# The Influence of Ski Waist-Width and Fatigue on Knee-Joint Stability and Skier's Balance
## 3 Results  
The knee flexion angle was predetermined and monitored in real time for all measurements on the ski simulator, and the results revealed that there were no statistically significant differences in knee flexion parameters. There were also no statistically significant differences in knee rotation parameters, whether with the ski waist-width parameter or with time before or after fatigue (Figure 3). The knee abduction was significantly larger in connection with the wide skis (Figure 4) compared to the narrow ones (\(t=-5.1\); \(p<0.01\); \(d=0.46\)). Figure 4: Knee abduction/adduction in a prefatigued state (before F) and at different times after fatigue (after F) with two different ski waist-widths. + depicts statistically significant difference compared to prefatigued state (\(p<0.05\)); * depicts statistically significant difference between all-narrow against all-wide waist-width measurements. Figure 3: External tibial rotation in a prefatigued state (before F) and at different times after fatigue (after F) with two different ski waist-widths. After fatigue, there was significant increase in knee abduction with narrow skis (\(t=-2.16;p=0.05\); \(d=0.31\)), as well as with the wide ones (\(t=-2.39;p<0.05;d=0.41\)). Significant differences were observed in V\({}_{\rm{AP}}\) with wide skis compared to narrow ones (F = 3.78; \(p<0.05;\eta^{2}=0.27\)) (Figure 5). The V\({}_{\rm{AP}}\) value for wide skis was significantly higher compared to that for narrow ones (\(t=-3.44\); \(p<0.01\); \(d=0.52\)). With narrow skis, all three after fatigue V\({}_{\rm{AP}}\) values were significantly higher compared to the prefatigue value with the immediate after fatigue value being the highest (\(t=-2.70\); \(p<0.05\); \(d=0.42\)). There were significantly higher V\({}_{\rm{ML}}\) values with wide skis (F = 19.94; \(p<0.01\); \(\eta^{2}=0.67\)) compared to narrow ones (\(t=-4.87\); \(p<0.01\); \(d=0.70\)) (Figure 6). Figure 5: Center of pressure (CoP) velocity in anteroposterior direction (V\({}_{\rm{AP}}\)) in a prefatigued state (before F) and at different times after fatigue (after F) with two different ski waist-widths. + depicts statistically significant difference compared to prefatigued state (\(p<0.05\)); * depicts statistically significant difference between all-narrow against all-wide waist-width measurements. Figure 6: CoP velocity in mediolateral direction (V\({}_{\rm{ML}}\)) in a prefatigued state (before F) and at different times after fatigue (after F) with two different ski waist-widths. + depicts statistically significant difference compared to prefatigued state (\(p<0.05\)); * depicts statistically significant difference between all-narrow against all-wide waist-width measurements. The effect of time was statistically significant for narrow skis only (F = 4.42; \(p<0.01\); \(\eta^{2}=0.29\)). Specifically, there was an increment in V\({}_{\rm ML}\) immediately after fatigue compared to the prefatigue state with narrow skis (\(t=-3.73\); \(p<0.01\); \(d=0.56\)). The results demonstrated significant differences in A\({}_{\rm ap}\) values between different ski widths (F = 4.89; \(p<0.05\); \(\eta^{2}=0.31\)) (Figure 7). The A\({}_{\rm AP}\) values were significantly higher with wide skis compared to narrow ones (\(t=2.23\); \(p<0.05\); \(d=0.31\)). The differences between pre and after fatigue times were significant with wide skis only (F = 4.28; \(p<0.05\); \(\eta^{2}=0.28\)). There was a decrement in A\({}_{\rm AP}\) value 2 min after fatigue compared to the state immediately after fatigue (\(t=2.92\); \(p<0.05\); \(d=0.38\)). There were significant differences in A\({}_{\rm ML}\) values between different ski widths (F = 20.36; \(p<0.01\); \(\eta^{2}=0.63\)). The A\({}_{\rm ML}\) values were significantly higher with wide skis compared to narrow ones (\(t=-5.18\); \(p<0.01\); \(d=0.69\)) (Figure 8). Figure 8: CoP amplitude in mediolateral direction (A\({}_{\rm ML}\)) in a prefatigued state (before F) and at different times after fatigue (after F) with two different ski waist-widths.