"Muscle Fibers, Genetics and Your Training" (Blog #132)
The human body has approximately six-hundred and fifty muscles. These muscles allow us to walk, talk, eat, train, go to work, and laugh. Our muscles are connected to bones via ligaments and tendons. The difference between a tendon and a ligament is that a tendon connects muscle to bone, while a ligament connects two bones. Tendons let your muscles move bones, whereas ligaments stabilize joints.
The reason most of us lift weights and train so hard is to make our muscles, ligaments and tendons stronger, and our body fat lower. Training strengthens everything from your bones to your heart, and is the true fountain of youth. Proper weight training will act as a catalyst for certain hormones (lipase, HGH, Testosterone, Serotonin, etc,) to be released while we sleep (and recover) that promotes fat loss, bone strength and stronger muscles. Hence why after a few weeks/months of training, you are able to perform those everyday, menial tasks with much greater ease.
Obviously, if you're reading this blog you probably already know that training is good for you. But here are a few things that you probably didn't know about your muscles. Every human is born with muscles, but we are not all "created" equal. Some of us are born with predominantly Type 1 muscle fibers, and others are born with more of the Type 2 kind. What the heck does that mean?!
Well, lets talk about the difference between type 1 fibers and type 2 fibers...
People have two general types of muscle fibers: slow-twitch (type I) and fast-twitch (type II). Slow-twitch muscles help enable long-endurance feats such as distance running, while fast-twitch muscles fatigue faster but are used in powerful bursts of movements like sprinting. This is why you'll never see any long distance runners breaking any world records in the barbell back squat anytime soon, and you wont see the worlds strongest bench pressers running a marathon. These humans are designed differently, not good or bad, just different muscle fiber types and different types of training.
Lets have a quick overview of the different types of muscle fibers again so that you guys fully understand them. Not to get too confusing, but we are actually learning more and more about the muscles everyday. The easiest way to look at them is to break them down into three categories:
Type 1 Muscle Fibers / Slow Twitch: (they contract slowly) / They are more red in color due to their larger blood/oxygen content / Resistant to fatigue for long periods of time as long as oxygen is present / Think of Endurance Runners when thinking Type 1 fibers.
Type 2(a) Muscle Fibers / Fast Twitch: (they contract quickly) / They are more pale in color because they carry less myoglobin (oxygen storer) / White fibers fatigue quickly because they rely on short-lived glycogen reserves in the fiber to contract / However, they are capable of generating much more powerful contractions than red fibers / Think of Sprinters when thinking Type 2 fibers. But Type 2a fibers still share some characteristics with Type 1 fibers when it comes to endurance.
Type 2(b) Muscle Fibers / Fast Twitch: These fiber types are very explosive and short lived / They are great to produce very short bouts of very explosive movements / These white muscle fibers fatigue extremely quickly but are great to produce power and strength when needed.
So now that we have a better understanding of muscle fiber types, you're probably asking yourself "What type am I?" Well, you probably have a mixture of both like most humans do, but we all may lean a little more Type 1 or lean a little more Type 2. Also, your training can make differences to your fiber type as well. You may never make that LSD runner a power lifter, but if that runner starts to train like a power lifter, he or she would start to change their fiber types to some extent and vice versa.
Again, one type is not necessarily better than the other, but it's a good idea to train all fiber types. Doing your long slow distance training, mixed with weight training and intervals training is all good. In fact, switching up your reps, sets, rest periods and style of training (running, lifting, hills, swimming, etc) is the ideal way to get strong, lean and avoid those overuse injuries.
If running is something you hate and you're just not good at, there's a good chance that you dominate type 2 muscle fibers; but you may be a beast when it comes to weight training. The same can be said for you if you just aren't strong, you may dominate type 1 fibers and may be better at longer distance activities. Not good or bad, just different! But this doesn't mean that you can't GET better in the weight room or on the trail. If you put the work in consistently, you will improve dramatically and your fiber types will begin to adapt.
Pop Quiz: Can you guess which one is the Sprinter and which one is the Marathoner?
This pic has become very famous over the years. The man on the left would dominate the man on the right in a long distance race, and the man on the right would dominate the man on the left in a Sprint. Again, it all depends on your goals, your training and your genetics. For us average Joes/Jane's, train both ways and be a beast!