## 4 Discussion  
This study aimed to compare the effectiveness of PIR and SS and to determine which intervention, in addition to TENS, was most effective in reducing neck pain, disability index, and increasing cervical spine movements in working-age patients with chronic non-specific neck pain. All study participants received 12 treatment sessions within a four-week period at the outpatient rehabilitation center. A literature review from 2022 [5] revealed that the burden of neck pain is higher in females than in males, with the highest prevalence occurring between the ages of 45 and 54. However, in the current study, the majority of subjects reporting neck pain were between 30 and 40 years of age, and most patients were women. Our data align with the findings of [PERSON] et al. [43], who found that women, particularly those aged 30 to 39 years, are more likely to complain of neck pain. Non-specific neck pain is prevalent among individuals with sedentary jobs, low levels of physical activity, and occupations requiring constant neck movements. Additionally, even in healthy populations, prolonged static postures can lead to neck pain and discomfort over time [44]. Physical inactivity at work was also noted in this study, as the subjects were engaged in prolonged static positions. In this study hand grip strength (HGS) was expected to be decreased in response to neck pain. As expected, HGS was reduced, and the strength of the non-dominant hand was significantly lower than that of the dominant hand in both groups. A decrease in HGS may be observed as a consequence of manual work. Office workers tend to have weak grips and a great difference between sides [45]. Furthermore, a decrease in hand grip strength (HGS) was observed when measurements were taken with the wrist in flexed or extended positions, as opposed to a neutral position. Additionally, differences in HGS were noted between sitting and standing postures [46; 47]. These variations were attributed to changes in muscle length in flexed and extended positions, resulting in reduced muscle strength. The study by [PERSON] et al. [48] showed that not only wrist positions influence HGS. HGS is significantly lower in flexed, extended, side-bent, or rotated head positions compared to that in neutral positions [48]. Furthermore, non-ergonomic neck postures and the subsequently increased neck muscle tension may provoke cervical nerve root compression, as well as neck pain and headaches [49]. Nerve root irritation in the cervical spine between C5 and C6 may be caused by prolonged and repetitive neck flexion, and this may cause neck pain and potential neurological symptoms along the median nerve [50]. In the current study both interventions significantly reduced neck pain and NDI, but between-group analysis revealed that pain and NDI reduction in the PIR group was significantly higher compared to the SS group. The physiological mechanisms underlying the therapeutic effects of PIR may involve a variety of neurological and biomechanical mechanisms, including hypoalgesia, altered proprioception, motor programming and control, and drainage of tissue fluid congestion [51]. The comparison of cervical ROM within both groups showed significant improvement in all six movements measured and was close to the anatomical ROM of a healthy individual. This might be explained by increases in viscoelastic properties in neck muscles [52]. However pairwise comparison between groups did not show significant differences. In this study, patients were instructed to stretch the muscles of the cervical spine until they felt mild discomfort and to hold that position for 30 s. Stretching for this duration can help minimize negative effects on the neural function of the affected nerve roots. Longer durations of stretching might negatively impact the neurophysiological properties of the involved nerves. These findings can help optimize stretching duration to achieve the desired benefits while avoiding adverse effects on neural function [53].