The aim of this study was to evaluate changes in local and segmental hypersensitivity and endogenous pain inhibition in people with chronic nonspecific neck pain.

Quantitative sensory testing is widely used in human research to investigate the state of the peripheral and central nervous system contributions in pain processing. It is a valuable tool to help identify central sensitization and may be important in the treatment of chronic neck pain. This study is a cross-sectional study. Two groups including chronic neck pain group and healthy volunteers group will be arranged in this study. The healthy subjects will be matched for sex and age in relation to the neck pain group. The pressure pain threshold (PPT) will be measured at the neck muscle in both groups. The cold pressor test will be used in both groups to activate conditioned pain modulation.

1. Chronic neck pain subjects

   Inclusion criteria:

   • Age 21-80 years old.
   • People must have experienced neck pain for at least 3 months and have reported a minimal pain level of 30 (pain threshold) on the 0-100 pain numerical rating scale (NRS) in the last 7 days.

   Exclusion Criteria:

   • Age under 21 or over 80.
   • Patients were excluded if they had taken pain medications on the day of the assessment or if they had serious spinal pathologies, such as fractures, tumors or inflammatory diseases, such as ankylosing spondylitis, nerve root compromise confirmed by clinical neurological tests or severe cardiorespiratory diseases.
   • Those who were pregnant, patients with cancer and those with a cardiac pacemaker were also excluded.

2. Healthy volunteers

Inclusion criteria:

• Age 21-80 years old.
• These participants must not have presented episodes of low back pain for more than 7 days in the last 12 months.

Exclusion Criteria:

• Age below 21 or over 80 years old.
• These participants have presented episodes of low back pain for more than 7 days in the last 12 months.

1. Chronic neck pain subjects People must have experienced neck pain for at least 3 months and have reported a minimal pain level of 30 (pain threshold) on the 0-100 pain numerical rating scale (NRS) in the last 7 days.Patients were excluded if they had taken pain medications on the day of the assessment or if they had serious spinal pathologies. Those who were pregnant, patients with cancer and those with a cardiac pacemaker were also excluded.
2. Healthy volunteers These participants must not have presented episodes of low back pain for more than 7 days in the last 12 months.