Relationships of anthropometrical parameters and body composition with bone mineral content or density in young women with different levels of physical activity.

Abstract

The aim of the study was to test the possible relationships of anthropometrical parameters, somatotype and body composition parameters with bone mineral content (BMC) and bone mineral density (BMD, total body, the dominant arm distal radius, antero-posterior lumbar spine--L2-L4, femoral neck) in strength- (n=33) and endurance- (n=32) trained and sedentary normal-weight (n=41) and overweight (n=23) young females. Their body height and mass were measured and BMI calculated. Nine skinfolds, thirteen girths, eight lengths and eight breadths/lengths were measured. Somatotype components were calculated according to Carter and Heath (1990). Whole body fat percentage, fat mass, lean body mass (LBM), BMC and BMD were measured by DXA. The relationship of different BMC and BMD values at each of the regions studied to the different anthropometrical and body composition parameters were analysed by using a stepwise multiple regression analysis. In all groups, BMC is highly dependent on the body mass (31.5-81.2%, R2x100). In the endurance-trained females, BMD is dependent on LBM, especially in both weight-bearing sites (66.2% in L2-L4 and 35.3% in the femoral neck). LBM explained 77.0% of the total variance of BMC in this group. BMC in the strength-trained group is dependent on the lower body anthropometrical parameters--thigh skinfold (18.2%), calf girth (25.2%), trochanterion length (24.1%) and sitting height (51.4%). From the endurance-trained group, BMC is dependent on hip girth (75.2%) or in combination with ankle girth (81.2%). From the length parameters, trochanterion is the most important (55.8%) and from breadths/lengths, sitting height (57.1%). In the normal-weight females, BMC is dependent on the calf girth (31.1%), trochanterion length (28.2%) and sitting height (29.8%). In the overweight group, only chest girth (20.1%) and biacromial breadth/length (27.0%) had a relationship with BMC. From somatotype components, only ectomorphy explained BMD in the endurance-trained females in the femoral neck (21.3%) and in the lumbar spine (20.9%). We can conclude that from the body composition parameters, LBM is a powerful predictor of BMC and BMD. From the anthropometrical parameters measured, lower body parameters are the most important. Somatotype components (ectomorphy) had a relationship with BMD only in the endurance-trained group. There are some differences that depend on the specific physical activity field. In the endurance-trained group, the anthropometry is more important than in the strength-trained group.