Body Composition and Cervical Outcomes in Non-Specific Neck Pain

Non-specific neck pain (NSNP) is defined as pain located in the posterior and lateral regions of the neck between the superior nuchal line and the first thoracic vertebra, in the absence of neurological or specific pathologies such as fracture, infection, or inflammation. Neck pain is a common and widespread condition with an episodic course that affects a large proportion of the population. It has been reported that at least 80% of individuals experience neck pain and related disorders at some point during their lifetime. Moreover, 30-50% of the general adult population report experiencing neck pain at least once per year. In addition, approximately 25% of outpatient visits to Physical Medicine and Rehabilitation clinics are due to neck pain complaints. For the majority of patients, neck pain is a complex biopsychosocial disorder accompanied by both physical and psychological symptoms. A relationship between the severity of neck pain and disability has been reported, and neck pain has been associated with decreased health-related quality of life, reduced work productivity, limitations in daily activities, and increased utilization of healthcare services. Risk factors for NSNP include prolonged and/or improper computer use, non-ergonomic desk and chair use, physical activity level, poor posture, body mass index (BMI), female sex, longer working hours, fewer hours of sleep, and stress. Body composition refers to the different tissues that make up total body mass, generally expressed as muscle, fat, bone, and residual mass. Analyses of muscle and fat tissues have shown that muscle cells consist of approximately 70% water, 7% fat, and 22% protein. An excess of fat cells in the body exerts an inhibitory effect on muscles, limiting their ability to function effectively and consequently restricting movement. Additionally, in physical fitness assessments, body composition is often evaluated by examining fat mass and fat-free mass. The literature reports that the load applied to the cervical spine is approximately 10-12 lbs when the head is in a neutral position, increasing to 60 lbs when the head is flexed to 60 degrees. Prolonged maintenance of a forward head position results in irritation of the facet joints, ligaments, and soft tissues of the cervical region. This irritation may cause neck pain radiating to the shoulders and upper back. Furthermore, sustained forward head posture may lead to trigger point formation in muscles, joint motion restrictions, disc degeneration, and potential pathologies such as cervical degenerative disc disease, cervical osteoarthritis, or cervical disc herniation. Maintaining proper posture has been identified as an important factor in the management of neck pain.

Chronic neck pain is a multifactorial condition associated not only with various dysfunctions in the cervical region but also with related structures in other parts of the body. In individuals with chronic neck pain, decreased muscle strength and endurance, limitations in joint range of motion, altered muscle activation patterns, forward head posture, impaired proprioception, and psychological dysfunctions have been reported. In chronic neck pain, a reduction in joint position sense and imbalance in the axio-scapular muscles lead to a shift in the body's midline. An anterior shift of the midline results in abnormal postural patterns, primarily forward head posture. This condition contributes to the development of upper crossed syndrome, which encompasses a range of postural impairments including shoulder elevation and protraction, upper thoracic kyphosis (dowager's hump), scapular winging, and reduced thoracic mobility.

Individuals with neck pain may present with movement restrictions, pain, decreased cervical and thoracic segmental mobility, myotomal muscle weakness, postural abnormalities, numbness or paresthesia, reduced muscle flexibility, increased muscle tension accompanied by a predisposition to myofascial trigger point formation, decreased proprioception, reduced endurance of neck muscles, and impaired coordination. Cervical range of motion supports head and neck movement by contributing to head stabilization during activities of daily living and allowing head orientation in various directions. The literature has demonstrated a reduction in cervical range of motion in individuals with chronic neck pain, and this limitation has been reported to be associated with neck pain severity and cervical functional status.

Therefore, elucidating the pathology of such pain and its associated factors in terms of frequency and impact on daily life is of great importance, and several studies have been conducted to date to investigate these aspects. Nevertheless, many factors related to the pathology and associated parameters of this type of pain remain unclear. Recently, the relationship between body composition-including muscle and fat mass-and various health problems has been reported, and increasing evidence has emerged regarding the role of body composition in different health conditions. For example, increased fat mass combined with age-related muscle loss has been associated with a higher risk of disability and mortality. On the other hand, some researchers have reported associations between body composition and musculoskeletal pain, demonstrating that greater fat mass and reduced muscle mass as body composition factors are related to musculoskeletal pain. In light of this information, studies investigating the effects of body composition in individuals with non-specific neck pain appear to be limited, particularly with respect to the inclusion of objective measurements.