## 1 Introduction  
Low back pain (LBP) is one of the most common musculoskeletal disorders leading to disability. It is the main cause of activity limitations and absence from work worldwide [1; 2]. People who experience chronic and recurrent LBP have long-term disabilities, which result in a significant economic burden [3]. About 85% of the population complain of nonspecific low back pain at some point in their lives [4]. Pain, limited mobility, stiffness, or increased muscle tension below the costal margin and above the inferior gluteal folds, which may or may not convey pain to the leg, are collectively referred to as low back pain [4; 5]. LBP can be divided into specific and nonspecific LBP according to established etiology. The most common LBP is nonspecific, lacks a clear pathologic cause, and is not attributable to a recognizable, specific pathology such as fracture, ankylosing spondylitis, spondyloarthritis, infection, neoplasm, or metastasis [4; 5]. Chronic LBP occurs when symptoms persist beyond 12 weeks [4; 5; 6; 7]. Low back pain can be episodic for certain people, marked by remissions, relapses, and periodic flare-ups; this type of pain is referred to as persistent low back pain [7]. Research results have provided a variety of treatment options for LBP. Treatment options for LBP include acupuncture, educational tools, behavioral therapy, cognitive behavioral therapy, medication, Kinesiology tape, mechanical and manual traction, manual therapy, and exercise therapy [1; 6; 8; 9]. Strength-building, spinal stabilization, stretching, and aerobic and McKenzie method exercises are known to help patients with chronic LBP, and these exercise therapies have been shown to reduce pain and disability in the short and long term [7; 10; 11]. Research evidence does not indicate which type of exercise therapy is best for reducing LBP and improving functional ability [1]. For chronic LBP without serious pathology, the recommended primary conservative physical treatment options include exercise, yoga, biofeedback, progressive relaxation, massage, manual therapy, and interdisciplinary rehabilitation [7; 10; 11; 12]. Manual therapy (MT) involves treatment of the spine with the hands, including spinal manipulation and mobilization [13]. Both methods are equivalent and recommended as single interventions in guidelines [12]. Research evidence suggests that both mobilization and manipulation are safe methods [14]. MT is recommended in evidence-based clinical practice and other guidelines because of its use of non-pharmacological interventions for LBP [6; 12; 13; 15]. According to a systematic review of the literature, there is considerable evidence that manual therapy is no less effective than other treatments (exercise, conventional medical care, or physiotherapy) at reducing back pain and promoting healing [13; 16; 17]. One systematic review suggests sufficient evidence for MT's effectiveness in treating LBP [17; 18]. Another systematic review reported that MT is widely used in treating back pain. Several studies of different methodological quality and size were investigated, and mixed results were found [13]. Moreover, other studies found that treating LBP with MT showed no improvement [19]. There is still a lack of evidence regarding MT effectiveness, including manipulation and mobilization, with or without treatment, for pain or disability [14]. Thus, these studies do not clearly support the superiority of one type of intervention for treating chronic nonspecific LBP. Although the above treatments have been widely used, they show limited efficacy at best, with a recurrence rate of approximately 70% for LBP [9]. Despite a significant amount of scientific research in this area, there is still uncertainty about the most effective treatment. Thus, there are insufficient studies to demonstrate the greater or lesser effects of different therapeutic approaches in treating chronic nonspecific LBP.