## 3 Results
### Primary Outcome  
In both groups, pain intensity measured by NPRS was severe before the interventions. Repeated measures analysis of variance (ANOVA) revealed a significant effect of time (F [1, 48] = 185.191, \(p\) = 0.000, \(\eta\) = 0.794) and a time \(\times\) group interaction (F [1, 48] = 4.759, \(p\) = 0.034, \(\eta\)2p = 0.090). Subsequent analysis showed that while both interventions significantly reduced pain (\(p\) = 0.000), pain reduction was higher in the PIR group compared to SS (\(p\) = 0.032, [PERSON]'s d = 0.81 large effect size) (Table 2).  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Characteristics**} & **SS Group** & **PIR Group** & **Between-Group Comparison** \\  & **(n = 25)** & **(n = 25)** & **\(p\)-Value** \\ \hline Age, yrs. & 37.72 \(\pm\) 5.23 & 37.12 \(\pm\) 4.41 & 0.663 \\ Height, cm & 176.08 \(\pm\) 9.72 & 175.52 \(\pm\) 10.66 & 0.847 \\ Weight, kg & 69.87 \(\pm\) 10.23 & 68.59 \(\pm\) 10.11 & 0.658 \\ Body mass index, kg/m\({}^{2}\) & 22.42 \(\pm\) 1.68 & 22.15 \(\pm\) 1.73 & 0.580 \\ Women, n (\%) & 15 (60\%) & 18 (72\%) & 0.551 \\ Pain, NPRS score & 6.12 \(\pm\) 1.72 & 6.00 \(\pm\) 1.66 & 0.803 \\ Pain duration, weeks & 18.52 \(\pm\) 5.09 & 18.80 \(\pm\) 4.39 & 0.836 \\ Dominant handgrip strength, kg & 23.96 \(\pm\) 6.60 & 23.64 \(\pm\) 6.77 & 0.866 \\ Non-dominant Handgrip strength, kg & 20.12 \(\pm\) 5.80 & 19.72 \(\pm\) 4.91 & 0.723 \\ Neck disability index, \% & 30.32 \(\pm\) 7.18 & 30.88 \(\pm\) 7.05 & 0.782 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Characteristics of the participants at baseline.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Variable**} & \multicolumn{3}{c}{**SS Group**} & \multicolumn{3}{c}{**PIR Group**} \\  & \multicolumn{3}{c}{**(n = 25)**} & \multicolumn{3}{c}{**(n = 25)**} \\ \cline{2-6}  & **Pre** & **Post** & **Mean** & **Pre** & **Post** & **Mean** \\  & & & **Difference** & **Pre** & **Difference** \\ \hline NPRS score & 6.12 \(\pm\) 1.72 & 3.92 \(\pm\) 1.19 & 2.20 \(\pm\) 1.55 * & 6.00 \(\pm\) 1.66 & 2.96 \(\pm\) 1.81 & 3.04 \(\pm\) 1.14 * \\ Flexion (\({}^{\circ}\)) & 32.84 \(\pm\) 2.87 & 38.88 \(\pm\) 2.57 & 6.04 \(\pm\) 2.09 * & 34.80 \(\pm\) 2.89 & 41.52 \(\pm\) 2.79 & 6.72 \(\pm\) 1.65 * \\ Extension (\({}^{\circ}\)) & 37.08 \(\pm\) 4.65 & 44.52 \(\pm\) 3.89 & 7.44 \(\pm\) 3.75 * & 37.40 \(\pm\) 4.83 & 47.64 \(\pm\) 2.46 & 10.24 \(\pm\) 5.13 * \\ Lateral flexion to & 26.24 \(\pm\) 4.17 & 35.04 \(\pm\) 2.61 & 8.80 \(\pm\) 3.83 * & 27.04 \(\pm\) 3.74 & 37.36 \(\pm\) 2.33 & 10.32 \(\pm\) 3.87 * \\ asymptomatic side (\({}^{\circ}\)) & 36.20 \(\pm\) 1.80 & 38.04 \(\pm\) 2.64 & 1.84 \(\pm\) 3.85 * & 36.44 \(\pm\) 1.36 & 38.92 \(\pm\) 1.41 & 2.48 \(\pm\) 1.53 * \\ Rotation to symptomatic & 56.44 \(\pm\) 3.73 & 62.96 \(\pm\) 3.01 & 6.52 \(\pm\) 4.11 * & 57.28 \(\pm\) 3.63 & 65.52 \(\pm\) 2.60 & 8.24 \(\pm\) 2.89 * \\ Rotation to & & & & & \\ asymptomatic side (\({}^{\circ}\)) & 64.36 \(\pm\) 2.60 & 65.84 \(\pm\) 2.76 & 1.48 \(\pm\) 1.81 * & 63.04 \(\pm\) 3.41 & 64.76 \(\pm\) 2.67 & 1.72 \(\pm\) 2.32 * \\ Handgrip strength, & & & & & \\ dominant hand (kg) & 23.96 \(\pm\) 6.60 & 24.80 \(\pm\) 6.67 & 0.84 \(\pm\) 1.25 * & 23.64 \(\pm\) 6.77 & 24.48 \(\pm\) 6.95 & 0.84 \(\pm\) 1.18 * \\ Handgrip strength, & & & & & \\ non-dominant hand (kg) & 20.12 \(\pm\) 5.80 & 20.76 \(\pm\) 5.46 & 0.64 \(\pm\) 1.22 * & 19.72 \(\pm\) 4.91 & 20.48 \(\pm\) 5.15 & 0.76 \(\pm\) 1.74 * \\ Total NDI score & 30.32 \(\pm\) 7.18 & 23.84 \(\pm\) 5.83 * & 6.48 \(\pm\) 3.53 * & 30.88 \(\pm\) 7.05 & 19.36 \(\pm\) 4.65 & 11.52 \(\pm\) 3.33 * \\ \hline \hline \end{tabular}
\end{table}
Table 2: Pain intensity, cervical spine range of motion, hand grip strength, and neck disability index values in the groups pre- and post-interventions (mean \(\pm\) SD).