Evaluation of young swimmers' start performance in backstroke and freestyle swimming styles based on selected parameters

Aim: When examining research on swimming, it is notable that studies focusing on the mechanics of starts are relatively scarce. The purpose of this study is to investigate the relationship between kinematic parameters of swimmers' freestyle and backstroke start performances with selected performance parameters and postural values. Materials and Methods: A total of 30 competitive swimmers (13 females, 17 males) with an average training age of 3±0.69 years participated in the study. The experiment consisted of three sessions. In the first session, two familiarization sessions were conducted to teach the swimmers the start mechanics to be applied during the experiment. In the second session, biomechanical parameters related to start performance were measured. During this session, participants performed three (3) repetitions of both track and backstroke starts using a starting platform. The start performances were recorded using "GoPro 10, Basic Tripod, and DACTRONICS HS-200 Start System" equipment. The footage was analyzed using the biomechanical analysis software "Kinovea 0.9.5." In the third session, postural analyses of the athletes were conducted using the mobile postural analysis program "Apecs-AI Posture Evaluation and Correction System®️" (Apecs Posture Analysis Pro Plus 8.2.6 Version). Additionally, the "New York Posture Assessment" method was employed for postural evaluation. Among the selected performance parameters, dynamic balance performance was measured using the "TecnoBody PK200" device, and vertical jump performance was assessed using the "Microgate Witty Wireless Training Timer" device. Statistical analyses were performed using SPSS 25.0 software, and the significance level was set at p<0.05. Results:The results of the study revealed a significant positive correlation (p=0.434) between kinematic parameters of track start performance and vertical jump performance in relation to hip angle (HA). Additionally, a significant positive correlation (p=0.382) was found between vertical jump performance and start velocity (SV) performance. Among the postural parameters, a positive correlation was observed between the anterior hip curve and hip height (p=0.569), flight time (p=0.511), water entry distance (p=0.373), and start time (p=0.528). A significant negative correlation (p=-0.371) was found between hip height (HH) and dynamic balance perimeter length (PL) performance. No correlation was identified between track and backstroke start performances and NYPA scores. Conclusions: The study concluded that the two start models require different biomotor characteristics. For track starts, athletes with a higher anterior hip curve value during the starting position exhibited longer flight times and distances, as well as improved start times. This suggests that anterior hip curve value may be a critical indicator of performance. Additionally, vertical power production, as demonstrated by vertical jump performance, supports horizontal power generation required in track starts. In backstroke starts, dynamic balance was found to be a prerequisite for maintaining hip position above the water during the start. Thus, incorporating dynamic balance training into backstroke start teaching and development programs can positively influence start performance. Furthermore, the equipment and systems used in the study, such as "GoPro 10, Basic Tripod," and "Kinovea 0.9.5," were found to be accessible, time-efficient, and effective in providing immediate feedback to athletes, making them suitable for monitoring start performances. Lastly, swimming technique and discipline-specific intensive training programs, due to their repetitive unilateral movement patterns, may have the potential to cause postural dysfunctions and adaptations. The "Apecs-AI Posture Evaluation and Correction System®️" (Apecs Posture Analysis Pro Plus 8.2.6 Version) used in the study was deemed valuable for its cost-effectiveness and accessibility for postural evaluation. Keywords: Swimming, adolescents, posture, biomechanics, kinematics, start.