Intra-rater reliability ranged from moderate to almost perfect agreement for joint position error ( ICC@-@ @ ) , the cranio-cervical flexion test ( ICC@ @ ) , the neck flexor muscle endurance test performed in supine ( ICC@ @ ) and in a @-upright position ( ICC@ @ ) with the exception of a new test ( neck extensor test ) , which ranged from slight to moderate agreement ( ICC = @-@ @ ) .