Body composition and its relation to bone mass and fractures in an urban and a rural population

A higher incidence of fragility fractures in urban than in rural populations has been described. The present study included 954 randomly selected men and women between the ages of 40 to 80 years living in the cities of Malmö, an urban population, and Sjöbo, a typical agricultural community. Lean body mass (LBM) was estimated with a bioelectrical impedance method; bone mineral content (BMC) of the forearm was evaluated by single photon absorptiometry, and strength of the quadriceps, and hamstring muscles of the right knee, and hand grip were measured. The age-related difference in LBM between the ages of 50 to 80 were 7.8 kg in men and 2.9 kg in women. Urban men aged 60 and 70, and women aged 50 and 70 had a 1.8 to 3.7 kg lower LBM than rural subjects. One hundred women (17%) and 28 men (11%) had experienced fragility fractures. Women aged 70 with fragility fractures had 3.1 kg lower LBM than women without fractures, and the age-dependent difference in LBM was greater in the urban and rural women with fracture, than in women without fracture. LBM showed a higher correlation to BMC, in the range of 0.20-0.28, than the correlation between body weight and BMC. Quadriceps muscle strength was lower in the elderly age groups in both sexes, and a 40% decline was seen both in those from the highest and lowest quartiles of LBM. Use of LBM instead of body weight showed higher correlations to flexion strength of the knee and hand grip.(ABSTRACT TRUNCATED AT 250 WORDS)