How Genetic Influence how we Look--Part 1

When we speak about the results of our training being highly dependent on genetics, we're talking about an number of different things--many of which we don't yet fully understand. Much research has been conducted over the past hundred years or so by many people smarter than myself. And yet... understanding the chemical processes behind exercise performance and physiology is still not anywhere near being totally understood. This is because there are too many variables. Each human body comes complete with its own inherent gifts and challenges. Each person is different and therefore each person reacts to exercise (and nutrition) slightly differently.

However, there are a handful of variables that have identified as being significantly impactful when it comes to building muscle and/or losing weight. And because we can identify a handful of the most significant variables, we can also develop a set of exercise principles that are going to work well for the vast majority of people--if not all people, with a little tweaking for each person, of course. Those variables are the following:

Muscle length
Muscle fiber type
Bone Structure/thickness/density
Hormonal levels.

Now, each variable has variables of their own and when I'm discussing these variables in this post, I'm going to be simplifying descriptions of each, because, ultimately, we don't need to know the exact science behind each variable to help us understand them. We just need to get the general "gist" of how each variable impacts each of us.

First off: Muscle fiber type. Many people are familiar with the concept that we are born with two different muscle types--so-called fast twitch and slow twitch fiber types. Many people even have a general understanding of how each person is born with different ratios of both types and that, based on that ratio, determines some of their athletic performance--i.e. people with higher ratios of fast twitch to slow twitch muscle fibers tend to be faster runners, while those with more slower twitch fibers tend to be better at long-distance running.

What very few people know, however is that A: there are actually at least 4 types of muscle fiber types (many exercise physiologists think there may be even more that we haven't been able to discover) and that your ratio of muscle fiber types not only impacts athletic performance, but--more importantly for our purposes--how our bodies respond to exercise.

(Quickly I just want to note that the 4 types of muscle fibers are Fast Twitch A, Fast Twitch B, Fast Twitch AB and Slow Twitch. Fast twitch A is the "slowest" of the Fast Twitch fibers while Fast Twitch AB is the "fastest." It is also this general knowledge of Fast Twitch and Slow Twitch physiology that leads many people to think that you have to train "fast" to be "fast." Which isn't true at all. What's most important during exercise for training for "power" is efficient recruitment of all muscle fibers--including Fast Twitch, obviously. To recruit all muscle fibers, it is only necessary to train with enough load and to train safely to failure. Training "fast" only makes one vulnerable to injuries, and, I think, I just discovered what my next blog post will be about....)

The ratio of Fast Twitch fibers to Slow Twitch fibers determines how quickly we recover from exercise. It's a trade-off, really, because those with higher ratios of Fast Twitch fibers can exercise more intensely and can usually lift more impressive amounts of weight, but, it is precisely because of those reasons that it takes them longer to recuperate after an exercise session. Those with slow twitch fibers cannot contract their muscles as intensely, and it is because of that lack of intensity that they have a tendency to recover well from exercise. The other trade-off, as already touched upon, is that those with high ratios of FT fibers don't need as much Time Under Load to get good results, whereas those with more ST fibers need longer TULs. People can and do have different ratios of FT and ST fibers in each specific muscle group, and so good record keeping of exercise performance helps to determine the best protocols for each muscle group.

Second: Muscle Length. How this impacts how we look is because it determines the length and therefore size of a particular muscle. People with long muscle "bellies" and shorter tendons are generally able to develop more impressive musculature. For me, I tend to find it easiest to observe this phenomenon in the summer time when people are showing their calf muscles. I used to get so frustrated with the size of my calves. I used to do calf raises until the sun came up and still they wouldn't really grow and it looked as if I had the proverbial "chicken legs." During the summer months I would get upset when I'd check out women in shorts or skirts and even though I weighed more than them, their calves were still more impressive than my own.  However, now that I understand the role muscle length plays in physique, it doesn't bother me as much. I was born with small muscle bellies on my calf muscles, just as I was born with girlie hands. Sometimes you just have to get over these things.

Anyway, below are pictures of Frankie Edgar and Chad Mendes. These two men are the same height (5'6") fight at the same weight class (145lbs) and walk around (prior to cutting weight) at around the same weight (165lbs-170lbs). However, Mendes appears to have longer muscle bellies and therefore has a somewhat more pronounced musculature, particularly in the arms and neck.

Again, as it is with muscle fiber composition, muscle length is not uniform inside each of our bodies. In fact, there are tendencies. For example, most people find that they can either develop big, strong-looking torsos while they struggle with their arms, or they find that they can build big arms while struggling with their chest and back. I am a victim to the former, myself. Those of us who are genetically gifted have long muscle bellies in both the arm and torso muscles.

This post ended up being a bit longer than I had anticipated. So for the next post I'll discuss how and why the way bone structure and hormonal levels impact the way we look and how we respond to exercise.