Tired muscles can indeed be a pain in the neck, spine movement study shows
While fatigue in neck muscles has long been suspected of causing pain, the actual mechanical changes in the spine and muscles that precede weakness remain an outstanding question. Now, using high-precision X-ray imaging to track spine movements during neck exertion tasks, Texas A&M University researchers have discovered that sustained neck exertions cause muscle fatigue that then exaggerates the cervical spine curvature. This leads to neck pain.
Source: Medical Xpress