BODY-COMPOSITION OF SPINAL-CORD INJURED ADULTS

The prevalence of diseases associated with obesity, such as cardiovasc ular disease and diabetes mellitus, is higher in the spinal card injur y (SCI) population. Specifically, the mortality rate for cardiovascula r disease is 228% higher in the SCI population. In addition, 100% of S CI individuals have osteoporosis in the paralysed extremities. These d iseases are related to physical activity level, the level of the spina l cord lesion, and time post injury. Physically active SCI men and wom en have above-average fat mass (16 to 24% and 24 to 32%, respectively compared with 15% for able-bodied men and 23% for able-bodied women), while sedentary SCI individuals have 'at-risk' levels of body fat (abo ve 25% and 32%, respectively). The proportions and densities of the 3 main constituents comprising the fat-free body (mineral, protein and w ater) are altered following SCI. Bone mineral content decreases by 25 to 50%, and the magnitude of reduction is dependent on the level, comp leteness and duration of SCI. Because of denervation resulting in skel etal muscle atrophy, total body protein reduces by 30%, and total body water relative to bodyweight decreases by 15% following SCI. Indirect methods based on 2-component body composition models assume constant proportions and densities of mineral, protein, and water in the fat-fr ee body. As a result, prediction equations based on 2-component models yield invalid estimates of fat and fat-free mass in the SCI populatio n. Therefore, future research needs to directly quantify the proportio ns and densities of the constituents of the fat-free body in the SCT p opulation relative to age, sex, physical activity level, level of the spinal cord lesion and time post injury, and to develop equations base d on multicomponent body composition models.