## 4 Discussion  
Posture is determined not only by passive stabilizing structures (i.e., the skeleton and ligaments) but also by muscular activity [36]. Given that these can presumably change as a result of muscular fatigue due to previous exertion, this pilot study was designed to examine the stability of posture parameters over the course of the day. The pelvic tilt proved to be particularly stable over the course of the day, with high ICC values of 0.95 and 0.97, indicating high reliability [50], and a lack of significance of the time factor in the repeated ANOVA, keeping in mind the minimum detectable changes of almost 4\({}^{\circ}\) (Table 6). The pelvic tilt is particularly relevant for an analysis of posture, as the pelvis--or, rather, the sacrum--is the anatomical base for the spine, and changes in pelvic position can therefore affect the posture of the trunk. An increase in pelvic tilt can also increase lumbar lordosis [30], increase the load on the intervertebral joints [51], and create a hollow back [32; 52]. The fact that the pelvic tilt decreased during the transition from a passive habitual posture to an active posture is consistent with the change in posture parameters in our own earlier studies, as is the fact that posture deteriorated (in this case, the pelvic tilt increased again) when the eyes were closed due to reduced sensory information [42]. [PERSON] et al. examined the reproducibility of some sagittal parameters such as pelvic tilt and pelvic displacement in children [44]. They also found good reproducibility both after one hour and after one week. However, only children (aged 7-10 years) in a relaxed state were examined. In the prevention of sports injuries, however, the state after muscular exertion is more important. Pelvic tilt is also important in the context of injury prevention in sports. Recent studies have suggested that the alignment of the pelvis in the sagittal plane can influence the risk of muscle injuries in sports. As [PERSON] and [PERSON] were able to demonstrate an increase in \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Posture** & **SEM** & **MDC** \\ \hline \multirow{3}{*}{Pelvic tilt} & Hab & 1.41 & 3.91 \\  & Act & 1.01 & 2.81 \\  & Aec & 1.42 & 3.93 \\ \hline \multirow{3}{*}{Body lean} & Hab & 0.51 & 1.42 \\  & Act & 0.56 & 1.55 \\  & Aec & 0.60 & 1.66 \\ \hline \multirow{3}{*}{Trunk lean} & Hab & 0.76 & 2.12 \\  & Act & 0.81 & 2.25 \\ \cline{1-1}  & Aec & 0.67 & 1.86 \\ \hline \multirow{3}{*}{Pelvic displacement} & Hab & 0.87 & 2.42 \\  & Act & 1.06 & 2.94 \\ \cline{1-1}  & Aec & 0.98 & 2.70 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Standard errors of the measurements (SEM) and minimally detectable changes (MDC) for all parameters in all postures; Hab—habitual, Act—active, Aec—active eyes closed. All values in degrees. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Comparison** & **t** & \(p\) & **Cohen’s d** & **95\% Confidence Interval** \\ \hline \multirow{3}{*}{Pelvic displacement} & T1 vs. T2 & \(-\)3.31 & 0.005 * & 0.45 & \([-0.77;\,-0.19]\) \\ \cline{2-6}  & T1 vs. T3 & \(-\)3.71 & 0.001 * & 0.51 & \([-0.79;\,-0.24]\) \\ \cline{2-6}  & T2 vs. T3 & \(-\)0.23 & 1.00 & 0.03 & \([-0.32;\,0.26]\) \\ \hline \hline \end{tabular}
\end{table} 
Table 5: _Cont._hamstring injuries with a pelvic tilt exceeding 13\({}^{\circ}\)[20], a possible increase in pelvic tilt in the habitual position during the course of the day is significant. [PERSON] and [PERSON] were able to show that anterior pelvic tilt in soccer players also changes the kinematics in the hip and knee joints, presumably increasing the risk of injury [10]. Even if the pelvic tilt statistically remains constant over our observed group during the course of the day, one must also consider individual results. Figure 3 and Table 2 show that the standard deviation of the pelvic tilt is significantly higher than that of the other parameters.