# Effects of Age and Sex on the Kinematics of the Sprinting Technique in the Maximum Velocity Phase
## 3 Results

Table 4: Mean \(\pm\) standard deviation of the linear and angular kinematics of the lower extremities* points and segments. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline  & & \multicolumn{2}{c}{**Sex**} & \multicolumn{3}{c}{**Age**} & \multicolumn{3}{c}{**Interaction**} \\
**Parameter** & **F** & **_p_** & **\(\boldsymbol{\eta_{p}}\)2** & **F** & **_p_** & \(\boldsymbol{\eta_{p}}\)2** & **F** & **_p_ & \(\boldsymbol{\eta_{p}}\)2** \\ \hline Step length (SL, m) & 2.404 & 0.130 & 0.061 & 111.041 & \textless{}0.001 * & 0.755 & 1.802 & 0.188 & 0.046 \\ Step length (SL, \%body height) & 1.719 & 0.198 & 0.046 & 45.637 & \textless{}0.001 * & 0.559 & 0.001 & 0.971 & 0.000 \\ Step frequency (SF, Hz) & 7.130 & 0.011 * & 0.165 & 11.740 & 0.002 * & 0.246 & 2.030 & 0.163 & 0.053 \\ Contact time (T\({}_{\text{C}}\), s) & 8.204 & 0.007 * & 0.178 & 51.074 & \textless{}0.001 * & 0.573 & 1.708 & 0.199 & 0.043 \\ Contact time (T\({}_{\text{C}}\), \% step time) & 2.025 & 0.163 & 0.051 & 54.307 & \textless{}0.001 * & 0.588 & 0.366 & 0.549 & 0.010 \\ Flight time (T\({}_{\text{f}}\), s) & 0.070 & 0.792 & 0.002 & 5.583 & 0.024 * & 0.134 & 0.000 & 0.995 & 0.000 \\ Horizontal BCM take-off velocity & & 23.789 & \textless{}0.001 * & 0.391 & 158.841 & \textless{}0.001 * & 0.811 & 18.822 & \textless{}0.001 * & 0.337 \\ Vertical BCM take-off velocity & & & & & & & & \\ (V\({}_{\text{TO}}\), m/s) & 0.006 & 0.939 & 0.000 & 9.408 & 0.004 * & 0.203 & 1.043 & 0.314 & 0.027 \\ Angle of projection (AngPr, deg) & 1.663 & 0.205 & 0.043 & 1.116 & 0.298 & 0.029 & 4.981 & 0.032 * & 0.119 \\ Touchdown distance (\(\mathsf{ST}_{\text{TD}}\), m) & 4.216 & 0.047 * & 0.102 & 1.073 & 0.307 & 0.028 & 1.429 & 0.240 & 0.037 \\ Touchdown distance (\(\mathsf{ST}_{\text{TD}}\), \%body height) & 3.759 & 0.060 & 0.095 & 10.788 & 0.002 * & 0.231 & 3.261 & 0.079 & 0.083 \\ Take-off distance (\(\mathsf{ST}_{\text{TO}}\), m) & 1.401 & 0.244 & 0.036 & 11.991 & 0.001 * & 0.245 & 0.393 & 0.534 & 0.011 \\ Take-off distance (\(\mathsf{ST}_{\text{TO}}\), \%body height) & 0.025 & 0.875 & 0.001 & 0.099 & 0.754 & 0.003 & 1.598 & 0.214 & 0.042 \\ BCM height at touchdown (H\({}_{\text{TD}}\), \%body height) & & 0.802 & 0.376 & 0.022 & 0.004 & 0.950 & 0.000 & 1.841 & 0.183 & 0.049 \\ Minimum BCM height & & & & & & & & & \\ (H\(\Delta\)M, \%body height) & & & & & & & & \\ Lowering of BCM during support phase & & & & & & & & & \\ (\(\Delta\)H\({}_{\text{AM}}\), m) & 0.223 & 0.639 & 0.006 & 9.733 & 0.003 * & 0.208 & 0.223 & 0.639 & 0.006 \\ BCM height at take-off (H\({}_{\text{TO}}\), \%body height) & & &The only exception was the angular velocity of the ankle joint at touchdown, where significant (\(p<0.05\)) sex differences were observed in both adults and prepubescents. A significant (\(p<0.05\)) main effect of age was evident mainly for the ankle joint of both legs, as well as for the angular kinematics of the swing leg's knee joint. A significant (\(p<0.05\)) interaction of age \(\times\) sex was found only for the swing leg's knee angle at take-off. Figures 2 and 3 depict representational stick figures of AF vs. PPG and AM vs. PPB, respectively. The qualitative information derived from Figures 2 and 3 suggest that prepubescents performed the analyzed maximum velocity phase sprint step in a more upright torso position, with less dynamic movement of the arms and the swing leg, increased knee flexion during the braking phase, and less active ankle movement at both touchdown and take-off.