The effects of cervical sustained natural apophyseal glides on neck range of movement and sympathetic nervous system activity

Abstract Background Cervical sustained natural apophyseal glides (SNAGs) have been advocated for the treatment of spinal pain and range of movement restriction, however little is known about their mechanisms of action. Knowledge about their mechanisms should help understand the factors that influence the effectiveness of this technique. Objectives To study the immediate effects of SNAGs on neck range of movement (ROM) and sympathetic nervous system activity. To assess if a difference exists in the effects of ipsilateral and contralateral cervical SNAGs. Design Single blind, intervention randomised, within subject crossover. Method 30 asymptomatic subjects were recruited. Subjects were divided into an ipsilateral or contralateral SNAGs group. All subjects experienced a right C5 SNAGs, sham and control intervention on three separate days. Neck ROM, skin conduction (SC) and skin temperature (ST) in the right hand were measured. Results Right rotation ROM and SC increased following both SNAGs and sham interventions, with increases reaching statistical significance for ROM in the contralateral SNAGs group and for SC in the ipsilateral SNAGs group. No statistically significant differences were noted between ipsilateral or contralateral SNAGs and sham interventions. No significant changes in ST were noted. Conclusion C5 cervical right rotation SNAGs resulted in improved right rotation ROM and increased SC, however such effect was not greater than sham intervention. No effect was noted on ST. Further research is required to study the mechanism of action of SNAGs on symptomatic participants.