Published: 2007-08-21 23:21:17
Last edit: 2007-08-21 04:02:19
Tags: flexibility joint rom stretching
Your body's movement is predicated on the right muscle activating at the right time; so, it's not surprising that flexibility training is important. After all, if a joint isn’t able to move through a full range of motion (ROM) it’s at a biomechanical disadvantage due to the length-tension principle or in other words a muscle needs to be able to fully contract for optimal strength. If a muscle imbalance precludes proper ROM at a joint it will force other muscles to compensate for its inefficiency; essentially, setting you up for a "movement pattern overload" type of injury.
In general terms a muscle may become short (overactive) or a muscle may become long (under-active) and a muscle that’s chronically shortened will be weak when lengthened and a muscle that's chronically lengthened will be weak when shortening. In many instances it's impossible to know to if the short or lengthened muscle is the primary problem. The most practical solution for “a general flexibility routine” encompasses stretching the tight muscle, activating the lengthened muscle (contract the antagonist or opposite muscle group you're stretching), and integrating it all with good balance and posture (that will be another article :-)
Types of Stretching:
In general terms, and to avoid getting caught up in the stretching controversy, there are two types of stretching: static (without motion) and dynamic (with motion). Yes, there are dozens of different stretching names, but they are mostly derivative of the basic ones we'll cover. As per usual it’s up to YOU to decide what’s needed for your lifestyle.
Static stretching consists of stretching a muscle as far as possible without pain and then holding that position for 20-30 seconds. This form of relaxed stretching is used to increase flexibility over a long period of time (as in months, not the hold of the stretch), during cool downs to prevent blood pooling and return the muscle to it's resting position, plus as a measure to relieve spasms and prevent adhesions in muscles that are healing after an injury. The term passive stretching is very similar and the main difference is the use of external force (either a stretching buddy or an exercise apparatus) brings the joint through its range of motion.
Proprioceptive Neuromuscular Facilitation (PNF) is a wide assortment of rehabilitative movements used to re-educate a muscle; however, we'll only touch upon the stretching aspect. The contract-relax technique take advantage of the post isometric relaxation in a muscle to increase its range of motion; for those interested it's occurs when the Golgi Tendons Organs/GTO sense tension overload and relax a muscle to prevent injury. After assuming an initial passive stretch, the muscle being stretched is isometrically contracted for 5-10 seconds, after which the muscle is briefly relaxed for 2-3 seconds (GTO causes relaxation), and then immediately subjected to a passive stretch which stretches the muscle even further than the initial passive stretch. This final passive stretch is held for 10-15 seconds (this whole process is to "trick" the muscle spindle fibers that contract a muscle when it's stretched too far, too fast). The method can also include contracting the antagonist muscle before going deeper into the stretch. For example, stretch your hamstring, isometric contraction of hamstring, isometric contraction of the quads, and then deeper into the stretch.
Dynamic stretching consists of controlled leg and arm swings that take you to the limits of your range of motion and not beyond as in ballistic stretching. An example of dynamic stretching would be slow, controlled leg swings, arm swings, or torso twists as part of a warm-up for an activity. Your proprioception is allowed to keep track of these controlled movement by providing feedback to the central nervous system (CNS).
Ballistic stretching uses momentum rather than muscular control to increase ROM and allows for bouncing. This form of stretching uses the momentum of a moving body or a limb in an attempt to force it beyond its normal range of motion and is obviously used with discretion. Your proprioception loses track of such "uncontrolled" movements and there is no feedback to the CNS to alter the outcome of the stretch.
Important note: There is a situation where neural tightness can make a muscle feel tight and the loss of range of motion is from an overactive nervous system (you are stressed out!) and not structural limitations. For instance, it's common for people to have the sensation of tight hamstring even though the muscle is already in a lengthened state (see the case study for more information).
Todd Langer, MSc.