Exercise as it relates to Disease/Does a prescription of aerobic exercise and resistance training assist in controlling blood pressure in the older population?

What is the background to this research?
According to the Center for Disease Control and Prevention, almost 75% of American adults over the age of 65 had hypertension. The 'Australian Institute of Health and Welfare' reported that uncontrolled high blood pressure peaked at 47% (men and women inclusive) for those over 85 years of age. The worldwide hypertension trends showed that there was a doubling of people aged 30-79 with hypertension between 1990 and 2019.

With the older adult population increasing more rapidly than any other age population, understanding the causes and risks of high blood pressure, as well as devising ways in which it can be combatted, is important. Conditions including coronary artery disease, stroke and dementia can be somewhat attributed to an abnormally raised blood pressure.

While it is a well known and effective method for eliciting positive changes in body composition, at the time of this study, there was little known about the role that resistance training and aerobic exercise played in reducing the blood pressure of older adults. This study aimed to conclude whether the prescription of the physical activity measures would produce a positive reduction in blood pressure.

Where is the research from?
This study was published by the American Medical Association, particularly the Archives of Internal Medicine in 2005 and the participants Lived in the United States. Though it was a US-based study, the findings are applicable to Australians due to their relatively similar prevalence of hypertension. Another worldwide study conluded that the areas with the highest levels of uncontrolled blod pressure were Africa and Asia. Australia and the US were grouped into one category ('high income english-speaking countries').

The study was partly funded and supported by the Johns Hopkins School of Medicine, the Johns Hopkins Bayview Medical Centre and Johns Hopkins Bayview General Clinical Research. The funding partners had no apparent influence on anything in the study. As the research was funded by grants from the National Institutes of Health in both the Heart, Lung and Blood instutute and the Centre for Research resources, there was no underlying bias or conflict of interest.

Kerry J Stewart has had many published works with affiliation to Johns Hopkins Medicine. A number of these relate to Blood Pressure in patients with diabetes or other metabolic diseases. The remaining co-authors also had affiliatied works with Johns Hopkins Medicine, and all had published cardiovascular and blood pressure related material.

What kind of research was this?
Considered the 'gold standard' for observational research, and used to find relationships between an intervention and its effectiveness in a population, this study employed a Randomized Control Trial (RCT) method. RCT's are closely controlled, the participants are randomly placed into either the control or experiemental group, and for the results to be deemed statistically significant, they must allign with pre-determined values.

What did the research involve?
This trial employed 104 adults aged between 55 and 75 who each had untreated mild hypertension. Once informed consent was gained the participants underwent extensive screening. Examples of factors tested include:


 * Blood Pressure
 * ECG analysis
 * Body Mass Index
 * Blood Chemistry

The study was conducted between July 1, 1999, and November 30, 2003. The study was advertised in newspapers and initially gained great interest from the researchers' target population. Of those who responded to the advertisement, the majority were unsuitable for the study. The final trial comprised of 51 exercisers and 53 controls, each with resting BP at a level which correlated to either prehypertension or stage 1 hypertension. The exercisers were assigned a 3-session per week aerobic and resistance training schedule. The controls were advised to continue with a normal level of physical activity and diet. Participants had their blood pressure, arterial stiffness, body composition and aerobic and strength fitness tested at both baseline and 6-months (this would, in most cases, signify the conclusion of the study).

The methods by which the participants were selected were adequate for the purpose of the study. This was due to the visibility of the advertisement and the trial's effectiveness at using only suitable participants

What were the basic results?
The researchers emphasised that exercise in the older population elicited major health benefits including decreased BMI, weight loss, increased aerobic fitness and of course, decreased blood pressure. The findings are applicable to many older adults, and may be important in the prescription of exercise and subsequent treatment of hypertension. They were also consistent with what similar and more recent studies have concluded.
 * Diastolic blood pressure reduction was significantly greater in the exercise group compared to the control (P = 0.02)
 * Systolic blood pressure reduction was not statistically significant between the two groups (P = 0.67)
 * Participants in the exercise group (2.3kg) lost a signifcantly greater amount of body weight than the control group (0.5kg)

What conclusions can we take from this research?
The study concluded that older adults may be resistant to changes in systolic blood pressure due to the arterial thickening associated with ageing. While the authors also stated that the prescription of exercise lowered the diastolic blood pressure (DBP), this may once again be attributed to the thickening and stiffening of arteries.

Due to the increased arteriolar stiffening and associated increase in systolic blood pressure (SBP), the lowering of SBP due to the exercise intervention is important for devising ways of controlling overall blood pressure (BP).

A 2015 trial studied the effectivenes of exercise as a prevention strategy and treatment for adults with and without hypertension. It concluded that moderate aerobic exercise was able to assist in managing symptoms and elicited preventative properties for those yet to experience high blood pressure. Similarly to the 2005 study, it concluded that properly performed resistance training could lower both SBP and DBP. As this study focused only on adults, a study from 2020 confirmed that exercise was able to at reduce SBP and DBP, as well as treat hypertension in older adults.

Practical advice
It can be important for anyone who may be at risk of, or who currently has a high blood pressure, to be cleared by an accredited exercise professional before beginning exercise training. However, this does not apply to asymptomatic individuals in this age bracket, as normal exercise poses little risk of any adverse events occurring. This can reduce the risk of any major cardiovascular events taking place. It is also important that those who are cleared and wanting to participate in any kind of physical activity, know the risks associated with the exercise to be undertaken.

Further information/resources
For those who think they may be at risk of developing hypertension, or those who currently have high blood pressure and would like some more information, the below links offer some valuable advice and information:


 * https://www.heartfoundation.org.au/bundles/for-professionals/hypertension
 * https://www.cdc.gov/bloodpressure/index.htm


 * https://www.nhs.uk/conditions/high-blood-pressure-hypertension/