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Exercise alters baroreflex sensitivity in adolescents
There was a decrease in baroreflex sensitivity in adolescents 5 minutes after exercise regardless of exercise intensity, according to a study published in Experimental Physiology.
This may be driven by a lowered autonomic response, according to researchers.
At 60 minutes, they wrote, the ability of baroreflex sensitivity to regulate BP was restored after moderate-intensity exercise but not high-intensity exercise.
Ricardo Oliveira, PhD student at the Children’s Health and Exercise Research Centre at University of Exeter College of Life and Environmental Sciences in the United Kingdom, and colleagues analyzed data from 13 adolescent boys (mean age, 14 years) who were free from conditions that would affect their cardiac autonomic and vascular systems such as congenital heart disease, asthma and hypertension.
The participants attended four visits at least 3 days apart, which were completed within 4 weeks. During the first visit, participants were informed about the baroreflex sensitivity protocol and treadmill running. Baseline measurements such as brachial BP, images of the common carotid artery and breathing frequency were conducted on the other three visits.
After the visits, participants performed various conditions in a counterbalanced order on separate days: high-intensity interval exercise, moderate-intensity interval exercise and resting as a control. High-intensity interval exercise consisted of eight bouts of 1 minute at 90% of maximal aerobic speed with 75 seconds of active recovery, and moderate-intensity interval training consisted of between 10 bouts and 12 bouts of 1 minute of running at 90% of gas exchange threshold with 75 seconds of active recovery.
Heart rate and BP were monitored at baseline, 5 minutes and 60 minutes after the conditions.
Low-frequency gain decreased 5 minutes after bouts of high-intensity (P < .001) and moderate-intensity interval exercise (P = .002). These returned to baseline 60 minutes after exercise.
Arterial compliance increased 5 minutes after all exercise conditions (P = .048), which returned to baseline 60 minutes after exercise.
The interaction between low-frequency gain and arterial compliance decreased 5 minutes after high-intensity (P = .001) and moderate-intensity interval exercise (P = .004). These returned to baseline levels 60 minutes after exercise.
Both exercise intensities resulted in a reduction in mean arterial pressure 5 minutes after exercise. This remained decreased 60 minutes after high-intensity interval exercise.
“Our study is the first to characterize the mechanisms of post-exercise hypotension in youth, and the described vascular and autonomic adjustments may be linked to a better cardiovascular disease risk factor profile in this population,” Oliveira and colleagues wrote. “In youths aiming to avoid syncope following [high-intensity interval exercise], an active recovery or a cool-down period is encouraged to maintain an adequate pre-load and [stroke volume].” – by Darlene Dobkowski
Disclosure: The authors report no relevant financial disclosures.