Stiffness or tension in the neck and shoulders; a condition causing heaviness or pain in the shoulder/neck area, often from prolonged posture or strain.
最近パソコン作業が多くて肩こりがひどい。
I've been doing a lot of computer work lately and my shoulders are really stiff.
毎朝起きると肩こりで首が回らないことがある。
Some mornings I wake up with such stiff shoulders that I can't turn my neck.
温めたりマッサージをすると肩こりが楽になることが多い。
Warming it or getting a massage often eases shoulder stiffness.