Aerobic exercise at night has been shown to be more beneficial for regulating blood pressure in elderly hypertensive individuals than morning workouts. A study conducted at the School of Physical Education and Sports at the University of São Paulo (EEFE-USP) found that the reason for this is related to better regulation of a mechanism that compensates for sudden changes in blood pressure, known as baroreflex sensitivity.
“There are multiple mechanisms for regulating blood pressure, and although morning training brought benefits, it was only evening training that provided improvements in short-term blood pressure control – improving baroreflex sensitivity. This is important because, in addition to baroreflex control triggering positive effects on blood pressure control, there is no medication available to modulate this mechanism,” Leandro Campos de Brito, author of the article, told Agência FAPESP. published in The Journal of Physiology.
The work is the result of Brito’s postdoctoral project, supported by FAPESP and supervised by EEFE-USP professor Cláudia Lúcia de Moraes Forjaz.
In the experiment, 23 patients diagnosed and medicated for hypertension were divided into two groups: morning or evening training. Over the course of ten weeks, both performed 45-minute exercise bike workouts at moderate intensity, three times a week.
Important cardiovascular parameters, such as systolic and diastolic blood pressure (blood pressure in the vessels) and heart rate (heartbeat), were analyzed after ten minutes of rest. Data were collected before and at least three days after the volunteers completed the ten weeks of training.
In addition, the researchers monitored mechanisms of the autonomic nervous system – which works involuntarily, controlling heartbeats and blood pressure, for example – such as muscle sympathetic nerve activity (which regulates peripheral blood flow through the contraction or relaxation of vessels in muscle tissue) and sympathetic baroreflex sensitivity (assessment of blood pressure control via changes in muscle sympathetic activity).
Those who trained at night showed improvements in the four aspects analyzed: systolic and diastolic blood pressure, sympathetic baroreflex sensitivity and muscular sympathetic nerve activity. Those who trained in the morning did not have a reduction in muscular sympathetic nerve activity, nor an improvement in systolic blood pressure or sympathetic baroreflex sensitivity.
“Evening training was more effective in promoting cardiovascular autonomic improvement and blood pressure reduction. This can be partially explained by the improvement in baroreflex sensitivity and the reduction in muscle sympathetic nerve activity, which were greater at night. For now, we only know that baroreflex control is decisive – at least from a cardiovascular point of view – for evening training to be more beneficial than morning training, as it is what triggers the other benefits analyzed.
However, we still need to make a lot of progress in this understanding,” explains Brito, who is currently a professor at the Oregon Institute of Occupational Health Sciences at Oregon Health & Science University, in the United States, and continues to investigate the issue through studies on the circadian rhythm.
The researcher emphasizes that baroreflex control regulates each heartbeat and controls the body’s autonomic activity. “It is a mechanism that is linked to sensitive fibers and deformations in the walls of the arteries, which are located in specific locations, such as the aortic arch and the carotid body. Thus, when pressure drops, this region sends information to the area of the brain that controls the autonomic nervous system, which in turn sends information back to the heart so that it beats faster and to the arteries so that they contract more strongly. If pressure increases, it sends information to the heart to beat more weakly and to the arteries to contract less, thus modulating blood pressure beat by beat,” he explains.
In study Previously, the group of researchers from USP demonstrated that aerobic training performed at night induces a greater decrease in blood pressure than morning training in hypertensive men.
In other workthe more effective response of night training in reducing blood pressure was also accompanied by a greater decrease in systemic vascular resistance and systolic blood pressure variability.
“Replicating results obtained in previous studies and in different groups of patients with hypertension, associated with the use of more precise techniques to assess the main outcomes, strengthens our understanding of the greater autonomic benefit of aerobic exercise performed at night in patients with hypertension. This may be particularly important for individuals resistant to drug treatment,” he says.
The article Evening but not morning aerobic training improves sympathetic activity and baroreflex sensitivity in elderly patients with treated hypertension can be read at: https://physoc.onlinelibrary.wiley.com/doi/10.1113/JP285966#support-information-section .
This content was originally published in Aerobic exercise at night brings more benefits for elderly people with high blood pressure on the CNN Brasil website.
Source: CNN Brasil
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