Normal values of abdominal muscles thickness in healthy children using ultrasonography.

Abdominal muscles are one of the important elements to support the lumbar spine. Evaluation of muscle thickness using ultrasonography (US) is considered to be a source of information from muscles characteristics. The purpose of this study was to demonstrate normal reference data of abdominal muscles thickness and subcutaneous fat in adolescents using US. A random sample of 160 healthy adolescents (80 boys and 80 girls) at the age range of 15-18 years was recruited. Three abdominal muscles including Transversus Abdominis (TA), Internal Oblique (IO), External Oblique (EO) and subcutaneous fat (SF) were bilaterally measured using US. The range of normal values for TA muscle thickness was between 2.31 and 2.57 mm, for IO muscle thickness was between 4.02 and 5.15 mm and for EO muscle thickness was between 2.81 and 3.17 mm. The normal patterns of abdominal muscles were found as IO > EO > TA at both sides. Boys were taller, heavier with greater body mass index (BMI) and had larger abdominal muscles thickness than girls. A weak negative correlation was found between age and muscles size [r = (-0.06) - (-0.23), p < .05], but a significant positive correlation was found between BMI and muscle size (r = 0.21-0.68, p < .05). It seems that abdominal muscles thickness in adolescents followed the same pattern of muscle size in adults. BMI appeared to be the best predictor of muscle thickness. However, further studies are recommended to support the findings of the present study.