Many people put a lot of stock into stretching and blame injury on lack of stretching or not being flexible. Ironically, I have found that a fair number of clients have actually injured themselves by over stretching. When I get into the details of how they were stretching, it is clear that they are not quite stretching just the muscle. The techniques many people use sometimes might be the worst thing they can do.
Generally speaking, when most people think of stretching they are referring to muscle stretching. Muscle stretching is defined as lengthening of the muscle fibers from the origin to the insertion. All muscles have an “origin attachment” on a bone and an “insertion attachment” on a different bone and will cross at least one joint. So, when the muscle fibers contract, then a shortening effect is initiated and that creates the movement at the associated joint. It stands to reason, that when we stretch we are just doing the opposite. So, both the origin and the insertion points of that muscle are spread apart across the associated joint causing a lengthening of that muscle. To that effect, if either, or both the origin and insertion points are not stabilized then the muscle stretching may not be appropriately effective to just the muscle.
For example, the hamstring, is a muscle that is often stretched with poor stabilization. To safely and correctly stretch the hamstring the pelvis should be rotated forward, not backward. In the pictures below from Olaf Evjenth’s Autostretching text we see in the picture on the right that the pelvis is rotated backward. This is a very common stretch that I see done. Unfortunately, when the pelvis is rotated backwards, then the stretch loses its effectiveness on the hamstring and places an abnormal flexion load through the lumbar spine. That might not be so bad some might say, “to also stretch the joints in the low back.” Actually, stretching the joints of the low back is not good. The joints in the low back tend to develop hyper-mobility and when that happens, they should not be stretched. By stretching the joints in the low back that could lead to increased joint instability and chronic low-back pain.
Moreover, to effectively isolate a muscle that really means that you are trying to minimize the lengthening effects of the adjacent anatomical structures that may not be appropriate to stretch. Let’s look at the hamstring example again. In the picture above on the left, you can see how the pelvis is rotated forward. Such a rotation of the pelvis forces the pelvic hamstring attachment further away from the knee attachment. This creates a stabilization of the pelvis and prevents undesirable “lengthening forces” to the ligaments in the low-back.
Furthermore, regarding this hamstring example, patients will sometimes tell me they feel the stretch in the low back, behind the knee, or sometimes they will say they feel some sensation or pulling in the calf. If the hamstring is in the back of the thigh, then you should feel the stretch in that appropriate area, the back of the thigh. Therefore, if you feel the stretch elsewhere, then something about the stretch set-up and technique is improper and most likely means the origin and insertion points ae not properly stabilized.
Proper muscle stretching is important for many reasons. Properly warming up before sports or exercise is perhaps a critical time, but be careful not to overstretch in that situation. Because you can predispose yourself to strain. Many times, athletes are too vigorous and are not stabilizing surrounding structures with stretching prior to sports events and that is what leads to strain. How many times have you heard of professional players injuring themselves in warm up?
It is wise to start with light calisthenics before muscle stretching to get the blood flowing through the muscle, then to work into light to moderate stretching of the major muscle groups. Major muscle groups in the lower extremity might include the hamstrings, glutes, hip flexors and calf muscles.
When muscle stretching is not isolated at the muscle, we may see injury. The collateral damage are the ligaments, joints and other soft tissues that gets stretched. Ligaments and joints don’t like stretch. Their design is to stabilize and limit movement, so when they get excessively lengthened that can cause instability and potential injury. Granted one improper stretch is not going to cause a strain, but repeatedly over time the stretching of the ligaments through improper stretching will eventually lead to lengthening of those ligaments and instability. Then, that will cause injury to the adjacent soft tissues such as the lumbar discs, which potentially could be the case in our hamstring example above. If you have questions about the way you are stretching, or you are not quite sure that you know how to stretch correctly, then contact a fellowship trained physical therapist.
Evjenth, O and Hamberg, J. (1997). Auto Stretching The Complete Manual of Specific Stretching. Alfta Rehab Forlag, Alfta Sweden.