What is a muscle stretching?
Stretching is form of exercise which lengthens your tight muscle and allow your joint to have better range.
Is stretching helpful?
Yes, for those who have tight muscle which is preventing you from moving throughout whole range of certain joint
BUT, stretching doesn't apply in every case!
Muscle pain can also occur from your muscle being in stretched position. For example, if you neck or shoulder protracts forward, your upper trapezius muscle can get stretched and stay in lengthened position. This will create tension on your neck/shoulder region.
When your muscle is in stress due to being stretched, we need to help your muscle to return back (shorter) to its original length by performing exercise (e.g. shoulder retraction / shoulder shrug exercises).
We need to choose when to stretch our muscle, and if you have been feeling more pain or stretching not relieving your symptom, you might want to question yourself about stretching you have been performing. Geez, nothing is so simple.