## 3 Results  
One noteworthy outcome of the pilot study involves the identification of the general pattern of the diving header (Figure 5). The diving header exhibits characteristics akin to projectile motion. Following take-off, the head experiences an initial decrease in speed attributable to the upward motion of the body during the flying phase. Subsequently, as the body descends in the flying phase, the head's speed undergoes a reversal, transitioning into an increase. Theoretically, the head's speed should culminate at its maximum upon impact with the ball. However, in all but one of the 26 trials, the head's speed attains its maximum before the impact, leading to a phenomenon known as speed drop, wherein the speed diminishes once again upon ball impact. From a mechanical standpoint, this speed drop in the head has the potential to adversely affect the momentum transfer from the head to the ball. Accompanying the speed drop is the time offset, denoting the temporal disparity between the moment when the head reaches its maximum speed and the instance of impact. These novel findings have prompted the inclusion of two additional parameters, namely head speed drop (%) and time offset (%), in the quantitative analysis. \[\text{Head speed drop }(\%)=(\text{Max V}_{\text{ball}}-\text{V}_{\text{head- impact}})/\text{Max V}_{\text{ball}} \tag{3}\]  
\[\text{Time offset }(\%)=(\text{time at impact }-\text{time at Max V}_{\text{ball}})/\text{t}_{\text{ flying}} \tag{4}\]  
where Vball: ball velocity, t flying: airborne/flying time from take-off to impact. A rating scale established for the maximal standing long jump test in adults [22] designates jumps exceeding 2.5 m as excellent. The outcomes presented in Table 1 affirm the excellence of the subjects in this study, demonstrating a mean jumping distance of 2.63 m, equivalent to approximately 1.54 times their body height. Notably, for physically excellent subjects, the EOR approximates 4.5 m, constituting around 2.64 times their body height. These accomplished subjects have achieved BSE exceeding 9 m/s. The detailed in-depth analysis results are delineated in Table 2, encompassing various parameters linked to the diving header. The flying distance in this investigation spans from 2.81 to 4.73 m, the ball height at impact ranges from 0.61 to 1.41 m, and the flying time from take-off to head impact with the ball varies from 0.31 to 0.65 s. Correlation analyses reveal that these factors do not significantly influence BSE (\(\mid\) r \(\mid\) \(<\) 0.30 and \(p\) \(>\) 0.05). Furthermore, the mean maximum head speed is recorded at 7.34 m/s, indicating a low correlation (0.5 \(>\) \(\mid\) r \(\mid\) \(>\) 0.3) [30] with BSE, suggesting a potential relationship between these variables. Notably, the head speed at impact averages 6.63 m/s, demonstrating a strong correlation (0.7 \(>\) \(\mid\) r \(\mid\) 0.5) [30] with high significance (\(p\) = 0.00). The head speed drop, amounting to 4.93% of maximum head speed on average, exhibited a robust negative correlation (r = -0.77, \(p\) = 0.00) with BSE, indicating that the lower the speed drop, the greater the momentum transfer to the ball during impact. Similarly, the time offset, averaging 26.29% of the flying phase, displayed a strong negative correlation (r = -0.67, \(p\) = 0.00) with BSE, emphasizing the temporal aspects influencing the effectiveness of the diving header technique, i.e., the smaller the time offset, the more effective the header is. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & \(\mu\) **\(\pm\) SD** & **Normalized by BH** \\ \hline Max standing long jump (N = 12) & 2.63 \(\pm\) 0.06 m & 1.54 \(\pm\) 0.01 \\ EOR (N = 10) & 4.42 \(\pm\) 0.26 m & 2.64 \(\pm\) 0.18 \\ BSE (N = 26) & 9.35 \(\pm\) 1.97 m/s & \\ \hline \hline \end{tabular} \(\mu\): average, SD: standard deviation, EOR: effective offensive range, BSE: ball speed enhancement.  
\end{table} 
Table 1: The distinguishing physical features, EOR, and BSE of the subjects tested.