## 3 Results
### Physical Activity  
The values of physical activity performed per week by the study group appear in Table 7. Most of the volunteers (75%) undertook a moderate level of physical activity, with only a few individuals scoring high (17%) or low (8%) levels. The median time spent sitting was six hours a day.  
\begin{table}
\begin{tabular}{c c c c} \hline  & **Characteristics** & **Short-Term \({}^{\ddagger}\)** & **Long-Term \({}^{\ddagger}\)** \\ \hline Number of participants evaluated & \(n\) & 24 & 25 \\ \hline \multirow{4}{*}{Prone position} & ICC (95\% CI) & 0.992 (0.982-0.997) & 0.937 (0.717–0.979) \\  & \(p\)-value (ICC) & \textless{}0.001 & \textless{}0.001 \\  & Mean \(\pm\) SD \({}^{\ddagger\ddagger}\) & 0.0 \(\pm\) 0.7 & \(-1.1\pm 1.3\) \\  & \(p\)-value (t-test) \({}^{\ddagger\ddagger}\) & 0.855 & \textless{}0.001 \\ \hline \multirow{4}{*}{Sitting position} & ICC (95\% CI) & 0.990 (0.977–0.996) & 0.990 (0.978–0.996) \\  & \(p\)-value (ICC) & \textless{}0.001 & \textless{}0.001 \\ \cline{1-1}  & Mean \(\pm\) SD \({}^{\ddagger\ddagger}\) & 0.5 \(\pm\) 3.0 & \(-0.7\pm 2.9\) \\ \cline{1-1}  & \(p\)-value (t-test) \({}^{\ddagger\ddagger}\) & 0.388 & 0.232 \\ \hline \multirow{4}{*}{Standing position} & ICC (95\% CI) & 0.991 (0.981–0.996) & 0.984 (0.962–0.993) \\  & \(p\)-value (ICC) & \textless{}0.001 & \textless{}0.001 \\ \cline{1-1}  & Mean \(\pm\) SD \({}^{\ddagger\ddagger}\) & \(-0.4\pm\) 2.3 & \(-1.0\pm 2.4\) \\ \cline{1-1}  & \(p\)-value (t-test) \({}^{\ddagger\ddagger}\) & 0.369 & 0.047 \\ \hline \end{tabular} \(n\): number of individuals; ICC: intraclass correlation coefficient; CI: confidence interval; SD: standard deviation. \({}^{\dagger}\) short-term repeatability of measurements assessed at the first visit and after an hour. \({}^{\ddagger\ddagger}\) long-term repeatability of measurements assessed at the first visit and after two weeks. \({}^{\ddagger\ddagger}\) difference between values of isometric lower back extensor strength measured at the first and the second visit, expressed in kilograms.  
\end{table}
Table 4: Maximal isometric lower back extensor strength: short-term and long-term test-retest reliability.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Variable** & **Sex** & **Total** & **18–29 Years** & **30–49 Years** & \(\geq\)**50 Years** & \(p\)**-Value Age** & \(p\)**-Value Sex** \\ \hline MIP (cmH\({}_{2}\)O) \({}^{\ddagger}\) & Male & 112.4 \(\pm\) 19.7 & 115.8 \(\pm\) 10.9 & 112.7 \(\pm\) 19.2 & 104.9 \(\pm\) 34.0 & \multirow{4}{*}{\textless{}0.001} \\  & Female & 82.1 \(\pm\) 22.2 & 75.0 \(\pm\) 23.4 & 84.9 \(\pm\) 20.2 & 87.8 \(\pm\) 26.7 & \multirow{4}{*}{0.573} & \multirow{4}{*}{0.393} \\ \cline{1-1}  & Male & 91.0 \(\pm\) 15.1 & 93.4 \(\pm\) 8.8 & 90.9 \(\pm\) 15.5 & 86.8 \(\pm\) 24.7 & \multirow{4}{*}{0.573} & \multirow{4}{*}{0.393} \\ \cline{1-1}  & Female & 95.8 \(\pm\) 25.8 & 86.2 \(\pm\) 26.9 & 97.6 \(\pm\) 23.2 & 109.5 \(\pm\) 28.4 & \multirow{4}{*}{0.573} & \multirow{4}{*}{0.393} \\ \cline{1-1}  & Male & 164.3 \(\pm\) 30.3 & 157.0 \(\pm\) 31.7 & 166.9 \(\pm\) 27.8 & 170.9 \(\pm\) 38.1 & \multirow{4}{*}{0.439} & \multirow{4}{*}{\textless{}0.001} \\ \cline{1-1}  & Female & 122.8 \(\pm\) 30.6 & 115.7 \(\pm\) 19.5 & 126.6 \(\pm\) 28.3 & 125.7 \(\pm\) 54.4 & \multirow{4}{*}{0.439} & \multirow{4}{*}{\textless{}0.001} \\ \cline{1-1}  & Male & 70.9 \(\pm\) 12.5 & 67.4 \(\pm\) 13.6 & 71.6 \(\pm\) 11.9 & 76.0 \(\pm\) 12.5 & \multirow{4}{*}{0.314} & \multirow{4}{*}{0.020} \\ \cline{1-1}  & Female & 81.3 \(\pm\) 20.3 & 76.1 \(\pm\) 12.8 & 83.3 \(\pm\) 18.6 & 86.0 \(\pm\) 36.1 & \multirow{4}{*}{0.314} & \multirow{4}{*}{0.020} \\ \hline \end{tabular} Data are expressed as mean \(\pm\) standard deviation. MIP: maximum inspiratory pressure; MEP: maximum expiratory pressure. \({}^{\ddaggeragger}\) respiratory muscle strength calculated from the mean value of the 2 nd to 4 th attempts.  
\end{table}
Table 5: Respiratory muscle strength: results.