Comparative Study on SNAG From Loaded and Unloaded Position in the Treatment of Low Back Pain

Low back pain (LBP) is a global health problem with an estimated lifetime prevalence of up to 80% in adults [1]. It is one of the leading causes of disability worldwide and places a substantial burden on health care systems and economies. Although most cases are nonspecific, patients often experience significant pain, restricted mobility, and impaired function, which negatively affect their quality of life [2].

The global burden of low back pain remains substantial, particularly among middle-aged adults (45-59 years), with a disability-adjusted life years rate of 747.92 per 100,000 population in 2021. Notably, high body mass index was the only risk factor showing a significant increasing trend (estimated annual percentage change = 1.08) over the past three decades [3]. This epidemiological context underscores the clinical importance of our comparison, as loaded SNAGs may be particularly relevant for overweight/obese patients who experience greater gravitational loading on the lumbar spine during daily activities Management strategies typically involve a combination of exercise, patient education, and manual therapy [3]. Among manual therapy approaches, the Mulligan Concept - specifically, Sustained Natural Apophyseal Glides (SNAGs) - has gained attention due to its reported immediate effects on pain reduction and mobility.

SNAGs are a form of Mulligan concept mobilization-with-movement in which the therapist applies a sustained accessory glide to a spinal segment. At the same time, the patient actively performs the symptomatic movement. Evidence suggests SNAGs can improve pain, lumbar range of motion (ROM), and functional status in patients diagnosed with nonspecific LBP [4-6].

A central principle of SNAGs is their application in functional, weight-bearing positions that reflect real-life movement demands. However, physiotherapists sometimes apply SNAGs in unloaded positions (e.g., prone or quadruped) in both clinical settings and research situations. 9,10 Biomechanical research demonstrates that spinal loading alters facet joint kinematics and tissue stresses, suggesting that the clinical effect of SNAGs may depend on whether they are applied in a loaded or unloaded position [7, 8]. Despite this, no randomised controlled trials (RCTs) have directly compared these two SNAG modes.

This study aims to address this gap by comparing the clinical effectiveness of lumbar SNAGs applied in loaded versus unloaded positions on pain, ROM, and function in patients with chronic nonspecific LBP.