Effect of Isometric Handgrip Training on Ambulatory Blood Pressure in Patients With Hypertension (ISOPRESS)

Meta-analysis studies have demonstrated that isometric training with handgrip promotes reductions in clinical blood pressure, reaching 8 mmHg for systolic blood pressure and 4 mmHg for diastolic. However, the effects of this training modality on ambulatory blood pressure, which is better discriminant of cardiovascular risk than clinical BP, remains uncertain. Thus, the ISOPRESS Network, consists of researchers from Brazilian institutions of education and research (Federal University of Santa Catarina, Federal University of Amazonas, Federal University of Sergipe, Federal Rural University of Pernambuco and Education and Research Center from Albert Einstein Hospital), will conduct a multi-center study to analyze the effects of isometric handgrip training on clinic and 24-h ambulatory blood pressure in patients with hypertension. For this, each research center will conduct a randomized controlled trial with medicated patients with hypertension, of both sex. The participants will be randomized into two groups: isometric handgrip training group (HBT: n = 25 per center) and control group (CG: n = 25 per center).Subjects assigned to the HBT will train three times per week, four sets of 2-min isometric contractions (using alternate hands) at 30% of maximal voluntary contraction, during 24 weeks. Subjects randomized to the CG will perform stretching and relaxation exercises three times per week, during 24 weeks. The evaluations will occur in three moments: baseline, post-12 and post-24 weeks. The primary outcome will be ambulatory blood pressure, while clinic blood pressure and cardiac autonomic modulation will be analyzed as secondary outcomes. For data analysis, in addition to descriptive statistics, two-way ANOVA for mixed model will be applied for within and between groups comparison. The level of significance that will be adopted is p<0.05.

All participants that will be assigned to supervised isometric handgrip training will train three times per week, during 24 weeks. They will perform a bout of isometric handgrip exercise: four sets of 2-min of isometric contractions (using alternate hands) at 30% of maximal voluntary contraction.

All participants randomized to control group will realize stretching and relaxation exercises, three times per week, during 24 weeks.

The participants randomized to the experimental group will perform 24 weeks of isometric handgrip exercise training, three times/week for 16 minutes with time to rest.

The participants randomized to the control group (active comparator) will perform 24 weeks of stretching and relaxation exercise training, three times/week for 16 minutes with time to rest.

For heart rate variability assessment, R-R interval will be obtained using a heart rate monitor (POLAR, RS 800CX), following the recommendations of the Task Force of the European Society of Cardiology and the North American.

Inclusion Criteria: Diagnosis of hypertension, controlled by up to three antihypertensive medications Blood pressure levels between 130 and 180 mmHg No high cardiovascular risk (no other cardiovascular, metabolic or pulmonary disease nor any signals or symptoms of these disease) Not engaged in a physical exercise program for at least six months Not present cognitive impairment (Montreal Cognitive Assessment ≥ 26 points) Exclusion Criteria: Adherence to less than 85% of training sessions Diagnosis of other cardiovascular diseases or diabetes during the course of the study Adherence to another supervised physical exercise program Change in medication class and/ or dose during the study Aggravation of the disease (i.e. blood pressure above 180 or use of four or more medications).