# Visual Fixations in Basketball Shooting: Differences between Shooting Conditions
## 2 Materials and Methods  
The sample was formed by 18 athletes (10 females and 8 males), all players from senior teams, playing in national championships (22 \(\pm\) 3.72 years; 172.15 \(\pm\) 9.79 cm; 69.6 \(\pm\) 13.12 kg). Each participant had a minimum of 4 years of experience in organized basketball play, averaging 12.5 \(\pm\) 4.52 years, with no injuries reported in the three months leading up to the study. Prior to taking part in the research, all athletes were thoroughly briefed about the study's purpose and provided their written informed consent. The study was approved by the ethical committee of the Polytechnic of Coimbra and performed according to the Declaration of Helsinki (CEiPC 83/2021). The data from all participants have been recorded and maintained in an anonymous manner. All athletes performed 10 shots from different distances (free throw--4.60 m; 3 points line--6.75 m), angles (45\({}^{\circ}\), 90\({}^{\circ}\), and 135\({}^{\circ}\)) (Figure 1), and with different constraints (gym audience noise (N) and opposition (O)), totaling 1980 valid data points. These positions were chosen because, during basketball games, they are the ones where athletes made the most shots, based on Euroleague statistics data. Statistical analysis from the 2019 Basketball World Cup revealed that there was a positive correlation between the number of three-point shots made in the final and the likelihood of winning the game [40]. Environmental (gym audience noise) and task (opposition) constraints were used to assess their influence on the visual behavior during shooting. The opposition was made by adjustable equipment with different heights, depending on the athlete's height (1.20 * shooter's height), but always at a 1 m distance [41], Figure 2. The simulated gym audience noise of 105 dBA [42] starts before the athlete receives the ball in the first shot of this condition and was made by external speakers, constant during all 10 shots, and simulated hostile spectators. The same audio was used for all players and shots in this condition. The shooting conditions were: B--baseline in 4 positions; N--gym audience noise in 4 positions; O--opposition in 3 positions. The protocol started with a 10 min warm-up, including shooting drills and functional exercises. After that, the athlete was instrumented, and the glasses were placed and adjusted according to the athlete's comfort, as well as the signal detection box (Figure 3). The system was calibrated by fixing one point at 50 cm of distance for, at least, 3 s. The sequence of procedures carried out is shown in Figure 4.  
Figure 5 shows the shot sequence, starting at one of the shooting positions (1 to 4, Figure 1), randomized for each athlete. Ten shots were made in each condition (X1, X2, and X3 with respect to B, O, or N), also in a random sequence, always in the same position, which was only changed after the 2 min rest period. This sequence of shots was made in the 4 shooting positions shown in Figure 1, with the position order being random for each athlete. Figure 1: Tested shooting positions. 1—free throw (4.60 m); 2-3 points line (6.75 m) 45\({}^{\circ}\) angle; 3-3 points line (6.75 m) 90\({}^{\circ}\) angle; 4-3 points line (6.75 m) 135\({}^{\circ}\) angle. Figure 3: Example of an athlete instrumented with the Tobii glasses before data acquisition. Figure 2: Opposition equipment. The sequence of shooting was randomized to reduce the influence of factors such as exercise learning on the task and fatigue. Between conditions in the same position, the athletes had 30 s to rest, and, between positions, they had a 2 min rest. Each athlete received the ball through a chest pass, consistently executed by the same individual, specialized in basketball coaching, and performed a three-point shot immediately, which means catch and shoot. In the free throw, the athlete had a maximum of 5 seconds, the regulated time in basketball games, to carry out his or her routine and shoot.