You can’t lengthen your muscles. I’m sorry for all people who say they have short muscles. They won’t get any longer; no matter how much stretching you do. That’s the bad news. The good news is: you can make them ore flexible.
Short muscles, long muscles: it’s just a myth. Every bodies are attached more or less on the same place. Hamstrings for instance start on the sitting bone and finish on the tibia and fibula. If you truly could have short muscles, they would have to attach higher up in your leg; somewhere on your thigh bone as well. But then you wouldn’t be able to walk. At the same time: if you had long muscles they would hang loose in your body. People would have their hamstrings hanging somewhere at the back of their knees.
Lengthen your muscles
Yet your muscles can become more flexible. Figuratively you can lengthen your muscles. As far as science knows now – It’s still a topic that is under research – what you do is ‘reprogram’ your muscles. What happens when you stretch is that your muscle is sending a warning to your brain as soon as it thinks it’s going to be overstretched. You feel this warning as pain and you back off. If you do so, the muscle had done its job. It has protected you of over stretching. What decides how deep you can go, is not your muscle. It is actually your nervous system.
If you stretch often, your muscles will ‘see’ it’s safe to go a little further. The ‘safety warning’ will come at a later point. So you can stretch deeper, without experiencing pain. If you keep on stretching, the muscle will allow you to go a little deeper every time. So what you are doing is reprogramming your ‘safety’ device instead of making your muscles longer.
How flexible you are is for a big part genetically determined. At this moment we will only look at the muscle itself. About 85% of the mass of a muscle is made up of muscle fibers; the remaining 15% is mostly connective tissue. This connective tissue is made up out of collagen reticular and elastin fibers. Elastin is flexible, collagen not. The ratio collagen/elastin is different from person to person. The more elastin you have in your connective tissue the more flexible you are by nature.
So are your DNA and your nervous system running the whole show? No. There is one tiny, tiny other thing in control and
that’s a sarcomere. A sarcomere is the basic contractile units of your muscles. To say it simple: they make you move. What they do as well is adjust to your movement. So is you sit in a chair all day with your legs bend the sacromeres in your hamstrings will adjust to your chair-shape and see your bend legs as normal. So they shorten. You can only counteract this by actively lengthening your muscles. But if you sit on a chair for 10 hours a day an hour of yoga is not counter productive enough. You not to do more. For example: work at a standing desk, sit on the floor with straight legs, walk instead of taking the car and so on. Only that way you can reprogram your short muscles into long muscles.
You’ll find more yoga anatomy on the Teacher Training Course page.