Acute Effects of Inspiratory Muscle Training on Peripheral Muscle Metabolism and Autonomic Response in COPD Patients

Condition(s) studied

Investigational drug(s) / intervention(s)

IMT-S (strength): Composed of 3 sets of 1 minute of maximum, deep inspirations, with 2 minutes of rest between sets, totaling 3 minutes of IMT. The initial load will be individualized according to the MIP, with the load equivalent to 60% of the MIP.

IMT-R (resistance): Composed of 3 sets of 2 minutes of maximum, deep inspirations, with 2 minutes of rest between sets, totaling 6 minutes of IMT. The load will also be individualized according to the MIP, with the load equivalent to 30% of the MIP.

Sham - IMT: Composed of 3 sets of 2 minutes of maximum, deep inspirations, with 2 minutes of rest between sets, totaling 6 minutes of IMT with a minimum load of 3cmH2O.

Study summary

The study will evaluate the acute effects of inspiratory muscle training (IMT) on peripheral muscle metabolism and autonomic response in patients with chronic obstructive pulmonary disease (COPD). This is a randomized, crossover study, with blinding of the evaluator and the researcher responsible for the statistical analysis. Participants will be divided into three groups at different times: TMI- strength (F), TMI to gain inspiratory muscle strength; IMT- resistance (R), IMT for improving inspiratory muscle resistance; and TMI sham. All participants randomized in the study will participate in the three groups, with a minimum interval of 48 hours between participation in each group. Randomization will determine the sequence of participation in the three groups for all participants.

For statistical analysis, an intention-to-treat approach will be used, and the groups will be compared using the Student's t test for continuous variables or the chi-square test for categorical variables. A split-plot ANOVA with repeated measures will be used for primary outcomes, and analysis of covariance will be conducted to identify differences between groups using baseline scores as covariates. Effect sizes and confidence intervals will be calculated using eta squared.

It is expected that IMT applied at different loads can promote effects on vascular function, peripheral muscle metabolism and the response of the autonomic nervous system in patients with COPD, which can greatly contribute to the understanding of the physiological effects of this therapy and support its prescription. as a therapeutic intervention in the rehabilitation of patients with pulmonary diseases.

Eligibility

Primary outcome measure(s)

• Peripheral vascular function and muscle metabolism — Up to four weeks
  Evaluated using Near Infrared Spectroscopy (NIRS). Tissue perfusion measurement will be performed using an arterial occlusion maneuver. After three minutes of rest to stabilize the initial measurements; \[tissue oxygen saturation (StO2) measured in percentage (%), oxyhemoglobin (HbO2) and deoxyhemoglobin (HHb) measured in mmHg\], the cuff will be inflated above 250 mmHg up to 280 mmHg , so that the blood flow is completely interrupted, being maintained for a period of five minutes, until the stabilization of the measurements. The variables obtained during the arterial occlusion maneuver will be: StO2 recovery time after occlusion, HHb variation during occlusion and StO2 variation during occlusion. The variables obtained during the exercise will be: variation of HHb and StO2, time to reach the lowest StO2, rate of deoxygenation and reoxygenation and walking economy in relation to HHb and StO2.
• Heart rate and R-R interval recordings — Up to four weeks
  Patients will be evaluated in the laboratory at 22 degrees Celsius (°C) with relative humidity between 50-60%. They should avoid stimulants, alcohol and exercise the day before the test and refrain from smoking or using bronchodilators for 6 hours before the test. An electrocardiogram will be recorded via Holter (CARDIOS™, Brazil) using a bipolar DII electrode, with three electrodes placed on the chest after asepsis and trichotomy. Holter software will provide time series data of heart intervals, analyzing heart rate variability (HRV) in both the time and frequency domains. In the time domain, indicators of sympathetic and parasympathetic activity will be calculated. In the frequency domain, the low, high and very low frequency bands will be evaluated, with the ratio between low frequency and high frequency, representing sympathovagal balance.

Trial sites (1)

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