This study aims to evaluate the autonomic and hemodynamic responses triggered by inspiratory muscle exercise in prehypertensive and hypertensive individuals. The reason that leads us to this study refers to clinical relevance for individuals with high blood pressure levels, since this type of exercise can act as a important nonpharmacological agent for arterial pressure control. In addition, this study aims to elucidate the mechanisms involved in cardiovascular responses to inspiratory muscle exercise and, consequently, provide safety in the prescription of these for this population.

This is a randomized clinical trial, consisting of a convenience sample of patients from the Cardiology Department of the University Hospital (UH) of the Federal University of Juiz de Fora (FUJF). The patients will be invited to participate in the study and will receive information regarding the objectives and procedures of the study. In case of agreement with their inclusion in the study, they will sign a free and informed consent form.

The entire experiment will be carried out in the Physical Evaluation Laboratory of the UH-FUJF, by the researchers previously trained in the application of the protocol. The stages of the experimental protocol will be divided into three days as described below.

1. 1st day of the experimental protocol (initial evaluation): medical historical, anthropometric evaluation, electrocardiographic monitoring at rest, evaluation of respiratory muscle strength and familiarization with the muscle training device. All volunteers will be instructed to refrain from taking caffeinated and alcoholic beverages for 24 h before the evaluation and to have a good night's sleep.
2. 2nd and 3rd days of the experimental protocol: all volunteers will be randomly assigned to two exercise sessions (ES): Sham IME (no load) and moderate intensity IME (40% of MIP). Initially, the volunteers will perform a 10-minute supine rest for heartbeat collection and subsequent calculation of heart rate variability (HRV), blood pressure and forearm blood flow measurements and evaluation of the baroreflex system. In sequence the ES will be conducted with continuous monitoring of blood pressure, heart rate and subjective perception of effort through the Borg Scale. Immediately and until one hour after the ES, it will be measured forearm blood flow, blood pressure, heart rate and evaluated the baroreflex system and HRV in order to investigate the acute effect of ES. The volunteers will be monitored using an equipment capable of evaluating the outpatient measurement of blood pressure and electrocardiogram for 24 hours in order to investigate the chronic effect of ES.

Inclusion Criteria:

• Clinical diagnosis of prehypertension (systolic blood pressure > 121-139 mmHg / diastolic blood pressure > 81-89 mmHg) and stage 1 hypertension (systolic blood pressure > 140-159 mmHg / diastolic blood pressure > 90-99 mmHg) with low to moderate cardiovascular risk
• Do not use drugs to control blood pressure levels
• Sedentary for at least 6 months

Exclusion Criteria:

• Cardiovascular or respiratory diseases
• Arrhythmias detected during electrocardiographic monitoring
• Inability to perform the proposed protocol