognize those movements as the sum of millions of myosin heads sliding down their surrounding actin filaments to squeeze the muscle into contraction. And, it is the structural design of those millions of myofilaments into sarcomeres that enables them to work in unison to produce that ultimate contraction with great force. Now that you understand muscle anatomy 101, it will be easy for you to understand the name of the game when it comes to muscular hypertrophy: growing muscle tissue by adding sarcomeres to your muscle fibers.