Stretching never actually changes muscle length.
It's been shown that the classic 30-45 second stretches hardly do anything for warm-ups or rehabbing injuries.
I know, "It feels good when I stretch" or "if I don't stretch I'll be stiff and sore for days".
The problem is that our muscles just contract and relax, and they have a predetermined maximal length.
When postural adaptations arise due to bone structure changes, ligament stiffness, and changes in fluid volume, our muscles will respond based on the positions that they are being leveraged in.
I shouldn't say never, but you would have to hold a stretch for a minimum of 5 minutes before you start to see a change in muscle length, which even then is minimal. Even more, the length you do gain will return to where it was pre stretch in about 2 minutes.
With more recent studies, it is determined that we build a tolerance to stretching, without actually changing the length. This may not be a great thing as it may decrease your recruitment ability of the muscle, which could lead to further injury.
The "feel good sensation" from the stretch is really just a relaxation effect, but this is not necessarily great for warm-ups as you want to recruit and muscle activity with rhythm and timing so you are prepared for increased intensity.
Sometimes extreme "tightness" is felt when we are at maximal length. The muscle is providing a braking force because it can't go any further. By decreasing this sensation you are neurologically turning off the brakes. Once you bypass this system, you are setting yourself up for muscle strains, pulls, and tears as the brakes can no longer stop you from pulling the muscles past their maximal length.
Using specific movement preparation exercises help you achieve positions that will change muscle behavior on joints. Learning new movement behaviors will allow you to perform at higher levels and keep tissues healthier vs just trying to pulling on a muscle in one position.
Start utilizing dynamic movements and activities that prepare you for your main workout to allow muscle tissue to be ready for higher intensities and achieve their full range of motion. Soreness with intense activity is inevitable, but that's a topic for another day. If you are sore, utilize your movement prep activities to loosen up vs the static stretches you have been doing.
If you still feel stuck, you can always email us at email@example.com and we will answer any questions you may have.
Dr. Peter Dionisopoulos is the owner and founder of Dynamic Performance & Rehab. He has a Doctorate in Physical Therapy and enjoys to help active adults maintain their lifestyle and provide natural solutions to their pain.