Determinantes da capacidade de endurance ao exercício de membros superiores (relação potência duração) em pacientes com doença pulmonar obstrutiva crônica

Abstract

Recently the critical power (CP) has been used to evaluate the lower limbs (LL) endurance in patients with chronic obstructive pulmonary disease (COPD). Objective: To determine the upper limbs CP in COPD patients. Methods: Eight COPD patients (FEV1: 45.1 ± 1.2% of predicted) and seven healthy subjects were assessed. Four constant workload tests of upper limbs (100-120%, 90% e 80% of peak load and CP + 5 - 20%) were performed after an arm incremental test. The metabolic and ventilatory analyses were measured in all tests. The inspiratory capacity (IC) was performed before and immediately after each test. The CP was determined by the linear regression analysis among the tests with constant workload and the inverse time and it was confirmed in a new test. Results: There were no significant differences in the upper limbs CP workload comparing patients and controls [30.2 ± 12.7 W (59.8 ± 11.4% of the exercise peak) and 42.2 ± 16.7 W (66.7 ± 9.3% of the exercise peak, respectively]. The VO2 values reached in CP were lower in the COPD group than controls (0.79 ± 0.28 L/min vs 1.20 ± 0.37 L/min, respectively). The patients presented with dynamic hiperinsuflation and an important reduction of ventilatory reserve in all tests, including the CP test. Despite the ventilatory limitation, all patients reached the 20 minutes of the duration on the CP test. Conclusion: The present study confirms the hypothesis that the determinants of the upper limbs power-duration relationship in COPD patients are similar to the lower limbs already described in the literature.