# The Influence of Ski Waist-Width and Fatigue on Knee-Joint Stability and Skier's Balance
## 3 Results
+ 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 7: CoP amplitude in anteroposterior direction (A\({}_{\rm AP}\)) in a prefatigued state (before F) and at different times after fatigue (after F) with two different ski waist-widths. * depicts statistically significant difference between all-narrow against all-wide waist-width measurements. The effect of time of measurement was statistically significant for narrow skis only (F = 5.00; \(p<0.01\); \(\eta^{2}\) = 0.31) and A\({}_{\rm ML}\) was significantly higher only immediately after fatigue (\(t=-3.44\); \(p<0.01\); \(d=0.52\)). Significant differences were observed in MF\({}_{\rm AP}\) with different ski widths (F = 5.93; \(p<0.01\); \(\eta^{2}=0.37\)). The MF\({}_{\rm AP}\) value was significantly lower with wide skis compared to the narrow ones (\(t=2.86\); \(p<0.05\); \(d=0.43\)) (Figure 9). The differences between different times of measurement were significant with wide skis only (F = 3.38; \(p<0.05\); \(\eta^{2}=0.30\)) and MF\({}_{\rm AP}\) was significantly higher 2 min after fatiguing compared to the prefatigue value (\(t=-4.17\); \(p<0.01\); \(d=0.66\)), as well as 4 min after fatigue compared to the prefatigue value (\(t=-3.32\); \(p<0.01\); \(d=0.50\)). With narrow skis, there was a significant increment in MF\({}_{\rm AP}\) value only at 4 min after fatigue compared to the prefatigue value (\(t=-3.5\); \(p<0.01\); \(d=0.53\)). There were significant differences in MF\({}_{\rm ML}\) values with time of measurement (F = 3.96; \(p<0.05\); \(\eta^{2}=0.36\)), as well as with different ski widths (F = 3.70; \(p<0.05\); \(\eta^{2}=0.35\)) (Figure 10). MF\({}_{\rm ML}\) was significantly lower with wide skis compared to narrow ones (\(t=2.33\); \(p<0.05\); \(d=0.31\)). With narrow skis, there was a significant increment in MF\({}_{\rm ML}\) values 4 min after fatigue compared to the prefatigue state (\(t=-3.85\); \(p<0.01\); \(d=0.55\)), as well as 4 min after fatigue compared to immediately after fatigue (\(t=-2.73\); \(p<0.05\); \(d=0.40\)). With wide skis, there was significant difference in MF\({}_{\rm ML}\) value only 4 min after fatigue compared to values 2 min after fatigue (\(t=-2.33\); \(p<0.05\); \(d=0.31\)). With AR values, there were significant differences with different times of measurement (F = 5.36; \(p<0.01\); \(\eta^{2}=0.52\)), as well as with different ski widths (F = 4.33; \(p<0.05\); \(\eta^{2}=0.46\)). There were significantly higher AR values with wide skis compared to narrow ones (\(t=-3.67\); \(p<0.01\); \(d=0.53\)). With respect to different measurement times, there were significant differences in AR value with narrow skis only (F = 5.58; \(p<0.01\); \(\eta^{2}=0.34\)) with all the after fatigue values being significantly higher compared to the prefatigue state. Figure 9: The mean frequency of the power spectrum of CoP in the anteroposterior direction (MF\({}_{\rm AP}\)) in a prefatigued state (before F) and at different times after fatiguing (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.