Often students will ask their Yin Yoga teacher a question; “should the muscles be cooler or warmer before we do a yin practice?” The answer, predictably, is “it all depends!” But let’s suppose the reason you are doing a yin practice today is to target your physical body, to get more stress into the ligaments and the joints, as opposed to practicing in order to calm the mind at the end of the day. If the benefits you are searching for are physiological, then it is indeed better to have the muscles cool.
The next questions, invariably, are: Why? Why should the muscles be cool? Why don’t we warm up before Yin Yoga? We are told to warm up before every other form of exercise! Good questions! We warm up before Yang exercises to allow the muscles to more easily stretch. When the muscles are cold, as everyone knows, we feel stiff and tight. Aggressive stretching of stiff, tight muscles could damage them. So it is a good idea, in a yang practice, to take time to warm up the body … but remember, yin is not yang. What works in one practice is not necessarily the best in the other practice.
Here is a simple way to demonstrate why doing your Yin Yoga while a bit cool is actually good for your body physically. Find 3 elastic bands of varying thicknesses and strengths. Two of them should be of similar lengths, as shown in this picture. As you can see here, the middle blue elastic is quite thin, and is easily stretched. The bottom, tan colored one is thicker and stronger. The top, shorter white colored one is very thick and doesn’t stretch easily at all.
Symbolically, the top, white elastic is going to represent your ligaments or joint capsule. The other two elastics will represent your muscles: the bottom tan elastic is your muscles when cold or cool while the blue middle elastic is your muscles once they are warmed up. As we know, warm muscles stretch further and more easily than muscles when cool. And the blue elastic, being thinner, will also stretch further and easier than the tan, thicker elastic.
We now have all we need to simulate cold muscles versus warm muscles.
When we apply a stress to our body the stress will show up as a stretch, to some degree, in the muscles and a stress on the ligaments and joint capsule.  How much the muscles stretches depends on how warmed up it is. However the ligaments and joint capsules don’t (we hope!) actually stretch in response to the stress placed upon it.  The point of stressing the deep connective tissues in this way is not to stretch the tissues but to place tension on them so that the body responds by making the connective tissues stronger and thicker, and even longer, over time. We do not want the lengthening of the deep connective tissues to occur right away: it comes gradually. However, to depict the stress on the ligaments, we will simulate that stress by showing a stretch in the white elastic, which is the thickest, least stretchy of the three. Please remember though, this is not meant to suggest the ligaments actually stretch … it is just to represent the tension put on the tissue.
We are almost ready: once you have the elastics, loop them together as shown in the first picture. Then get a ruler, just so you can measure the effects of our little experiment. Now we are ready!
The Experiment: Cold Muscles vs Warm Muscles!
Hold one end of the ligament (ie: the white elastic) down at the zero point of your ruler. Loosely stretch the warm muscle (blue elastic) to the point where it naturally goes without putting any real stress on it. Note how long they both are. In the example shown here, they both take up about 14 centimeters (around 5.5 inches for our non-metric cousins). Now, apply a stress and stretch them until they are about 25 centimeters (~10 inches) long. Now, carefully note how long the ligament has become.
Do you see much change?
In the examples in the pictures, the ligament has only gone from about 5.5 cm to about 6.0 cm: this means that there has not been much stress applied to the ligament even though we did apply a lot of stress to the combined structure of “muscles and deep connective tissues” (ie: even though we stretched both elastics, the more flexible elastic was the one that “took up the stress”.)
Let’s see how this would look if we did the same thing with “colder” muscles.
Hold one end of the ligament (ie: the white elastic) down at the zero point of your ruler. Loosely stretch the cool muscle (tan elastic) to the point where it naturally goes without putting any real stress on it. Note how long they both are. In the example shown here, they both take up about 14 centimeters, which is about the same as in the first example with the warm, but relaxed (unstretched) muscles. Now again, apply your stress to these tissues and stretch them until they are about 25 centimeters (~10 inches) long. Now, carefully note how long the ligament has become.
That is quite a change! In this picture the ligament has stretched to 8.5 cm compared to only 5.5 cm when the muscles was warmed up. Now, again, it is not that the ligament actually stretches, but rather that the stress applied to the whole system of tissues is distributed more equally to the connective tissues and the muscles if the muscles are cold. If the muslces are warm, they take the stretch…when they are cold, the stress can go deeper
Graphically then, this is why we want to do the yin practice while cooler if the objective of your practice is to obtain the physical benefits of Yin Yoga.
- — I am using the terms “stress” and “stretch” in a very technical way here. Stress is the tension that we place upon our tissues. Stretch is the elongation that results from the stress. We could be even more technical and drop the word “stretch” in favour of the more precise word “strain”, which is the ratio of the tissue’s length after and before a stress is applied, but that would risk getting a bit too pendantic. We often say we are stretching our muscles, but to be more precise, what we are doing is applying a stress to our muscles that results in a stretch. A stretch however does not always accompany a stress, so they are not the same thing. We can stress ligaments but, because the ligaments are more plastic and less elastic than the muscles, that stress will not result in a stretch. The key is the stress not the stretch.
- — There may be some small stretch to a ligament, however, generally the tendons and ligaments should not stretch more than 4 ~ 10% or we risk damaging them. See Michael Alter’s book, The Science of Flexibility
(Return to When to Practice Yin Yoga )