Stretching
We stretch muscles because they are too short and we want to lengthen them. This shortness could be looked at as either structural, lesions in the connective tissue bind up the muscle, or functional, excessive activity from the nervous system creates too many active motor units. In reality of course there is generally a combination of both and the two affect each other but for now it's sufficient to know that we're trying to overcome one or both of these limitations. The studies of connective tissue and proprioception respectively (coming soon) will give you more information about how this happens.
The nervous system is a quick acting regulator, this means that if we do an exercise and immediately notice a change in muscle length it's been through the immediate action of the nervous system. Changes in connective tissue length will take much longer.
Stretching the connective tissue
As we've already seen the collagen fibres in the myofascia tend to be arranged in the direction of the force applied to them. When localised adhesions in the connective tissue, through scarring or overuse, cause matting of the fibers, the capacity of the muscle to stretch out is reduced. Prolonged tension in one direction, such as that produced during stretching, will encourage new collagen fibres to follow the direction of the stretch.
Reprogramming the nervous system
A quick stretch will create a myotatic (or stretch) reflex that causes the muscle to contract. Slow prolonged stretching is thought to override the myotatic reflex and eventually reprogram it to allow for a lower level of motor activity in the muscle. Some stretching techniques, such as the active techniques described later on, take advantage of the neuromuscular interactions to increase muscle length.
Stretching Safely
Stretching is obviously a good thing to do but it can do more harm than good if not done properly.
- Always warm up before stretching. Any physical activity that involves movement will get blood into the muscles will usually do as a warm up, the Dao Yin exercises in the program are excellent. Don't confuse warm ups and stretches, a stretch is meant to lengthen short muscles and needs to be held for a minimum of 30 to 45 seconds, many warm ups may look like stretches because they take a joint close to the end of it's range of movement but they don't lengthen shortened myofascia.
- Move into your stretch slowly, from a stable position and only go as far as feels comfortable. After a while you may feel like you can push it a little further that's OK. It's OK to feel a strong stretch but not straight away, ease yourself into it.
- Stretching involves taking joints to the end of their range of movement, if a joint is compromised then this will hurt. If you feel pain stop immediately, if it persists then see a health professional.
Passive Stretching
Passive stretching depends on the energy of other muscles to generate tension in both the muscle and connective tissue fibres. It is important that the direction of the force creating this tension is as close to possible to the line of the muscle, between the distal and proximal tendons
In this stretch I'm using the muscles in my left arm to pull my right elbow back. This creates a passive tension in the tricep muscle along the line indicated by the white arrow and in the lateral shoulder rotators (green arrow). This direction is important because collagen fibres are embedded into the connective tissue according to the forces that are applied to it and we want this direction to be consistent with the direction of the muscle fibres.