Muscular Endurance And Its Association With Neck Pain, Disability, Neck Awareness, And Kinesiophobia

The aim of this study was to investigate the relationship of muscular endurance of the trunk, upper extremities, and scapular region as well as cervical region, with pain, neck awareness, and kinesiophobia in patients with cervical disc herniation. Thirty-six patients between 18-65 years with a diagnosis of cervical disc herniation and having neck pain of 2 and above at rest according to the Visual Analogue Scale (VAS) were included in the study. After the evaluation of musculoskeletal system, endurance tests were performed for 9 muscles/muscle groups in the cervical and scapular regions, upper limb, and trunk. Pain severity was measured by VAS and Neck Disability Index (NDI), neck awareness with Fremantle Neck Awareness Questionnaire (FreNAQ), and fear of movement with Tampa Kinesiophobia Scale (TKS).

Cervical disc herniation occurs as a result of a sudden trauma or chemical/mechanical degenerative changes in the cervical spine, and is more common in women. The most common age range for disc herniation is 51-60 years with the increase in prevalence with age in both genders, and the most affected disc level is C6-C7. The clinical presentation such as weakness in cervical musculature, decreased endurance, loss of motor control and postural stabilization, changes in reflexes, loss of sensation, and movement limitations varies based on the location of the disc. The pain caused by any damage or compression in the cervical spinal nerve root is seen along the affected nerve dermatome as well as the head, neck, scapula, shoulder, and upper extremity, and accompanied by spasm in the cervical muscles.

Cervical muscles have a large number of sensory receptors responsible for vestibular, visual, and postural control by the deep suboccipital muscles with dense muscle spindles. They are responsible for the stabilization of the head, neck, and the thoracic region against involuntary perturbation by maintaining the continuity of the posture; they ensure the mobility of neck and upper limbs, and contribute neck awareness and postural reflexes. Intense proprioceptive receptors of deep cervical muscles support the motor control of the trunk muscles, mutually trunk muscles contribute to stabilization of the head and neck; and through the thoracolumbar fascia they work in coordination with scapular muscles. It has been known that any involvement of cervical, trunk, and scapular region muscles, as a whole, contribute to the etiology of the neck pain in patients due to their strong anatomical relations. In addition, the contribution of the upper extremity muscles in the stabilization of the cervical spine and the triggering of neck pain during upper extremity movements also reveal the importance of the motor control of upper extremity muscles in these patients.

Endurance of the cervical muscles has been known to have more responsibility on the spinal stabilization than strength in patients with chronic neck pain, causing an increase in pain with the decrease in endurance. In cervical disc herniation, the pathology in the cervical region causing the malalignment of the spine not only deteriorate the strength and endurance of the neck muscles, but it also affects other muscles around the spine. Further, proprioceptive receptors in the cervical muscles lose the ability to detect changes in muscle tension due to the reduced endurance, which in turn affect neck awareness. On the other hand, since chronic pain is closely related to cognitive and behavioral factors, pain worsens as a result of activity avoidance according to the fear-avoidance model, hence the kinesiophobia also increases by the decrease in cervical muscle endurance in chronic neck pain.

Recent studies revealed the connection between the endurance of neck muscles and pain, neck awareness, and fear of movement in patients with cervical disc herniation in literature. However, the evidence related to the relation between scapular, upper extremities, and trunk muscles' endurance and neck pain, neck awareness, and fear of movement has still been lacking. Therefore, the aim of the present study was to investigate the association between the endurance of these muscles and neck pain, neck awareness, and kinesiophobia in patients with cervical disc herniation.

Eligibility Criteria:
Inclusion Criteria:

1. Having a diagnosis of cervical disc herniation confirmed by MR radiography, direct radiography, and clinical and physical examination
2. Having neck pain at rest for 3 months or more with a severity of 2 or above according to the Visual Analogue Scale (VAS)
3. Having a score of 5 or more from the NDI
4. Being able to comply with the instructions of the physiotherapist

Exclusion Criteria:

1. Patients with spinal tumors/deformities/congenital malformations
2. Who underwent cervical or upper extremity surgery in the previous 6 months were excluded from the study.