Relations between fat mass index and hip structure analysis variables in a group of adolescent girls

Abstract

Introduction: The aim of this study was to explore the relationships between fat mass index (FMI) and hip structure analysis (HSA) variables in a group of Lebanese adolescent girls. Method: This study included 52 postmenarcheal adolescent girls aged between 12 and 20 years. Weight and height were measured and body mass index (BMI) was calculated. Body composition and hip bone mineral density (BMD) were assessed by dual-energy X-ray absorptiometry (DXA). FMI and lean mass index (LMI) were calculated as previously described (Kelly et al., 2009). Daily calcium intake and physical activity (h/week) were evaluated using validated questionnaires (Deheeger et al., 1997; Fardellone et al., 1991). To evaluate hip bone strength, DXA scans were analyzed at the femoral neck (FN), the intertrochanteric (IT), and the femoral shaft (FS) by the HSA program (Beck et al., 1990). Cross-sectional area (CSA) and section modulus (Z) were measured from hip BMD profi les (Beck et al., 1990). Results: Daily calcium intake, physical activity (h/week), age and maturation index (the number of years since menarche) were not signifi cantly correlated to HSA variables. FMI was positively correlated to FN CSA (r=0.49; P<0.001), FN Z (r=0.57; P<0.001), IT CSA (r=0.58; P<0.001), IT Z (r=0.58; P<0.001), FS CSA (r=0.56; P<0.001) and FS Z (r=0.56; P<0.001). LMI was positively correlated to FN CSA (r=0.50; P<0.001), FN Z (r=0.63; P<0.001), IT CSA (r=0.66; P<0.001), IT Z (r=0.73; P<0.001), FS CSA (r=0.51; P<0.001) and FS Z (r=0.51; P<0.001). Using multiple linear regression analysis models, LMI was a stronger determinant of FN CSA, FN Z, IT CSA and IT Z than FMI while FMI was a stronger determinant of FS CSA and FS Z than LMI. Conclusion: This study suggests that LMI and FMI are positive determinants of geometric indices of hip bone strength in adolescent girls.