Stress and Muscle Tone
Most people have had the experience of being told to relax their shoulders and realising just how much tension they had been carrying. This can be caused as part of the fight or flight response to stress. Muscle tone will tend to increase under stress, however not all muscles respond the same. Larger global muscles such as the muscles of the hips, back of legs and neck will tend to be most effected. Joint health relies on finely balanced muscle co-ordination and when disrupted this could disrupt joint function predisposing to both acute and chronic injury. Similarly, increased muscle tone increases compressive forces in joints, which at a threshold level may further contribute to symptoms.
Smooth muscles cells like those in arteries are located in the collagen within ligaments, intervertebral discs and menisci. These respond to stress by contracting, as do the smooth muscle cells in arteries, which lead to high blood pressure under periods of stress. From an evolutionary perspective this increased tightness may have helped us be more biomechanically stable in fight or flight situations. However, as part of a chronic stress response this can contribute to the superficial tightness commonly seen in the clinic in patients with stress related musculoskeletal pain.
Citations available on request