Stretching - The Basics! Part 1

Magnus Agren
www.magnusagren.com

There is and will always be different opinions about the importance of stretching, and the benefits of it! But anyone who has spent some time in the fitness and sports industry knows its value. In this two part article series I will cover the stretching basics. In this first one will focus on the “technical” pieces while the second will be more about the “practical“ parts.

Most people tend to see ordinary stretching and flexibility training as one and the same, and far too many do not pay enough attention to this part of their training either, which is a BIG mistake! Almost everyone starting out, it may be the beginner just getting into strength training or the seasoned veteran starting over again after some time away, should pay ample amount of time with it in order to be able to perform their strength training exercises in proper form. Many simply do not have the flexibility and/or correct relationships of muscle length to do the lifting exercises as they should be done. I get to see this time after time. It is NOT the range of motion in one SINGLE muscle that is of interest here, it is the RELATIONSHIP BETWEEN muscles around a joint that is important. Each and every muscle in a joint NEED to be at “normal” length, so you can perform the movement around the joint as it was designed and not to put stress on the wrong structures! So the first thing to do and concentrate on is length balancing between the muscles around the joints! It does not matter if you increase the range of movement in your pectorals, chest muscle, if other muscles around the shoulder joint are off the chart, so to speak. Yes you may get a greater range of movement in your chest press exercise, but that may also stress your shoulder joint in a bad way and result in injury to it or its surrounding muscles!

So I thought I should sort things out a bit, give you an introduction and my two cents on how to integrate stretching in your daily training. I will focus on the most common types of stretching and try to explain the “best” use of them. But first let us have a look at some of the benefits you might enjoy by adding a serious and effective flexibility part to your training. I guess fellow tribe member Julien has done his fair share… And let us at the same time look at what exactly happens when you stretch a muscle.

Some benefits in no particular order:

1. Increased range of motion

2. Decreased recovery time

3. Lower risk of injury

4. Improved performance

5. Better posture

6. Less neck and lower back pain and problems

7. Better joint health

8. Less energy cost to the body

What happens?

The stretching of a muscle fiber begins with the sarcomere, the basic unit of contraction in the muscle fiber. When a sarcomere contracts the area of overlap between the thick and thin myofilaments increases. As it stretches, this area of overlap decreases, allowing the muscle fiber to elongate. Once the muscle fiber is at its maximum resting length, this is when all the sarcomeres are fully stretched, additional stretching puts force on the surrounding connective tissue. As the tension increases, the collagen fibers in the connective tissue align themselves along the same line of force as the tension. So when you stretch, the muscle fiber is pulled out to its full length sarcomere by sarcomere, and then the connective tissue takes up the remaining slack. When this occurs, any disorganized fibers are realigned in the direction of the tension. This realignment is what helps to rehabilitate scarred tissue back to health.

When a muscle is being stretched, some of its fibers lengthen, but other fibers may remain at rest. The current length of the entire muscle depends upon the number of stretched fibers. The more fibers that are stretched, the greater the length of the stretched muscle will be.

The nerve endings that send all the information about the musculoskeletal system to the brain are called proprioceptors. Proprioceptors inform the brain about the body position and its movements. They detect any changes in physical position, movement or displacement and any alteration in tension, or force, within the body. They are found in all nerve endings in joints, muscles and tendons, the proprioceptors related to stretching are located in the tendons and in the muscle fibers. So when you stretch your muscles, the body must adapt to this new position of location.

There are two kinds of muscle fibers- the intrafusal and the extrafusal muscle fibers. Extrafusal fibers contain myofibrils and are the ones we usually refer to when talking about muscle fibers. The intrafusal fibers, also called muscle spindles, lie parallel to the extrafusal fibers. These are the primary proprioceptors in the muscle. Another proprioceptor involved during stretching is located in the tendon near the end of the muscle fiber and is called the Golgi tendon organ. There is also a third type of proprioceptor, called the Pacinian corpuscle, it is located close to the Golgi tendon organ and is responsible for detecting changes in movement and pressure within the body. As stated earlier each of these three will be subjected to some kind of “disturbance” during stretching - as the extrafusal fibers of a muscle lengthen so do the intrafusal fibers.

The muscle spindle contains two different types of fibers, or stretch receptors, which are sensitive to changes in muscle length and the rate of the change. During a muscle contraction a tension change occurs in the tendon where the Golgi tendon organ is located. The Golgi tendon organ is sensitive to such changes and the rate of them, so these factors will affect your stretches in different ways. Read on…

The Stretch Reflex

When a muscle is stretched the muscle spindle records the change in length, and the rate of such, and sends signals to the spinal cord, which conveys this information. This triggers the stretch reflex, attempting to resist the change in muscle length by making the stretched muscle contract. The more sudden the change in muscle length, the stronger the reactive muscle contractions will be- plyometric, or "jump" training is based on this fact. This basic function of the muscle spindle is to help maintain the muscle tone and protect the body from injury. But this can also be an obstacle during stretching if done wrong. Therefore it is very important not to force your self or to do any hasty movements while stretching. One of the reasons for holding the stretch for a prolonged period of time is that as you hold the muscle in a stretched position the muscle spindle becomes accustomed to the new length and reduces its signaling. Gradually, you can train your stretch receptors to allow greater lengthening of the muscles.

