Análise do desempenho, respostas ventilatórias e metabólicas, recrutamento e oxigenação muscular em indivíduos com Doença Pulmonar Obstrutiva Crônica durante o six-minute pegboard and ring test

Abstract

This present thesis has a result three studies: Study I - the aim of this study was to verify whether hand grip strength and endurance, body composition and anthropometry variables influence the performance of the six-minute pegboard and ring test (6PBRT) in COPD subjects. Thirty-three subjects with COPD and thirty-two healthy controls subjects were evaluated. Both groups were submitted to the assessment of anthropometry variables, body composition by dual-energy X-ray absorptiometry, hand grip strength and endurance tests (HGST and HGET). The HGET was performed with 50% of HGST score, with cadence of 20/min, and the endurance time (TE) was determined. Subjects with COPD had lower performance in 6PBRT and lower ET in HGET, with a strong correlation between ET and performance in 6PBRT. In addition, ET and upper limbs (UL) lean mass explained 54% of the variance in the 6PBRT. The correlations between the majority of body composition variables with the performance in 6PBRT were moderate (from -0.36 to -0.43) for COPDG. With the results obtained we conclude that the performance in 6PBRT seems to be more related to UL muscle endurance than to UL muscle strength in subjects with COPD. In addition, the upper limb weight seems to impair the performance of the test. Study II - the aim of this study was to verify the physiological responses during unsupported UL activities, represented by the 6PBRT, in subjects with COPD. Additionally, we compared these responses during the 6PBRT with healthy subjects in order to understand the intolerance to this type of exercise by subjects with COPD. Twenty-eight subjects with COPD and 27 healthy controls were assessed. The 6PBRT was performed with simultaneous evaluation of gas analysis (ventilatory and metabolic variables), as well as obtaining cardiovascular variables, pulse oximetry and sensation of dyspnea and fatigue. The individuals with COPD presented lower performance in 6PBRT, with higher ventilatory demand and oxygen consumption per ring moved during the test, presented higher dyspnea value and lower SpO2 value at the end of the test, besides the behavior of ventilatory and metabolic variables was of slow onset and of greater magnitude compared to healthy individuals. We conclude that subjects with COPD have higher values of ventilatory demand and oxygen consumption per ring moved in 6PBRT. In addition, the metabolic responses are larger in magnitude, however, apparently slowed at the beginning of the test, when compared with healthy subjects. These results may justify the lower performance presented by individuals with COPD. Study III - The aims of this study were to quantify the electrical activity and oxygenation of inspiratory and UL muscles; and to investigate whether electromyographic manifestations of muscle fatigue is related with UL function assessed by the six-minute pegboard and ring test (6PBRT) in COPD subjects and healthy subjects. Thirty subjects with COPD and 34 healthy controls were assessed. The 6PBRT was performed with simultaneous assessment of electromyography, near infrared spectroscopy and gas analysis. Individuals with COPD had a worse performance (number of rings) in the 6PBRT, with higher ventilatory demand and RMS amplitude of the sternocleidomastoid muscle (SCM), lower value for oxyhemoglobin and total hemoglobin in the intercostal (IC) muscles. We conclude that the findings of this study indicates that the 6PBRT is performed at higher electrical activity in the accessory inspiratory muscles, like SCM and lower oxygenation profile in IC by individuals with COPD when compared to healthy controls, however without muscle fatigue signs. These findings suggesting that the higher ventilatory demand presented in the COPD group could have contributed to the worst performance in this group; without signal of peripheral muscle limitation.