## 3 Results
### Synthesis of the Results  
#### 3.3.1 Stretching versus Control  
Seven studies were included in the qualitative synthesis and six in the quantitative synthesis. All the included studies showed statistically significant improvements in internal rotation (MD: 9.80; 95%CI: 6.54, 13.06; I\({}^{2}\): 89%; six studies; 258 athletes) (Figure 2A) and horizontal adduction ROM (MD: 6.55; 95%CI: 2.79, 10.31; I\({}^{2}\): 92%; four studies; 180 athletes) (Figure 2B) after stretching. Qualitative and quantitative synthesis showed no benefits in external rotation ROM after stretching (MD: 1.82; 95%CI: -2.77, 6.42; I\({}^{2}\): 75%; four studies; 82 athletes) (Figure 2C) or in pain intensity after stretching (MD: \(-\)0.51; 95%CI: -1.14, 0.13; I\({}^{2}\): 0%; two studies; 61 athletes) (Figure 2D). The certainty of evidence was downgraded to very low for all the outcome variables.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Author**} & \multicolumn{10}{c}{**Items**} & \multirow{2}{*}{**Total**} \\ \cline{2-13}  & **1** & & **2** & & **3** & **4** & **5** & **6** & **7** & **8** & **9** & **10** & **11** \\ \hline Stretching vs. control & & & & & & & & & & & & & \\ [PERSON] et al., 2021 [38] & Y & Y & N & Y & N & N & Y & Y & Y & Y & 6/10 \\ [PERSON] et al., 2018 [39] & Y & Y & N & Y & N & N & Y & Y & N & Y & Y & 6/10 \\ [PERSON] et al., 2017 [40] & N & Y & Y & Y & N & N & N & Y & Y & Y & Y & 7/10 \\ [PERSON] et al., 2014 [43] & Y & Y & N & N & N & N & Y & N & N & Y & N & 3/10 \\ [PERSON] et al., 2012 [42] & N & Y & N & Y & N & N & N & N & N & Y & Y & 4/10 \\ [PERSON] et al., 2011 [41] & Y & Y & N & Y & N & N & Y & Y & N & Y & Y & 6/10 \\ \hline Stretching plus manual therapy vs. stretching in isolation & & & & & & & & & & & & \\ [PERSON] et al., 2010 [18] & N & Y & N & Y & N & N & Y & Y & N & Y & 6/10 \\ [PERSON] et al., 2017 [21] & Y & N & N & Y & N & N & N & Y & Y & N & Y & 4/10 \\ [PERSON] et al., 2017 [22] & N & Y & N & Y & N & N & N & Y & N & Y & Y & 5/10 \\ [PERSON] et al., 2020 [17] & Y & Y & Y & Y & N & N & N & Y & Y & Y & Y & 7/10 \\ [PERSON] et al., 2021 [16] & Y & Y & Y & N & N & Y & Y & Y & Y & Y & Y & 8/10 \\ \hline Stretching vs. stretching & & & & & & & & & & & & & \\ [PERSON] et al., 2007 [44] & Y & Y & N & Y & N & N & Y & Y & N & Y & Y & 6/10 \\ [PERSON] et al., 2011 [45] & Y & Y & N & Y & N & N & N & N & N & Y & Y & 4/10 \\ [PERSON] et al., 2014 [46] & Y & Y & N & Y & N & N & Y & N & N & Y & Y & 5/10 \\ [PERSON] et al., 2015 [47] & Y & Y & Y & Y & N & N & Y & Y & Y & Y & Y & 8/10 \\ [PERSON] et al., 2021 [48] & Y & Y & Y & Y & N & N & Y & Y & Y & Y & Y & 8/10 \\ \hline \hline \end{tabular}  
* One, eligibility criteria 2, random allocation; 3, concealed allocation; 4, similarity at baseline; 5, blinding of participants; 6, blinding of therapists; 7, blinding of assessors; 8, measures of at least one key outcome from at least 85% of participants initially allocated to groups; 9, intention-to-treat analysis; 10, between-group comparison; 11, point measures and measures of variability. 1 – Yes (1 point), 0 = No (0 point), maximum score = 10 (criterion 1 is not included in scores).  
\end{table}
Table 2: PEDro scale scores.