Supervisors info:
Τσολάκης Χαρίλαος, Καθηγητής, ΣΕΦΑΑ, ΕΚΠΑ
Κουλουβάρης Παναγιώτης, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Παπαγιάννης Γιώργος, Επίκουρος Καθηγητής, Τμήμα Φυσικοθεραπείας, ΠΑΠΕΛ
Summary:
The presence of balance in size, shape, and form with respect to a given axis is defined as symmetry. In the human body, we consider symmetry as that of the vertical axis that divides the body into right and left halves. Thus, any deviation from this symmetry is defined as unilateral asymmetry. The terms asymmetry and bilateral deficit should not be confused as they are two different phenomena that can affect the performance and health of athletes in different ways. The concept of asymmetry is substantive, while bilateral deficit is a mathematical formula serving research purposes. Asymmetries refer to differences between the two sides of the body, such as differences in strength, flexibility, or mobility between the left and right extremities, and may be due to various factors, including injuries, heredity, or inconsistencies in exercise execution. In contrast, unilateral deficit (bilateral deficit/BLD) concerns the reduction in the body's ability to produce force or execute movements when both extremities are used simultaneously compared to the use of each extremity separately.The bilateral deficit is usually determined by the value of the bilateral deficit index (BI) resulting from the following equation: BI [%] = 100 × (bilateral / right unilateral + left unilateral) − 100, where bilateral means the sum of the forces generated by each extremity during bilateral contraction, while unilateral means the sum of the maximum forces generated during bilateral contractions with each extremity separately. In sports, the relationship between asymmetries and unilateral deficit is usually bidirectional, meaning that asymmetries can exacerbate the unilateral deficit and vice versa. Imbalance in strength, for example, between the two sides of the body can lead to performance imbalance during strength or endurance exercises.For this reason, it was deemed appropriate for this particular study to analyze the relationship between asymmetries and bilateral deficit in athletes of different genders and specialties during literature review. The aim of this study is to investigate the effect of a) gender and b) training specialization on unilateral deficits in male and female athletes. The study involved 194 male athletes aged 18.5 ± 4.08 years with a body height of 180.14 ± 10.22 cm and body weight of 73.89 ± 13.8 kg, and 106 female athletes aged 16.91 ± 3.52 years with a body height of 169.78 ± 8.10 cm and body weight of 62.97 ± 8.46 kg. All participants were considered healthy without any known dominance of either lower extremity.This study, based on literature review, appears to be the first to thoroughly investigate the phenomenon of bilateral deficit concerning the depth jump comparing elite young athletes of national teams regarding both genders, the specialization in 16 different sports, and the competitive characteristics (team/individual sports).The measurement process included the depth jump procedure of athletes of different specialties, genders, and ages (maximum jump height in cm from the ground vertically from the special floor, the athlete's contact time with the special floor after the fall from a stable height of 35 cm, and the reactive force index was calculated). Depth jump was chosen because it combines intense eccentric characteristics (body drop), isometric phase during direction change, and concentric force for jump execution.2-3 measurements per athlete were taken, and the best of them was used. Statistical analysis of the collected measurements was performed using the SPSS program, while literature review was conducted to draw safe conclusions and interpret the results.In conclusion, statistically significant differences were observed between the two genders regarding unilateral deficit in the depth jump (BDDJ) and the reactive strength index (BDRSI). Specifically, it appears that the unilateral deficit in BDDJ was greater in male athletes (-10.87 ± 14.00 VS -2.78 ± 16.73) than in females (p=0.001), while the unilateral deficit in BDRSI, which is a derived quantity of flight time/ contact time, seems that both genders had lower performance unilaterally compared to bilateral execution (p=0.001). Regarding the unilateral deficit of the reactive force (p=0.05), it appears that the BDRSI of male athletes in combat sports was higher (23.88 ± 23.82 VS 12.88 ± 20.94) than that of athletes in team sports (p=0.005), which was a similar finding for the female athletes of the study (43.11 ± 50.45 VS 18.62 ± 23.00) (p=0.02). Significant differences were also observed in the contact time between male individual athletes compared to team sports (p=0.032). Specifically, it appears that the unilateral deficit of BDCTDJ was higher in team sports compared to individual sports in male athletes (7.49 ± 0.91 VS 7.57 ± 0.67), while a similar result was observed for female athletes (6.97 ± 0.88 VS 8.72 ± 1.31). It was also observed that the bilateral deficit of BDRSI was higher in individual sports compared to team sports in male athletes (23.96 ± 2.92 VS 20.94 ± 1.85), with a similar result observed in female athletes (46.66 ± 5.92 VS 22.95 ± 3.45). To sum up, unilateral deficit may have different impacts on athletes depending on the type of sport, and it is important for athletes and coaches to address these impacts appropriately in order to improve performance and maintain their health. Therefore, it is important for athletes and coaches to recognize and manage both asymmetries and unilateral deficit in order to improve their performance and reduce the risk of injury.
Keywords:
Athletic performance, Different sports, Lower extremities, Sports, asymmetries, Bilateral deficit
