## 1 Introduction  
Low back pain (LBP) represents a main reason for physician visits, hospitalization, or seeking other health care services [1]. In literature, the lifetime prevalence for LBP varies between 51-84%. LBP is not only common, but also holds a significant cost and health care utilization burden, as it is a leading cause of disability [2]. Chronic LBP is defined as back pain that persists for three or more months. In addition to persistent pain, many individuals often report sleep disturbances, depression, and high levels of fatigue [3, 4]. The underlying cause is often not easy to detect, often because mismatches between symptoms and diagnostic results (both clinical examination and imaging) is common [5]. Therefore, the optimal treatment choice is still challenging. However, in chronic back pain patients, a multidisciplinary approach combining medical, psychological, physical, and interventional therapies appear to be the most effective treatment, considering individual patient characteristics [6, 7, 8]. Pharmacologic treatments are common but associated with side effects and risk of medication abuse; for this reason, nonpharmacotic interventions are important in helping to reduce symptoms and disability [9]. Current evidence-based clinical guidelines propose exercise therapy as one of the few recommended treatments for chronic LBP [10]. Unfortunately, there is no evidence showing that one form of exercise is better than another; guidelines usually recommend exercise programs based on individual needs and capabilities. Regardless, the response to such treatment is not satisfactory in many patients, with only modest changes in pain and disability [10]. Even if the reasons for the widely varying individual response are largely unknown, one factor influencing individual success may be the adherence of the patient to the treatment. As conventional treatments often show only modest clinical effects, over the last years the utilization of alternative pain management methods is rising [11]. A subgroup of these therapies, the so called reflex therapies, acts mainly on the basis of reflex pathways via the spinal cord [12]. Among them, acquressure is a noninvasive, low-cost technique which was established and used in Traditional Chinese Medicine and makes use of physical pressure on specific points using a finger or a device [13]. Systematic reviews on acupressure support significant effects on chronic symptoms, such as pain and sleep disturbance [14]. Acupressure was also reported to positively modulate objective physiologic pain markers, such as proinflammatory and anti-inflammatory cytokines and neuropeptides [15]. A systematic review also demonstrated that the efficacy of treatment did not differ whether the acupressure was given by a therapist or self-administered, supporting its ease of use and low-cost [16]. Basing on acupressure principles, some authors proposed the use of a needle stimulation pad for patients with neck or back pain, but also for other conditions, such as headache, sleeping disorders, gastrointestinal diseases, or just for relaxation [17; 18]. This device is usually composed of sharp but nonpenetrating plastic needles and the patient lies on it with the painful part of the body. The precise mechanism of action of a needle stimulation mat is not clear but probably depends on different aspects. Mechanical skin stimulation increases local blood microcirculation and tissue metabolism processes by actively supplying oxygen and removing carbon dioxide, thus reducing the concentrations of inflammatory cytokines [19]. The mechanical stimulation of skin, subcutaneous tissue, and muscles is similar to that obtained with other complementary and alternative medicine manual and physical therapies (for example, gua sha massage and wet cupping). Such stimulation likely activates skin mechanoreceptors and even nociceptors, thus affecting the transmission and processing of sensory information to a spinal and supraspinal level [12].