Efeito da ingestão aguda de cafeína no desempenho físico, variabilidade e recuperação da frequência cardíaca em pacientes com DPOC.

Abstract

Chronic obstructive pulmonary disease (COPD) is characterized by dyspnea and exercise intolerance. The characteristic of the disease trend to become the patients sedentary, and triggering a deconditioning cycle. In other populations, caffeine (CAF) has showed to be an ergogenic resource, however, there are no studies in COPD. Therefore, the aim of this study is to verify the influence of CAF in exercise tolerance, heart rate variability (HRV) and heart rate recovery (HRR) in patients with COPD. Ten patients with previous COPD diagnosis were invited, in which each patient performed five visits to laboratory. In first visit, the participants answered questionnaires and were measured the anthropometrics, HRV, six-minute walk test and performed one incremental test to familiarized to ciclossimulador. In second and third visits, they performed incremental test with CAF ingestion (5 mg.kg-1 ) or placebo (PLA) (cellulose). In fourth and fifth visits, they performed constant load test with 60% to maximal power in PLA incremental test, but with CAF or PLA ingestion. During and after the tests, heart rate (HR) and peripheral oxygen saturation were measured. Time to exhaustion, HRV and HRR variables in both tests were recorded. Additionally, five patients were invited to perform a pulmonary function test with CAF ingestion, to verify bronchodilator effect of the CAF. An increase, but not significant, was observed in the time to exhaustion of 0.9% in the incremental test and 12.1% in the constant load test (p > 0.05). There was not significant difference between the autonomic variables, with the exception of the ΔHR60s, which was lower in the CAF condition during the constant load test, compared to the PLA condition (PLA = 15.3 ± 8.0bpm vs CAF = 11.4 ± 7.3bpm; p = 0.02). There was no effect of caffeine on forced expiratory volume in 1s (FEV1) (p > 0.05), and caffeine did not change the behavior of peripheral oxygen saturation during the constant load test (p >0.05) and delta of maximal tests did not correlate with the of ΔFEV1 (p >0.05). These findings suggest that caffeine ingestion did not have an ergogenic effect in COPD patients, because a lack of effect in variables of the respiratory system, although is safe in autonomic aspect.