“Knowledge is of no value unless you put it into practice”–Anton Chekhov (Russian master of the modern short story 1860-1904)
You’ve been told. Now do work!
Coach A and I do not coordinate what we write on here with each other but this time things have fit very nicely. If you have not already done so, Coach A has written an excellent article on why we train, and in there he lists some benefits of training/physical activity. I am about to elaborate on one such reason why exercise is vital for you. Today we are talking about our bones.
When most young people think about training, 99% of the time they will think of those muscles they are sculpting and how those muscle fibers are getting thicker and able to contract faster and harder, but seldom do we think about the support system that is holding this all together, our skeletal system.
Many of you I’m sure have seen little old grandmas walking around Japan who look more like a question mark when they are standing. Now I understand the historical context of lack of nutrients and food for people of that era, but a lack of exercise has done that to them. How many mature people do you know who have fallen and broken a bone? Countless. If you want to know how to do all you can to prevent that from happening to you, read on dear friend.
Let’s talk about our bones. Ossification (or bone production) begins when you are an infant. Did you know however that all of your bone at the start was cartilage (the stuff that makes up your ears and nose now) and fibrous structures. Eventually this cartilage is replaced by bone with a calcified bone matrix. This is where things start to get a bit tricky but I will try to explain it the best I can. Bones contain round shaped structure units called Osteons which surrounds blood vessels and nerves (called a central canal). Basically the framework of your bone is made by many of these osteons cemented together. Because of the central canal, living bone cells are able to receive nutrients and remove waste from cells that are essentially trapped (but metabolically active). Each osteon is made up of 4 components, the Lamellae, Lacunae, Canaliculi and the Central Canal.
1. Lamellae: These are layers of calcified matrix. In all connective tissue, there are cells, fibers and extracellular material (aka matrix). Bone tissue however is unique because its matrix is calcified or hard (actually in bones, there is much more matrix than there are cells). The matrix contains fibers and collagen (which you will often see being advertised on TV for the strengthening of bones and joints, or reduction of wrinkles) and is made up of two types of materials, inorganic salts and organic matrix. Inorganic salts give it the hardness, with calcium and phosphate deposits (this why your Mum used to force milk down you at breakfast). Organic matrix consists of collagenous fibers and a mixture of proteins. Lamellaes can either be between the osteons or around the inner and outer circumference of a bone.
Lacunae: Small spaces in the matrix that contain tissue fluid.
Canaliculi: Ultra small canals that run from Lacunae to the Central Canal.
Central Canal: As mentioned before, this runs lengthwise through the centre of the osteon and is lined with blood vessels, nerves and lymphatic vessels. This allows nutrients and oxygen to reach bone cells.
Whew, ok Coach what now. Now comes the quite interesting bit, did you know that your bone is constantly remodeling. There are two bone cells, osteoblasts and osteoclasts that are constantly working on your bones. How this works is that the osteoclasts erode existing bone material, while osteoblasts are simultaneously forming new bone on its under surface.
How does this apply to fitness training? Here is the even more amazing bit. Because your bones are always being eroded and built up again, they are able to sculpt or adapt their shape depending on how much stress is put on them. Bones are able to change their size, shape and density. Not surprisingly exercise increases the rate of bone deposition, hence why athletes have denser bones. What it might mean is that your bone gets denser, or the site of muscle attachment might get larger or your bone may reshape itself to withstand the stress put on it. How does this work? Well, a bit more technical stuff but bear with me. After the early forms of calcification, the bone is soon replaced by a stronger type of bone called lamellar bone which is characterized by having many osteons (remember them?). To form a primary osteon, osteoclasts (remember those bone eroding cells??) erode a cone or tube around a blood vessel (sounds a lot like the central canal to me…) and that hollow bit is filled with collagenous fibers (organic matrix??) and osteoblasts build new bone around the outside of the existing bone, trapping osteocytes between the lamellae. Eventually there is no more space and it is tightly packed around the blood vessel.
When mechanical stress is applied to the compact bone and remodeling occurs, it causes secondary osteons to be formed. The higher the load, the narrower the tube hollowed out by the osteoclasts as they make the new osteon. The narrower osteons have much denser minirelization and combining that with the increased number of osteons leads to denser, stronger bones.
Having dense, strong bones is good. Very good in fact for your future. As a child and adolescent, the rate of bone deposition is higher than the rate of bone erosion, meaning your bones grow in size and strength. At about 35-40 years of age however, this process reverses, and bone loss exceeds bone gain! Bad luck to those of you who though “hey I’ll just wait until I am older to do some physical activity and I’ll be all good”. My lecturer said to think of it as a bank. When you are young you are able to deposit, but once you get older, that’s it, it’s hard to (and in bone sense impossible) to add more to your savings as you need to use them to live. The more you have, the more comfortably you are going to live. Simple as that. Think of the bent over grandma I mentioned at the beginning. She probably did not have a lot of “bone savings” to work with, hence her bones are weakened, prone to breaking and that combined with other diseases and medical complications is not what you want. (More on that in another post). She certianly had enough ‘bone savings’ though.
So what to do from here. Simple, do physical activity and eat well. Join the Mugen Fitness Family, CrossFit, play a sport, talk your dog for a walk, ANYTHING physical is better than nothing. But remember, the greater the mechanical stress, the denser it gets. Hmm, do I hear heavy back squats calling?? Also, don’t smoke, drink excessively or take steroids. All of those things can weaken your bones. Over exercising is also not good for your bones. Don’t try to increase your ‘bone savings’ by doing heavy squats every hour on the hour. No need for that, everything in moderation please.
Hope you learned something, I know posting this is helping me learn! We’re here to help you so contact us with any questions.
Coach ‘bone savings’ (I like that I just made it up!) J
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