The lead author of the study was Michael Wheeler, BSc (Hons.), who is a PhD candidate at the Physical Activity and Behavioral Epidemiology Laboratories, Baker Heart & Diabetes Institute, Melbourne, Australia. He is enrolled in the PhD Program through the School of Sport Science, Exercise and Health at The University of Western Australia in Perth.
As per the AHA and American College of Cardiology (ACC) Guidelines, a blood pressure
(BP) value of 130/80 mm Hg and above is considered as high blood pressure
There were two objectives of the study, which included the following:
- To find out whether the beneficial effects of morning exercise on BP were negated by long periods of sitting throughout the day in elderly, overweight or obese men and women
- To find out whether the benefits of morning exercise on BP could be enhanced by taking short walking breaks in-between sitting
It should be noted that conventionally, the health effects of exercise and sedentary behavior have been studied separately. However, the present study was conducted to find out whether there was a combined effect of these behaviors on blood pressure.
Salient Features of the Study
- The study participants consisted of men and women aged between 55 to 80 years
- There were a total of 67 participants - 32 men and 35 women
- All the participants were either overweight or obese
- The study was conducted in a controlled sports laboratory environment
- All the participants consumed the same standard diet, prior to and during the experiment
- BP and adrenaline (epinephrine) levels were measured every eight hours
The participants were asked to perform periods of exercise and sitting. The exercise consisted of walking on a treadmill at moderate intensity. The following three schedules of exercise and sitting were performed, each separated by a period of six days:
- Continuous sitting for eight hours
- Sitting for one hour before 30 minutes of exercise, followed by continuous sitting for 6.5 hours
- Sitting for one hour before 30 minutes of exercise, followed by sitting for 6.5 hours, which was interrupted every 30 minutes by 3 minutes of moderate intensity walking
- The average BP, especially systolic BP was reduced in both men and women who exercised in the morning, compared to when they did not exercise
- In women, the average systolic BP decreased significantly when they combined morning exercise with short breaks between sitting during the day
- In men, the average systolic BP was not influenced by taking short breaks between sitting during the day
Wheeler says "For both men and women, the magnitude of reduction in average systolic blood pressure following exercise and breaks in sitting, approached what might be expected from antihypertensive medication in this population to reduce the risk of death from heart disease and stroke. However, this reduction was greater for women."
The research team could not explain the underlying reason for the observed gender difference in the variation of the average systolic BP in response to exercise and sitting.
The gender difference observed could be due to differences in the levels of adrenaline, which is a stress hormone that fluctuates with the intensity of exercise. It could also be due to the fact that all the women were post-menopausal and therefore, at a higher risk of cardiovascular disease (CVD). Interestingly, other studies have reported that taking short breaks between sitting periods improves BP levels in individuals with a higher risk of CVD. Therefore, this could be a plausible explanation for the observed gender difference.
It can be concluded that the benefits of morning exercise on BP can be enhanced by avoiding prolonged sitting for long periods of time throughout the day. Moreover, future studies should specifically focus on testing for gender differences in BP with short breaks in sitting alone.
In this regard, Wheeler says "Having the study participants begin with exercise was intentional, because we wanted to focus on the novel aspect of combining exercise with breaks in sitting. However, it means that we cannot say for sure that breaks in sitting alone had no blood pressure lowering effect in men, as any effect could have been masked by the preceding effect of exercise."
With reference to whether the same benefits in BP would be applicable for a younger population and in those who are not overweight, Wheeler says "As the proportion of those who are overweight with higher blood pressure increases with age, adopting a strategy of combining exercise with breaks in sitting may be important to control and prevent the development of high blood pressure."
The study was funded by the National Health and Medical Research Council of Australia. Reference :
- Effect of Morning Exercise With or Without Breaks in Prolonged Sitting on Blood Pressure in Older Overweight/Obese Adults: Evidence for Sex Differences - (https://www.ahajournals.org/doi/10.1161/HYPERTENSIONAHA.118.12373)