Strength training —practiced with moderate to vigorous load, two or three days a week— is a good strategy to decrease blood pressure. The conclusion is from a Brazilian study published in Scientific Reports magazine.
The mechanisms of blood pressure decrease through aerobic activities have been well studied. However, there are few investigations on strength exercise, such as the one conducted by researchers from Paulista State University (Unesp).
Under the coordination of Giovana Rampazzo Teixeira, professor at the Department of Physical Education at Unesp in Presidente Prudente, the group conducted a systematic review of the scientific literature on the subject with meta-analysis —a type of study considered the gold standard in terms of evidence. The objective was to verify the intensity, volume and duration of training that would guarantee the best results.
The research was carried out in collaboration with researchers from the University of Sao Paulo (USP) and was funded by FAPESP through three projects (21/14514-2, 20/15324-0 e 19/11924-5).
Cardiovascular diseases are the main cause of death in the world and arterial hypertension accounts for 13.8% of them. The condition is considered a problem when levels are above 140 millimeters of mercury (mmHg) systolic blood pressure and above 90 mmHg diastolic pressure. It is a multifactorial disease, triggered by habits such as sedentary lifestyle, poor diet, alcohol consumption and smoking.
It was already known that strength training was a therapeutic option, but there was, until then, little certainty about the most efficient protocols. With a sample of 253 participants, with a mean age of 59 years, the analysis was based on a series of controlled trials that evaluated the effect of training for eight weeks or more.
“We focused on establishing the volume and intensity that were sufficient to achieve a significant reduction in blood pressure values. On average, strength training performed in eight to ten weeks was sufficient for a reduction of 10 mmHg systolic and 4.79 mmHg diastolic stroke”, Teixeira tells Agência FAPESP.
The study showed that effective results were observed around the 20th training session and the beneficial hypotensive effects lasted up to 14 weeks even after the exercises were stopped —the so-called detraining phase.
“In clinical practice or even in the day-to-day life of gyms, professionals who are faced with a hypertensive subject will be able to use strength training as a non-pharmacological treatment for arterial hypertension, knowing what are the necessary variables for this to be achieved and always taking into account the person’s objectives”, explains the researcher.
Systematic analysis
For a long time, only aerobic training was indicated for the treatment of arterial hypertension and, therefore, molecular studies were almost entirely restricted to this modality.
“Recently, strength training entered the Brazilian Guidelines on Arterial Hypertension, but much still needs to be investigated so that we have more robust evidence. The perspectives of new studies are based on the molecular mediators that are responsible for this reduction in blood pressure at vascular and blood during strength training”, ponders Teixeira.
The systematic review was how researchers were able to analyze the breadth and robustness of evidence about the potential of strength training. Previous reviews verified that there was some effect, however, the work now published provides important additional evidence, such as load intensity, volume and weekly frequency. The researchers initially pooled 21,132 articles, of which 54 met criteria for full-text analysis. Of these, 14 were considered relevant for the review.
The most advantageous effect was observed in protocols with moderate to vigorous load intensity, above 60% of the load used for a maximum repetition, the most intense supported by the individual. That is, if the maximum load with which you can do a single repetition is 10 kilos, the most advantageous training load was above 6 kilos. Another important observation was to confirm that the frequency should be at least twice a week, maintained for at least eight weeks.
In clinical practice or even in the daily life of gyms, professionals who are faced with a hypertensive subject will be able to use strength training as a non-pharmacological treatment for arterial hypertension, knowing what are the necessary variables for this to be achieved and always taking into account consideration of the person’s goals
Most studies in the review covered people aged 60 to 68 years, with only two studies including a younger population (aged 18 to 46 years). Seven studies included patients of both sexes, in other seven studies the sample was composed only of women and one of the works included only men.
Looking at the subgroups, it was also found that the effect of the intervention is age-related. Those between 18 and 50 years had considerably greater hypotensive effects compared to the age group between 51 and 70 years. “In any case, strength training can be carried out at any age, because even in older people there are hypotensive benefits”, attest the researchers.
Future studies should unravel the cellular and molecular mechanisms responsible for the decrease in blood pressure as a result of strength training. What is known is that during physical activity there is an increase in heart rate, an increase in the diameter of blood vessels (vasodilation), greater blood flow and an increase in the production of nitric oxide (a compound with a vasodilator effect). In the long term, exercise promotes adaptations, such as a decrease in resting heart rate, improvement in cardiac efficiency and an increase in the maximum volume of oxygen that the body can absorb with each breath (VO2max).
Among the limitations highlighted by the researchers is the inclusion of patients who used antihypertensive drugs in 11 of the 14 studies, such as β-blockers, diuretics, calcium channel blockers and angiotensin-converting enzyme inhibitors. There is also the fact that some articles use men and women in the same intervention group, which prevents analysis according to gender.
The article “Strength training for arterial hypertension treatment: a systematic review and meta-analysis of randomized clinical trials” accessed here.
02/17/2023 – Equilíbrio e Saúde