Low back pain and the attendant disabilities have been on the increase in Africa and its burden is more in countries with longer life expectancy . The menace of the condition includes high level of disability, producing significant restrictions on usual activity and participation, such as ability to work . Contrary to general belief, LBP is not a problem that always resolves by itself, recurrences are usual and the course is varying in different circumstances . While emerging evidence and advocacy by Physiotherapy Associations favours active treatment for long-term LBP, however, spinal manipulation remains an important option for LBP that will or not resolve with active and self-care. Spinal manipulation has been reported to produce significant benefits within a short period , may be more and faster than expected improvements with active therapies . Further, while there is increasing advocacy for active management of LBP, many patients are not well suited or positioned to treat themselves, hence may require experts' management.

Sustained Natural Apophyseal Glide (SNAGS) is a manipulative technique that is commonly used in the western countries and found to be effective in reducing pain and disability in the management of mechanical LBP . In another study by Shabana et al., on the comparative effect of SNAGS and Maitland's mobilization in chronic LBP, better improvement was observed in SNAGS group than in Maitland's. however, it is not commonly used in the Nigerian context. On the other hand, the Nwugarian technique; VOP, propunded by Nwuga is a home-grown spinal manipulation approach in Nigeria demonstrated the effectiveness of VOP on pain and disability in patients with mechanical lowback pain. VOP, in combination with lumbar stabilization exercises has also been noted to be more effective compared with VOP in isolation in the management chronic low back pain . Similarly, Egwu et al., concluded that VOP has significant effects on pain intensity and Lumbo-sacral mobility, and opined that VOP should be preferred as spinal mobilization therapy outcome measures in youths and elderly individuals with LBP. The effectiveness of VOP is hinged on few available studies. VOP requires pressure on the vertebral spinous process with oscillation by the therapist. The therapeutic mechanism of spinal manipulation have emphasized the importance of directing forces to specific spinal joints for the purpose of correcting a biomechanical dysfunction or misalignment . Studies have also shown and validated spinal manipulation to affect both sensory and motor nerve activity as well as electromyographic measured muscle activity . Outcome measures reflect the impact of the health care service or intervention on the health status of patients. To achieve comprehensive multidimensional evaluation of outcome in LBP ,one of the core outcome domains that must be considered is pain, the method of assessing has always been participants rating of improvement and satisfaction with treatment but not the effects of intervention at cellular level. Use of serum biomarkers has the potential to measure the effects of intervention at cellular level thereby helping to identify relevant treatment options and decrease the likelihood of failed interventions. However, effects of known treatment like VOP and SNAGS on the inflammatory status and bio cellular pain substance in patients with long term low-back pain has not been explored, ,hence this study This study is therefore aimed to investigate and compare the effect of VOP and SNAGS on pain-biomarkers, disability, flexibility and health-related quality of life in patients with mechanical LBP.