So now back to the different kinds of stretching:

1. Ordinary Static Stretching - The most common type of stretching is where you hold a muscle stretched in a fixed position for about 30-60 seconds and thereafter slowly ease out of it. This is a great variation to use after workout or during the day to get your muscles elongated, or to keep them in their current state. I would suggest you do each stretch 2-3 times for best results.

2. PNF (proprioceptive neuromuscular facilitation) is often a combination of passive stretching and isometrics contractions. The use of contractions will trick the body into letting you go into a deeper stretch (see the different mechanisms above) and this is a very useful method for developing flexibility in a smaller time frame. As a trainer and therapist this is the way I stretch my clients most of the time. There are a lot of different PNF methods out there; here are some frequently used.
1. Hold-Relax are the most common method. You fire the tight muscle either against a fixed object or your partners hand for about 10-20 seconds. Then you relax and lightly stretch out the muscle to a new position and hold it there, repeating the procedure another 2-3 times.
2. Antagonist Contraction you passively lengthen the tight muscle to it end-range. Then you concentrically contract the muscle opposite to the tight muscle, the antagonist that is, to reach a new end range. This technique incorporates reciprocal inhibition - when one muscle contracts its antagonist relaxes.
3. Hold-Relax with Antagonist Contraction is in my opinion the best and fastest way to increase the range of movement in a single muscle by using a combination of the two methods described above. When you relax your tight muscle you will at the same time contract its antagonist.

These static stretches with prolonged holding positions are usually done in warm-ups, which isn´t all wrong - please read my warm - up article about this subject! But here the length monitoring cells in the muscle are stretched without the brain being able to monitor the actual change in length. So what happens in this case is that when you move out of this new position the information to the brain does not match the information already stored there for the “standard” movement, whereby the brain tries to figure out how to modulate the new movement to match the stored information. This can affect you in such a way that when you do an exercise your mind automatically miscalculates the information sent to it, as your regular and safe standard no longer matches your brains standard, which elevates the potential risk of getting injured from that exercise. This is more pronounced when doing fast ballistic movements. But of course there are exceptions to this rule, too, of not doing static stretching during warm up, which I will come back to this later on in the article.
I would suggest you use this kind of stretching primarily in rehab, after workouts or in separate sessions for increased flexibility and joint health and integrity.
Stretching directly after a work out may enhance recovery due to increased circulation etc., but I would not use it as the primary way to increase length in a muscle. After a work out the nervous system is at work for some time and it will negate the stretching effect. So if your goal is muscle length and flexibility then you do best separating it from any nervous system teasing training!
Words of caution though, never force your self into a stretch or perform it too quickly. A stretch should never hurt, it can be more or less painful but it should not hurt!!

3. Dynamic Stretching was also mentioned in my warm-up article, but here´s a quick recap. This method of stretching is based on larger movements done in increasing range of motion. You should do it in slow continuous movements. When you keep moving your brain constantly monitors the change in length of the muscle and makes the necessary adjustments accordingly

This kind of stretch is the one that I would suggest for warm-ups, but as I wrote earlier there are exceptions to the rule. I touched a bit on this in the warm-up article, but left out some information that I will share with you now.

But first let’s recap:

You use static stretches mainly to elongate specific muscles and use them in preventive, rehabilitating and restoration purposes. Dynamic stretches are primarily used as part of the warm-up to increase range of motion in a brain-friendly way, so to speak.

On to the exception now!

There are three types of muscles and they do not all respond to stretching the same way. A muscle in the body is comprised of both fast twitch and slow twitch muscle fibers. Fast twitch are best suited for power and speed, whereas slow twitch are used more in prolonged work situations. Your postural muscles are predominantly slow twitch, also referred to as tonic muscles. Your fast twitch dominant muscles are also referred to as phasic muscles. The third type is composed of fairly equal parts slow and fast fibers, so these muscles don’t fall into either the tonic or phasic group.

The interesting part is that the tonic muscles react to faulty loading situations in a very different way than do phasic muscles. When overworked to elicit a response your tonic muscles will elongate and weaken, while the phasic muscles shorten and tighten. But that is not all! The tonic muscles will also become more and more excited and try to do the work for the related phasic muscles. This is very important information, because a short tonic muscle will rob nerve energy from other important muscles and alter your biomechanics! So you could, and sometimes should, implement stretching of the tonic muscles in your warm-up, but best done in conjunction with dynamic to get the brain and body to work as a whole.

Here is an overview of common tonic muscles for you to see which muscles might be in need of stretching before a work out:

Muscle with tendencies to be short/tonic

Upper Trapezius

Levator Scapulae

Short Cervical Extensors

Pectoralis Major

Pectoralis Minor

Erector Spinae

Psoas

Rectus Femoris

Piriformis

Short and long Adductors

Gastrocnemius

I hope you got a bit of insight on stretching through this article, on what happens, what to choose and when, since stretching may be one of the more important tools, if not The most important tool - to help balance and align the body and its biomechanics.

So let’s now make time for some serious and well-planned stretching. In the next installment of this article series I will let you in on how to do the, in my opinion, best stretches, for you to reap the benefits you would like and could expect of stretching - not just going through the movements “for the good cause”, or worse, stretch the wrong muscles!

To be continued…