# Technical-Tactical Analysis of Corner Kicks in Male Soccer: A Systematic Review
## 4 Discussion  
### Qualitative Synthesis  
#### 4.1.1 Execution  
In every soccer match, an average of 9.8 to 10.6 corner kicks are executed [15; 17; 18; 33]. These are approximately evenly distributed between the right and left sides, with some studies showing a slight predominance of corners from the left side [8; 18] and others from the right side [19; 21; 33; 37], but there is no statistically significant difference. Most executions are performed directly [4; 14; 19], but it appears that higher-ranked teams use short (indirect) executions more frequently compared to lower-ranked teams [21]. Additionally,  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline
**Study** & **Q1** & **Q2** & **Q3** & **Q4** & **Q5** & **Q6** & **Q7** & **Q8** & **Q9** & **Q10** & **Q11**  
most corners are executed through aerial routes compared to ground routes. The percentage of aerial executions ranges from 78.2% to 91.6% [4; 14; 19; 33].  
Several authors have investigated the differences between inswinging and outswinging corners, which have trajectories toward or away from the goal, respectively. [PERSON] [17] and [PERSON] et al. [37] found that the majority (54-57%) of corner kicks were executed with an inswinging curve. However, [PERSON] et al. [4], who studied six leagues, found this to be true only in the English Premier League, while in the other five leagues, teams alternated between inswinging and outswinging trajectories. Most authors found that inswinging corners have higher success rates in terms of goals compared to outswinging ones, but the differences were not statistically significant [5; 9; 17; 21]. Considering the delivery zone, [PERSON] et al. [15] found that the most successful kicks were outswing when delivered to the penalty box and inswing when delivered to the near post. Conversely, a statistically significant difference was found in favor of outswinging corners regarding final attempts [5]. Furthermore, it appears that when teams are leading, they prefer outswinging corners, while when they are losing, they opt for inswinging corners [10; 17]. Finally, [PERSON] et al. [18] found that in the 2015/2016 English Premier League Season, the top six teams favored outswinging deliveries, while the bottom six teams favored inswinging deliveries (\(p<0.001\)).  
Most authors who have studied corners have focused on the delivery zone. However, there is significant variability in how researchers divide the defending team's area into zones, making it difficult to draw clear conclusions. Researchers have divided the area into 2 zones (near post/far post) [6; 33; 35], 3 zones [19], 5 zones [5], 6 zones [8; 9; 10], 7 zones [34], 8 zones [14; 37], 9 zones [15; 21], 11 zones [4], 13 zones [18], 16 zones [7], and 66 zones [17]. In studies that divided the area into two zones, it appears that most corners are executed to the near post, but there are conflicting findings regarding the effectiveness of the two zones. In studies with more detailed research dividing the area into more zones, it appears that most corners are executed in the center of the box, 6-9 yards from goal, and this zone had the best success rates for goals [9; 17; 21; 34]. However, [PERSON] et al. [15], considering the curve of the execution, found that the most successful kicks were outswing when delivered to the center of the penalty box and inswing when delivered to the near post, while [PERSON] et al. [5] found that corners directed within the six-yard box and toward its center (goalkeeping zone) more often led to counterattacks by the opposing team. Therefore, not only is it necessary for researchers to agree on how to divide the area into zones, but this parameter should also be examined in conjunction with other variables.