A RELATIONSHIP BETWEEN HAMSTRING SHORTENING, BODY POSTURE AND BODY MASS INDEX IN BOYS UNDERTAKING FOOTBALL TRAINING

Adequate length and tension of postural muscles are necessary to maintain proper body posture and enable basic movement patterns to be correctly carried out. These muscles include the hamstrings. Research results show that these are often characterised by reduced elasticity and excessive passive stiffness. The aim of our study was to assess the relationship between hamstring shortening, body posture and excessive body weight in physically active boys. The study involved 69 boys aged from 6 to 19 years who regularly took part in football training (at least three times a week) for at least 12 months. Body height (calibrated anthropometer), body weight (electronic balance TANITA), torso positioning in three planes (ultrasonic system ZEBIS Pointer) and the flexibility of the hamstrings (goniometer) were analysed. Descriptive statistics, cardinality tables, the Kruskal-Wallis test and an effect size were used in statistical analysis. The reduction of hamstring elasticity in both legs was diagnosed in 50.72 % and in one leg in 13.05 % of the boys studied, while 24.65 % were overweight and 4.35 % were obese. No significant differences in the torso position were found in the groups distinguished by hamstring flexibility. However, subjects with hamstring shortening tended to have increased pelvic torsion, increased angular kyphosis and lumbar lordosis, have greater asymmetry of the right and left pelvis and shoulders, and increased scoliotic deformities. A significant correlation was found between hamstring flexibility, body weight and body mass index (BMI). Common hamstring shortening in boys taking part in football training does not significantly affect body posture but significantly correlates with body weight and BMI. Stretching exercises and soft tissue mobilisation techniques should be included in the football training of young players.