Asymmetry in body composition parameters of the upper and lower extremity among healthy Austrian women

Humans typically have bilateral symmetry, however, deviations from perfect symmetry can be observed. In the case of the upper extremities, mostly a right-biased asymmetry in the length or strength of the bones, but also lean body mass was reported. Regarding the lower extremities, the asymmetry patterns are weaker. The aim of this study is to analyze directional and cross-asymmetry in body composition parameters among healthy non-athletic women. In particular, it is hypothesized that body composition asymmetry patterns of the limbs change with increasing age. 584 Austrian women aged between 16 and 83 years were enrolled in the study. Data collection took place between 1995 and 2000 at the Menox outpatient department for the treatment of climacteric symptoms in Vienna. Bone mineral density (BMD), bone mineral content (BMC), lean mass, and fat mass was determined using dual-energy-x-ray absorptiometry (DEXA). Signed asymmetry was calculated for each body composition parameter of the upper and lower limbs. Right-sided symmetry dominated for lean mass, BMC, and BMD in the upper extremity. Asymmetry in the lower limbs was not as strong as in the arms, but a right-sided asymmetry was still observable. Fat mass showed the strong right-sided asymmetry of all measurements for the lower extremities in the whole sample. Contra lateral asymmetry of the extremities could be found in 37-45% of the sample for lean mass, BMD, and BMC. For fat mass, almost half of the sample displayed cross asymmetry. Significant associations between asymmetry patterns and age were observable for the fat mass of the upper extremities only. Participants younger than 30 years showed a significant left-sided asymmetry for fat mass in the upper extremities. However, this pattern changed around the age of 30 and shifted to a slight right-sided asymmetry. In general, the body composition of the upper and lower limbs showed distinct asymmetry patterns.