There has been considerable public concern regarding the effects of repetitive head impacts associated with heading the ball in soccer. This is relevant for adolescents whose brains are undergoing rapid development. The study investigated the relationship between strength, proprioception, endurance and range of motion of the cervical spine and impacts associated with heading the ball in adolescent male soccer players. The participants were 20 skilled players aged 15-18 years. Outcome measures included questionnaires, assessments of cervical spine function (range of motion, joint position error, isometric muscle strength and endurance) and the ratio of maximum head acceleration to maximum T3 acceleration (impact ratio) during each ball impact when heading the ball. Results showed that increased range of motion of extension of the cervical spine and lower joint position error in flexion of the cervical spine were associated with higher impact ratios. Greater isometric strength of the lateral flexors was associated with lower impact ratios. Endurance of the deep neck flexors was not associated with impact ratios. Strength training may be beneficial to decrease head impacts during soccer ball heading, especially in those with increased range of motion of extension of the cervical spine.