INTRODUCTION

1. BODY STRUCTURE, PHYSICAL ACTIVITY AND QUANTITATIVE ULTRASOUND MEASUREMENTS IN PREPUBERTAL BOYS M. Szmodis, E. Bosnyák, G. Szőts, E. Trájer, M. Tóth, A. Farkas Faculty of Physical Education and Sport Sciences Semmelweis University, Budapest, Hungary INTRODUCTION Osteopenia and osteoporosis arecommondiseasesintheworld. It is wellknown, thatbonedegenerationcan be preventedordecreasedbyregularphysicalactivity. High-impactexercise, likefootball has beenshownto be associatedwithhigherbonemass. Footballinvolvesrunning, kicking, jumping, tackling, turning, sprinting. Duringthesemovementsthelowerextremitiesareloadedwithhigh-impactforces (Tarakçi and Oral 2009). A quantitativeultrasoundmeasurements is relativelyinexpensive, portable, non-invasive and radiation-freemethod of evaluatingbone status. The main aim of this pilot studywastoanalyzetherelationshipsbetweendifferentphysicalactivitylevels, anthropometric and boneparametersinprepubertalboys. MATERIAL AND METHODS Table 1: Basic statistics of the anthropometric variables The subjectswerenon-athletic (n=34) and soccerplayerprepubertalboys (n=76), groupedalsoasyounger (9-10yrs, n=64) and older (11-12yrs, n=46) ones. They had a 1.5 to 4 years sport relatedexperience. Anthropometric measurements were taken by the suggestion of the IBP (Weiner and Lourie 1969), including estimated body fat percentage (Pařižková 1961) and physique was characterised by Conrad's growth type (1963). Biological age was assessed by anthropometric measurements using the method of Mészáros and Mohácsi (1983). Calcanealquantitativeultrasoundparameterswereregisteredby a Sonost 3000 bonedensitometer. The analysisincludedspeed of sound (SOS, m/s), broadbandultrasoundattenuation (BUA, dB/MHz) and thecalculatedbonequantity index (BQI=αSOS+βBUA, αβ: temperaturecorrections). Correlation patterns of anthropometric variables and bone characteristics for total sample and for subgroups were analyzed. Differences between athletic and non-athletic boys were tested by Student t-test; and ifthe F-test of ANOVA wassignificantfortherespectivemeans (age and physicalactivity), Tukey's post-hoc test wasusedatthe 5% level of effective random error. Table 2: Correlation pattern of anthropometric and bone parameters (in blue italics: significant correlation coefficient) RESULTS AND DISCUSSION Table 1. summarizes the basicstats ofthe anthropometric variables. Thereweremoderatesignificantrelationshipsbetweenage, stature, plastic index and SOS, BUA, BQI forthetotalsample. Innon-athleteseveryboneparametercorrelatedwithagesignificantly and no significantcorrelationwasfoundinathletesbutfor SOS (Table 2, Figure 1). r = 0.22 r = 0.37 r = 0.29 Figure 2:Broadband ultrasound attenuation (BUA, dB/MHz), means and SD Stature (cm) Age (yrs) Plastic index (cm) Figure 1: Significant correlations between age, stature, plastic index and BQI in total sample In comparison of the activity-related subgroups the bone parameters i.e. BUA in dB/MHz (71.92±11.29 vs. 74.38±11.12), SOS in m/s (1493.4 ±10.78 vs. 1497.6±9.57) and BQI (60.16±11.17 vs. 63.00±10.87) did not differ. Bone variables differed significantly by age: SOS (1491.59±9.69 vs. 1499.09±10.24), BUA (70.11±10.69 vs. 76.26±11.13) and BQI (57.27±10.05 vs.66.27±10.45) (Figures 2-4). Figure 3:Speed of sound (SOS, m/s), means and SD SUMMARY The bone variables did not significantly differ in athletes and in non-athletic prepubertal boys, similar to Cvijetić et al. (2003), in contrast to Falk et al. (2003) and Mentzel et al. (2005). It seems that quantity bone parameters depend on the chronological as well as biological age. Although the bone parameters were related with antropometric variables no difference was found at the same age even with various body size. That means that age had the strongest effect on bone parameters in prepubertal boys. The older boys had larger values, so that favourable characteristics of bone in this sample, irrespective to body size. Figure 4:The calculated bone quantity index, means and SD REFERENCES Conrad, K. (1963) Der Konstitutionstypus (2. Aufl.) Springer, Berlin. Cvijetić, S., Barić, I.C., Bolanca, S., Juresa, V., Ozegović, D.D. (2003) Ultrasound bone measurement in children and adolescents. Correlation with nutrition, puberty, anthropometry, and physical activity. Journal of Clinical Epidemiology, 56(6):591-7. Falk, B., Bronsthein, Z., Constantini, N.W., Eliakim, A. 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