Análise da complexidade do torque extensor do joelho na síndrome da fragilidade

Abstract

Frailty syndrome is associated with a decline in the complexity of biological signals. The interactions between neuromuscular system components result in complex structures of torque, which can be simplified in the presence of frailty syndrome, leading to decreases in functional capacity. The aim of this study was to evaluate the complexity of submaximal isometric knee extensor torque in frail, pre-frail, and non-frail older adults. A cross-sectional study was conducted. Forty-two older adults were divided into three groups: non-frail (n= 15), pre-frail (n= 15), and frail (n= 12). The data collected included: body composition, five times sit-to-stand test, walking speed, and isometric knee extensor torque at 15, 30, and 40% of maximal voluntary contraction (MVC). The knee extensor torque variability was evaluated from coefficient of variation, and the torque complexity was evaluated from the analysis of approximate entropy (ApEn) and sample entropy (SampEn). The ANOVA two-way analysis of variance with repeated measures and the Holm-Sidak post hoc were used to test differences between groups and force levels. The significance level was fixed at 5%. The frail group presented a reduction in body weight, lean mass in the dominant leg, peak torque value and worse physical performance (five times sit-to-stand test and walking speed). In addition, the frail older adults presented reduced torque complexity in relation to the non-frail group. Although all groups showed an increase in torque complexity with increased force levels. In conclusion, torque complexity is reduced in the presence of frailty syndrome.