When your neck muscles are tense and contracted then every other set of muscles will have to work harder. A free neck and well balanced head means you are able to release 'locked-in' tension in other parts of the body too, and gain more ease in every movement. It should be capable of movement as the needs of the athlete demand. In my techniques I often test this rigidity of an athlete. Many are quite incapable of turning their heads freely on their neck and shoulders.
Any rigidity here spreads right through the whole musculature.
Keep the head and neck free and the rest of the moving parts will tend to be free. A competitive Master's runner, Malcolm has completed five marathons and briefly held the Canadian sub-masters 1500 meter record. He is currently the Head Coach of the Cross Country and Track and Field programs at Concordia University.