Stretching and Flexibility Defined
What is stretching? What is flexibility? And how do we define the different types of stretching and flexibility?
I like to read what other people write about stretching and flexibility, and for the most part I enjoy what I read. But one thing that bothers me is when people can’t even define what stretching or flexibility is, or worse still, when they define it incorrectly.
Unfortunately, the field of flexibility training has failed to progress in the same manner as strength training and other areas of athletic conditioning. I still hear arguments and debates about stretching that cause a lot of confusion and a great deal of misconceptions. And part of the confusion comes from the fact, that as an industry, the terms used in stretching and flexibility training have not been clearly defined.
To follow is an overview and definition of some of the common terms used as part of stretching and flexibility training. My hope is that this document will be constantly refined and updated, and used as a foundation or base-point for those looking to increase their knowledge on the subject of stretching and flexibility training. If you wish to contribute to this document please contact me with your suggestions.
First published: April 2007
Last updated: September 2014
What is Flexibility?
Flexibility is commonly described as the range of motion, or movement, around a particular joint or set of joints. Or in layman’s terms, how far we can reach, bend or turn. When improving flexibility is the goal, the muscles and their fascia (sheath) should be the major focus of flexibility training. While bones, joints, ligaments, tendons and skin do contribute to overall flexibility, we have limited control over these factors.
Two Types of Flexibility
Within the broader definition of flexibility there exists two distinct types of flexibility: Static and Dynamic.
The term static flexibility refers to an individual’s absolute range of motion that can be achieved without movement. In other words, how far we can reach, bend or turn and then hold that position. While the term dynamic flexibility refers to an individual’s absolute range of motion that can be achieved with movement. In other words, how far we can reach, bend or turn by using velocity to achieve maximum range of motion.
Static flexibility is sometimes referred to as passive flexibility, and dynamic flexibility is sometimes referred to as ballistic or functional flexibility.
Range of Motion (ROM)
Range of motion (ROM), or range of movement, is so intimately related to flexibility that the terms are often considered having the same meaning. That is, they all describe the extent to which a joint can go in its established spectrum of movements.
A joint’s normal range of motion is determined by what that joint does and how far the bones that comprise it can move. So, range of motion also measures the current amount of motion around a joint as determined by the condition of the bones and the soft tissue surrounding the joint that hold it together.
What is Stretching?
Stretching, as it relates to physical health and fitness, is the process of placing particular parts of the body into a position that will lengthen, or elongate, the muscles and associated soft tissues. Upon undertaking a regular stretching program a number of changes begin to occur within the body and specifically within the muscles themselves. Other tissues that begin to adapt to the stretching process include the fascia, tendons, ligaments, skin and scar tissue.
Two Types of Stretching
Although there are many different ways to perform a stretching exercise, they can all be grouped into one of two categories: Static or Dynamic.
The term static stretches refers to stretching exercises that are performed without movement. In other words, the individual gets into the stretch position and holds the stretch for a specific amount of time. While the term dynamic stretches refers to stretching exercises that are performed with movement. In other words, the individual uses a swinging or bouncing movement to extend their range of motion and flexibility.
Many Different Ways to Stretch
Just as there are many different ways to strength train, there are also many different ways to perform stretching exercises. However, it is important to note that although there are many different ways to stretch, no one way, or no one type of stretching is better than another. Each type has its own advantages and disadvantages, and the key to getting the most out of stretching lies in being able to match the right type of stretching to the purpose, or goal you are trying to achieve.
For example; PNF and passive stretching are great for creating permanent improvements in flexibility, but they are not very useful for warming up or preparing the body for activity. Dynamic stretching, on the other hand, is great for warming up but can be dangerous if used in the initial stages of injury rehabilitation.
Listed below are five different types of static stretching exercises.
- Static Stretching: Static stretching is performed by placing the body into a position whereby the muscle (or group of muscles) to be stretched is under tension. Both the antagonist, or opposing muscle group and the agonist, or muscles to be stretched are relaxed. Then slowly and cautiously the body is moved to increase the tension of the muscle (or group of muscles) being stretched. At this point the position is held or maintained to allow the muscles to lengthen. A minimum hold time of about 20 seconds is required for the muscles to relax and start to lengthen, while diminishing returns are experienced after 60 seconds. Static stretching is a very safe and effective form of stretching with a limited threat of injury. It is a good choice for beginners and sedentary individuals.
- Passive (or Assisted) Stretching: This form of stretching is very similar to static stretching; however another person or apparatus is used to help further stretch the muscles. Due to the greater force applied to the muscles, this form of stretching is slightly more hazardous. Therefore it is very important that any apparatus used is both solid and stable. When using a partner it is imperative that no jerky or bouncing force is applied to the stretched muscle. So, choose a partner carefully, the partner is responsible for the safety of the muscles and joints while performing the stretching exercises. Passive stretching is useful in helping to attain a greater range of movement, but carries with it a slightly higher risk of injury. It can also be used effectively as part of a rehabilitation program or as part of a cool down.
