Predição da massa livre de gordura e do índice de massa muscular por impedancia bioelétrica em homens com tetraplegia fisicamente ativos

Abstract

Individuals with cervical spinal cord injury (c-SCI) experience progressive loss of fat-free mass (FFM) due to decreased physical activity and neurological impairments because the function of spinal neuronal circuits below the level of injury is impaired. Therefore, there is a reduction in muscle strength and physical performance, characterizing sarcopenia, similar to what occurs in the elderly. The bioelectrical impedance (BIA) method is valid and accessible for predicting FFM in different population. The ground of the BIA method is based on the principle of constant hydration. However, individuals with c-SCI show important variations in hydration status, a fact that makes it difficult to use generalized predictive equations for FFM by BIA. Considering that the prediction of FFM in individuals with c-SCI is important to monitor changes in body composition and to support studies on sarcopenia, the present dissertation aims to: 1) test the agreement between the FFM values obtained by three different predictive equations by BIA and by dual-energy X-ray absorptiometry (DXA), 2) test the applicability of bioelectrical impedance vector analysis (BIVA) for this group; and 3) compare the use of the muscle mass index (SMI) from the FFM obtained by BIA and DXA for the diagnosis of sarcopenia in people with tetraplegia, considering different levels of physical activity (sedentary, active >150 minutes per week, and very active > 210 minutes per week). Able bodied individuals (n=23) and with c-SCI physically active (n=13) or inactive (n=10) participated in the study. Only the equation by Buchholz et al. showed agreement (coefficient of agreement=0.85) with DXA. Sarcopenia is a common disease after c-SCI and can be diagnosed using the SMI, which was tested in this group using the suggested equations for BIA and DXA. The use of the SMI-BIA to classify sarcopenia in sedentary c-SCI individuals resulted in substantial diagnostic agreement (Kappa=0.727) according to the Kappa coefficient. Buchholz et al. equation presented the best agreement, but this was not enough for this equation to be recommended for use in people with c-SCI and a specific equation for this population should be created. However, the use of cut-off points to diagnose sarcopenia from the SMI-BIA seems promising in sedentary people with c-SCI, necessitating further studies in people with c SCI that are physically active.