Even though the incident was momentary, the memory persisted, and along with it, the protective, reflexive reaction. Suddenly a tension habit was formed. Within minutes, in many cases of whiplash injury, neck muscles are fatigued and sore. That soreness, felt as neck pain, may have convinced you that you were injured, leading you to guard against head movement to prevent further pain. Guarding leads to further tension, tension leads to pain, and pain leads to a diagnosis of a whiplash injury.
Tension also leads to muscle fatigue, and muscle fatigue feels like muscle weakness.
As incidents of injury usually come from one side or the other, muscles are affected unequally. Loss of spinal alignment leads to distorted head movement and to unbalanced head position. The combination of distorted head movement and unbalanced head position send distorted sensations from the balance centers of the inner ears to the balance centers of the brain. The same muscular tension also pulls the vertebrae of your neck closer together, making your neck shorter, thicker, and stiffer. Pressure on the discs increases, sometimes leading to disc degeneration and sometimes, to pinched nerves, with pain and numbness down the arms, possibly into the hands.