- Active Stretching: Active stretching is performed without any aid or assistance from an external force. This form of stretching involves using only the strength of the opposing muscles (antagonist) to generate a stretch within the targeted muscle group (agonist). The contraction of the opposing muscles helps to relax the stretched muscles. A classic example of an active stretch is one where an individual raises one leg straight out in front as high as possible and then maintains that position without any assistance from a partner or object. Active stretching is useful as a rehabilitation tool and a very effective form of conditioning before moving onto dynamic stretching exercises. This type of stretching exercise is usually quite difficult to hold and maintain for long periods of time and therefore the stretch position is usually only held for 10 to 15 seconds.
- PNF Stretching: PNF stretching, or Proprioceptive Neuromuscular Facilitation, is a more advanced form of flexibility training that involves both the stretching and contracting of the muscle group being targeted. PNF stretching was originally developed as a form of rehabilitation and for that function it is very effective. It is also excellent for targeting specific muscle groups, and as well as increasing flexibility, (and range of movement) it also improves muscular strength. There are many different variations of the PNF stretching principle and sometimes it is referred to as Contract-Relax stretching or Hold-Relax stretching. Post Isometric Relaxation (PIR) is another variation of the PNF technique. The area to be stretched is positioned so that the muscle (or muscle group) is under tension. The individual then contracts the stretched muscle group for 5 – 6 seconds while a partner (or immovable object) applies sufficient resistance to inhibit movement. The effort of contraction should be relevant to the level of conditioning. The contracted muscle group is then relaxed and a controlled stretch is applied for about 30 seconds. The athlete is then allowed 15 to 30 seconds to recover and the process is repeated 2 – 4 times.
- Isometric Stretching: Isometric stretching is a form of passive stretching similar to PNF stretching, but the contractions are held for a longer period of time. Isometric stretching places high demands on the stretched muscles and is not recommended for children or adolescents who are still growing. Other recommendations include allowing at least 48 hours rest between isometric stretching sessions and performing only one isometric stretching exercise per muscle group in a session. To perform an isometric stretch; assume the position of the passive stretch and then contract the stretched muscle for 10 to 15 seconds. Be sure that all movement of the limb is restricted. Then relax the muscle for at least 20 seconds. This procedure should be repeated two to five times.
Listed below are four different types of dynamic stretching exercises. Click here for a detailed explanation of dynamic stretching.
- Ballistic Stretching: Ballistic stretching is an outdated form of stretching that uses momentum generated by rapid swinging, bouncing and rebounding movements to force a body part past its normal range of movement. The risks associated with ballistic stretching far outweigh the gains, especially when better gains can be achieved by using other forms of stretching like dynamic stretching and PNF stretching. Other than potential injury, the main disadvantage of ballistic stretching is that it fails to allow the stretched muscle time to adapt to the stretched position and instead may cause the muscles to tighten up by repeatedly triggering the stretch reflex (or myotatic reflex).
- Dynamic Stretching: Unlike ballistic stretching, dynamic stretching uses a controlled, soft bounce or swinging motion to move a particular body part to the limit of its range of movement. The force of the bounce or swing is gradually increased but should never become radical or uncontrolled. Do not confuse dynamic stretching with ballistic stretching. Dynamic stretching is slow, gentle and very purposeful. At no time during dynamic stretching should a body part be forced past the joints normal range of movement. Ballistic stretching, on the other hand, is much more aggressive and its very purpose is to force the body part beyond the limit of its normal range of movement.
- Active Isolated (AI) Stretching: Active isolated (AI) stretching is a new form of stretching developed by Aaron L. Mattes. AI stretching is sometimes referred to as the Mattes Method. It works by contracting the antagonist, or opposing muscle group, which forces the stretched muscle group to relax. While AI stretching certainly has some benefits (mainly for the professional or well conditioned athlete), it also has a lot of unsubstantiated claims. One such claim is that AI stretching does not engage the stretch reflex because the stretch is only held for 2 seconds or less. This is nonsense and defies basic muscle physiology. The stretch reflex in the calf muscle for example is triggered within 3 hundredths of a second, so any claim that AI stretching can somehow bypass or outsmart the stretch reflex is nothing more than fantasy.
- Resistance Stretching and Loaded Stretching: Resistance stretching and loaded stretching are a form of dynamic stretching that both contract and lengthen a muscle at the same time. They work by stretching a muscle group through its entire range of motion while under contraction. For this reason, both resistance stretching and loaded stretching are as much about strengthening a muscle group as they are about stretching it. Like AI stretching above, resistance stretching and loaded stretching do have their benefits. Five time Olympic swimmer, Dara Torres credits a portion of her swimming success to the use of resistance stretching. However, these forms of stretching place high demands on the musculo-skeletal system and are therefore only recommended for professional or well conditioned athletes.
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About the Author: Brad is often referred to as the "Stretch Coach" and has even been called the Stretching Guru. Magazines such as Runners World, Bicycling, Triathlete, Swimming & Fitness, and Triathlon Sports have all featured his work. Amazon has listed his books on five Best-Seller lists. Google cites over 100,000 references to him and his work on the internet. And satisfied customers from 122 countries have sent 100's of testimonials. If you want to know about stretching, flexibility or sports injury management, Brad Walker is the go-to-guy.