# Assessing External Peak Physical Demands in Under-19 Years and Professional Male Football
## 3 Results  
Descriptive statistics for the comparisons are presented in Table 1. For total distance, the model indicated that neither category (\(F_{(1,\,28.70)}\) = 2.45; \(p\) = 0.128), position (\(F_{(4,\,28.56)}\) = 0.68, \(p\) = 0.609), nor their interaction (\(F_{(4,\,28.56)}\) = 1.11, \(p\) = 0.368) yielded significant effects. However, the random effect of player accounted for substantial variance (\(\sigma^{2}\) = 161.18). Model fit indices were log likelihood = \(-\)2157.57, AIC = 4339.15, and BIC = 4387.63. Similarly, for accelerations, no significant main effects were found for category (\(F_{(1,\,29.11)}\) = 1.08; \(p\) = 0.307), position (\(F_{(4,\,28.92)}\) = 1.21, \(p\) = 0.326), or their interaction (\(F_{(4,\,28.92)}\) = 0.31, \(p\) = 0.864). The random effect of player continued to exhibit substantial variance (\(\sigma^{2}\) = 18.21). Model fit indices were log likelihood = \(-\)2428.89, AIC = 2452.89, and BIC = 2501.37.  
By contrast, for HSR distance, significant main effects were found for both category (\(F_{(1,\,29.74)}\) = 5.83; \(p\) = 0.021) and position (\(F_{(4,\,29.55)}\) = 4.00, \(p\) = 0.010), while their interaction was not significant (\(F_{(4,\,29.55)}\) = 0.59, \(p\) = 0.672); the random effect of player was also notable (\(\sigma^{2}\) = 296.66; log likelihood = \(-\)1789.39, AIC = 3602.78, BIC = 3651.26). Specifically, central defender (\(\beta\) = \(-\)6.621, \(p\) = 0.049) and central midfielder (\(\beta\) = \(-\)7.051, \(p\) = 0.009) were associated with significantly lower values, whereas professional players were linked to higher values (\(\beta\) = 3.724, \(p\) = 0.021), which are displayed in Figure 2C. No significant interaction between position and category was observed (all \(p\) > 0.05), indicating that the influence of position remained consistent across categories, and conversely, the effect of category was stable across positions. In the case of HSR effort count, no significant main effects were identified for category (\(F_{(1,\,27.91)}\) = 0.58; \(p\) = 0.450), position (\(F_{(4,\,27.73)}\) = 2.58, \(p\) = 0.059), or their interaction (\(F_{(4,\,27.73)}\) = 0.78, \(p\) = 0.544), although player variance remained substantial (\(\sigma^{2}\) = 18.02; log likelihood = \(-\)1214.84, AIC = 2453.68, BIC = 2502.17).  
Figure 2: Distribution of dependent variables across position and category. (**A**) = Total distance (m); (**B**) = Accelerations (count); (**C**) = High-speed running distance (m); (**D**) = High-speed running efforts (count); (**E**) = Relative sprint distance (m); (**F**) = Relative sprint efforts (count).  
Finally, analyses of RS distance and RS effort revealed no significant main effects of category (\(F_{(1,\,30.33)}=0.01\); \(p=0.899\) and \(F_{(1,\,28.71)}=0.23\); \(p=0.634\), respectively), position (\(F_{(4,\,30.17)}=1.57\), \(p=0.206\) and \(F_{(4,\,28.56)}=1.05\), \(p=0.399\), respectively), or their interactions (\(F_{(4,\,30.17)}=0.54\), \(p=0.702\) and \(F_{(4,\,28.56)}=0.46\), \(p=0.758\), respectively). Nonetheless, the random effect of player continued to account for notable variance in both models (RS distance: \(\sigma^{2}=161.54\); log likelihood \(=-1672.62\), AIC = 3369.25, BIC = 3417.73; RS effort: \(\sigma^{2}=7.97\); log likelihood \(=-1056.01\), AIC = 2136.01, BIC = 2184.50), highlighting individual differences across participants.