# Respiratory Muscle Strength as a Predictor of VO2 max and Aerobic Endurance in Competitive Athletes
## 3 Results  
The statistical analyses of the VO2 max, VE, VO2, and VCO2 parameters are presented in tables below. According to Table 2, the parameters indicate a strong and significant relationship with VO2 max/kg (R = 0, 715, R2 = 0.511, \(p<0.05\)). The above-mentioned variables together explain 51% of the total variance in VO2 max/kg (Figure 1). According to the standardized regression coefficient (\(\beta\)), mid-axilla circumference, MEP and inspiratory subcostal circumference values have a significant effect on VO2 max, while the other predictor variables do not seem to have a significant effect on VO2 max. When examining the bilateral and partial correlations between the predictor variables and VO2 max, we found a negative correlation between the MIP, mid-axilla, and axilla circumference measurements during inspiration and expiration, and the mid-subcostal and subcostal circumference measurements during inspiration and expiration. Also, a positive relationship was determined between MEP and MVV values (Figure 1) \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline
**Characteristics** & **X** & **Sd** & **B** & **SE** & \(\beta\) & **T** & \(p\) & **Zero-Order** & **Partial** \\ \hline (Constant) & & & 131.529 & 17.495 & & 7.518 & 0 & & \\ MIP (cm/H2O) & 99.08 & 29.7 & \(-\)0.098 & 0.065 & \(-\)0.271 & \(-\)1.504 & 0.143 & \(-\)0.092 & \(-\)0.265 \\ MEP (cm/H2O) & 130.95 & 42.82 & 0.148 & 0.048 & 0.59 & 3.091 & **0.004** & 0.108 & 0.491 \\ MAC (cm) & 91.4 & 10.72 & \(-\)3.498 & 1.642 & \(-\)3.489 & \(-\)2.13 & **0.041** & \(-\)0.42 & \(-\)0.363 \\ ACI (cm) & 95.2 & 10.216 & 0.511 & 0.932 & 0.486 & 0.548 & 0.588 & \(-\)0.405 & 0.1 \\ ACE (cm) & 89.13 & 10.827 & 1.926 & 1.313 & 1.941 & 1.467 & 0.153 & \(-\)0.405 & 0.259 \\ MSC (cm) & 78.82 & 10.454 & 1.064 & 1.072 & 1.035 & 0.993 & 0.329 & \(-\)0.344 & 0.178 \\ SCI (cm) & 82.95 & 9.462 & \(-\)1.329 & 0.681 & \(-\)1.17 & \(-\)1.953 & **0.045** & \(-\)0.366 & \(-\)0.336 \\ SCE (cm) & 76.63 & 10.505 & 0.42 & 0.939 & 0.41 & 0.447 & 0.658 & \(-\)0.34 & 0.081 \\ MVV & 135.63 & 38.39 & 0.08 & 0.05 & 0.286 & 1.603 & 0.120 & 0.027 & 0.281 \\ \hline \hline \multicolumn{8}{l}{\(\text{F}_{(9-30)}=3.477\)} & \multicolumn{8}{c}{P = 0.005} \\ \multicolumn{8}{l}{\(\text{R}^{2}=0.511\)} & \multicolumn{8}{c}{R2 = 0.511} \\ \hline \end{tabular}
\begin{tabular}{l c c c c c c c} \hline \hline  & & MIP: Maximum inspiratory pressure, MEP: Maximum expiratory pressure, MVV: Maximum voluntary ventilation, MAC: Mid-Axilla circumference, ACI: Axilla circumference On Inspiration, ACE: Axilla circumference On Expiration, MSC: Mid-Subcostal circumference, SCI: Subcostal Circumference On Inspiration, SCE: Subcostal Circumference On Expiration; X: Mean, SD: Standard Deviation, SE: Standard Error, B: Regression Coefficient, \(\beta\): Standardized Regression Coefficient, T: t-Statistic, \(p\): \(p\)-Value, Zero-order: Bivariate Correlation Values, Partial: Correlation Values. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Regression analysis results regarding VO2 max/kg (Mean \(\pm\) S.D. = 58.52 \(\pm\) 10.74 mL/kg/min) prediction of the parameters. According to Table 3, the parameters show a strong and significant relationship with VE (R = 0.760, R\({}^{2}\) = 0.577, \(p\) < 0.05). The mentioned variables together explain 57% of the total variance in VE (Figure 2). According to the standardized regression coefficient (\(\beta\)), the values of MEP and inspiratory subcostal circumference measurement have a significant effect on VE, while the other predictor variables do not seem to have a significant effect on VE. When the bilateral and partial correlations between the predictor variables and VE were examined, low-level correlations were found between MIP and VE, and moderate and positive correlations with other parameters.