Stretching has been tooted for being the best thing since sliced bread for everything from injury prevention to increasing muscle tissue length and reducing stiffness. The latest research however would suggest that stretching does not in fact change tendon stiffness but may change muscle objective stiffness. It does however increase range of motion and passive resistance to torque ie. it takes more force to reach the new end of range point, but tissue stiffness does not change.
This is why ITB syndrome never made sense to me when I was starting out as a physio. If the mechanism for injury was friction over the lateral epicondyle for tight ITB and the fix was stretching the ITB or foam rolling, then why did it get better, worse or remain the same given that stretching does not in fact change fascia stiffness or length. There are some short term changes in the muscle tissue due to viscoelastic properties and other factors, but it usually returns to its original length. We cannot get to some new magical tissue length and maintain that length in the long term. Some studies argue that after long periods of stretching, you can actually lose heat in the unloading part of the exercise and this makes the tendon stiffer. Therefore there would appear to be no way to loosen connective tissue in the long run. This is a good thing in many ways as it could result in overly loosening our bodily structures which could have detrimental effects.
So... what happens when we stretch?
When we stretch, we increase our ability to tolerate stretch -ie the more we stretch into our end ranges, the more our body can tolerate it. This is a form of habituation. In other words, this is our nervous system allowing us to adapt to the new position. There may also be some changes in muscle morphology, where something in the joint becomes less stiff, perhaps even resulting in changes to the ligaments, but the tendon tissue appears to stay the same. In any case, these changes are generally short term but may be needed if your sport requires you to get itnto these end ranges of movement The more you stretch the more you are able to increase your range of motion (ROM) and the more force is needed to get to this new ROM. There may be some tissue changes but again, these changes are only temporary much like any intervention we do, stop strength training and you loose the gains pretty qucikly too So...when do we need to stretch? We stretch when we need to get into extreme ranges of movements like ballet dancers, perhaps some sprinters or anybody who needs to use these movements daily to improve their ROM which may improve their performance. If the activity you would like to engage in does not require you to get into these positions, I would suggest that then there is no need for stretching. Recent research shows that eccentric exercises have similar benefits to stretching, with the increased added value of more muscle strength, power and endurance. I would therefore argue that it is more valuable to strengthen and condition rather than stretch in many cases. Stretching is a form of resistance training as some research has shown that the muscle becomes more stiff after long periods of static stretching. The stiffer a tendon is the more power it can produce would be the theory.
It would appear some muscle changes occur resulting in temporary fascicle lengthening and neurological effects, habituation both occur to allow us to move further.
If this landed with you and you would like to work together to manage your pain and develop an effective rehab program, book a session with me @ www.skellyphysio.com
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