## 2 Materials and Methods
### Evaluation of Muscle Force
For all other correlations between sleep parameters and muscle parameters, we have weak correlation (Pearson coefficient is less than 0.4) and p value is more than 0.05. These data allow us to affirm, with a probability above 95%, that there are no moderate or good correlations between sleep and muscle parameters. For calculations of the correlation power for this small number of subjects, we use the software _GPover version 3.1.9.6_ ([[https://g-power.apponic.com/](https://g-power.apponic.com/)]([https://g-power.apponic.com/](https://g-power.apponic.com/)) accessed on 12 June 2022), with post hoc power analysis. The parameters used were the Pearson correlation coefficient = 0.478, the sample size = 18 subjects, and the significance level \(\alpha\) = 0.05. Using this software and these data we determine that the power test for Pearson's correlation is 0.69. Multivariate analysis was made using multivariate tests, the MANOVA (multivariate analysis of variance) test, from XL STAT software. \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Variables** & **SQS Score** & **CASQ Score** \\ \hline EGS Medium maximal muscle force (N) & 0.821 & **0.046** \\ EGS Maximal muscle force (N) & 0.932 & 0.519 \\ EGS Duration of maintained maximal muscle force (s) & 0.455 & 0.677 \\ EGD Medium maximal muscle force (N) & 0.372 & 0.507 \\ EGD Maximal muscle force (N) & 0.696 & 0.351 \\ EGD Duration of maintained maximal muscle force & 0.514 & **0.045** \\ FGS Medium maximal muscle force (N) & 0.873 & 0.931 \\ FGS Maximal muscle force (N) & 0.840 & 0.160 \\ FGS Duration of maintained maximal muscle force (s) & **0.045** & 0.566 \\ FGD Medium maximal muscle force (N) & 0.345 & 0.392 \\ FGD Maximal muscle force (N) & 0.625 & 0.306 \\ FGD Duration of maintained maximal muscle force (s) & 0.960 & 0.429 \\ SQS Score & **0** & 0.112 \\ CASQ Score & **0** \\ \hline \hline \end{tabular}
\end{table} 
Table 20: \(p\)-values for Pearson correlation between SQS, CASQ scores and muscle parameters of left and right knee extensors and flexors. \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline
**Variables** & **FGS** & **FGS** & **FGS** & **FGD** & **FGD** & **FGD** \\ \hline EGS Medium maximal muscle force (N) & 0.356 & **0.004** & 0.942 & **0.001** & **<0.0001** & 0.555 \\ EGS Maximal muscle force & 0.330 & **0.028** & 0.300 & **0.000** & **<0.0001** & 0.856 \\ EGS Duration of maintained maximal muscle force (s) & 0.609 & 0.847 & 0.425 & 0.363 & 0.614 & **0.034** \\ EGD Medium maximal muscle force (N) & 0.500 & **0.021** & 0.810 & **0.017** & **0.007** & 0.920 \\ EGD Maximal muscle force & 0.366 & **0.011** & 0.648 & **0.001** & **0.000** & 0.982 \\ EGD Duration of maintained maximal muscle force (s) & 0.580 & 0.111 & 0.907 & 0.483 & 0.286 & 0.190 \\ FGS Medium maximal muscle force (N) & **0** & **0.002** & 0.580 & 0.189 & 0.100 & 0.774 \\ FGS Maximal muscle force & **0** & 0.789 & **0.011** & **0.005** & 0.533 \\ FGS Duration of maintained maximal muscle force (s) & & & **0** & 0.979 & 0.978 & 0.757 \\ FGD Medium maximal muscle force (N) & & & & **0** & **<0.0001** & 0.765 \\ FGD Maximal muscle force & & & & & **0** & 0.536 \\ FGD Duration of maintained maximal muscle force (s) & & & & & **0** \\ \hline \hline \end{tabular}
\end{table} 
Table 19: \(p\)-values for Pearson correlation between muscle parameters of left and right knee extensors and flexors. We made four types of tests:  
* Explanatory variables--we used the results of sleep questionnaires (SQS and CASQ);
* Dependent variables--we used the results on duration of maintained maximal force for all muscle groups studied by us and the medium of maximal force for all muscle groups. The results of questionnaires were divided into three intervals, as shown in Table 21.  
The most frequently used test is the Wilks lambda test.