Measuring blood pressure is a routine test for our client review and screening process with all Exercise Physiology clients and gym members at Inspire Fitness.
We do this health check routinely because in Australia, high blood pressure, otherwise known as hypertension, is responsible for over 40% of cardiovascular disease.
Over 30% of all Australians have hypertension, and 68% of those are uncontrolled. Uncontrolled means the individual does not know they have high blood pressure, and it is not medicated (1).
By measuring your blood pressure, we are ensuring you are safe to exercise and can prescribe the right intensity for your exercise program.
What is Blood Pressure?
When measuring blood pressure, we are assessing pressure in your arteries during two phases of the heartbeat: the contraction phase and the relaxation phase.
You might recall being given two numbers representing your blood pressure: a high number and a low number.
These numbers are expressed in millimetres of mercury.
The high number is your systolic blood pressure. This is the pressure your blood puts on the walls of your arteries when your heart contracts. As such, this is the pressure of your blood within your arteries during the contraction phase of your heart.
Alternately the low number is the pressure your blood puts on the walls of your arteries when your heart is NOT contracting. This is the arterial pressure between contractions and is called diastolic blood pressure.
Factors Influencing Blood Pressure Measurement
There are two main factors which are influencing the measurement of your blood pressure.
Firstly, the strength of your heart (muscle) contraction. This effects how much blood the heart can it can push out with each beat.
Secondly, the pressure the walls of your arteries and arterioles apply back against the blood.
The strength of your hearts ability to contract is cardiac output, and it’s made up of your heart rate, and how much blood can be ejected from the heart with each beat, called stroke volume. They are multiplied together to make cardiac output.
The pressure the walls of your arteries apply against the blood moving through them is what we call total peripheral resistance.
Arteries and arterioles have smooth muscle in them, so they can make their pipes wider or narrower, whichever of those is needed at the time.
The higher the total peripheral resistance, the harder the heart must work in terms of cardiac output to overcome it. This is what happens in hypertension.
Medication Treatment of Hypertension
If you have been diagnosed with hypertension, you most likely have been given a combination of medications to adjust it. These are angiotensin converting enzyme inhibitors (ACE inhibitors), calcium channel blockers, and diuretics.
Rarely but occasionally is beta blockers prescribed now, unless there is another cardiovascular condition that needs managing.
ACE inhibitors modify the total peripheral resistance by affecting the smooth muscle in arteries, and cause them to vasodilate, so get wider.
This in turn decreases total peripheral resistance and so blood pressure. Calcium channel blockers affect all muscle, because calcium is part of the chemical cascade that allows muscle to contract. By doing this, it affects that smooth muscle, but also the ability of the heart to power stronger contractions, which affects stroke volume.
Diuretics alter blood volume, which affects the amount of blood returning to the heart (venous return) and venous return can also affect stroke volume. When venous return goes up, it causes cardiac output to go up to keep the blood moving. Beta blockers supress heart rate, by affecting the nervous conduction system of the heart.
These medications generally do not affect your ability to exercise, in fact make it safer for you to do so. The one exception to that is beta blockers, which by suppressing heart rate does decrease your tolerance to exercise and is a main reason why beta blockers are not really used any more for blood pressure management.
Exercise in the Treatment of Hypertension
How can exercise manage hypertension?
When you begin moving and exercising, your body requires more oxygen in the working muscles. Your body sends a message to the brain demanding more oxygen to your working muscles. Your brain responds with a message to increase cardiac output.
In response to your brains message your heart rate increase to supply more blood (and oxygen) to the working muscles. (i.e. higher heart rate during exercise)
Where your muscles aren’t working or required during an exercise bout, your brain sends a different message to constrict blood vessels (vasoconstriction) to reduce blood supply to the ‘non-working muscles’.
In the working muscles, the blood vessels dilate (vasodilation) to decrease the peripheral resistance and help more blood flow and oxygen get to where it is needed.
This all means that more blood flow is enabled to move around the body. This extra blood flow in turn increases the blood returning back to the heart.
This increase in blood flow returning to the heart puts a bigger stretch on the receptors in the right atrium (chamber of your heart) , which in turn triggers the heart to increase stroke volume and subsequently increase cardiac output.
Over time, this causes a training effect. As your body becomes accustomed to the training workload with repetitive exercise, your body adapts by increasing your stroke volume.
With a higher stroke volume your heart rate can lower at the same relative work output. This is achieved because your total cardiac output is increased with the increased stroke volume.
At the periphery, the muscles get better at extracting oxygen, and the smooth muscle in the arteries improves so total peripheral resistance goes down.
Moderate or high intensity interval training have shown to have the biggest decreases in blood pressure, particularly in people with hypertension (2-7).
It has been shown in research even 5 minutes of moderate intensity exercise will trigger a post exercise blood pressure lowering effect, which can last up to 22 hours. Imagine if you did that each day?
Over time, up to 12 weeks, we can see decreases in the systolic blood pressure of up to 22mmHg, and in diastolic blood pressure of up to 8mmHg (2, 3, 5-8). These are significant numbers.
Does Strength Training Treat Hypertension?
There is not as much research conducted on the impact of strength training in the treatment of hypertension.
The research does suggest that by combining strength session with short bursts of cardiovascular exercise is the best treatment for hypertension.,
This occurs because the cardiovascular exercise offsets the short-term increase in blood pressure which occurs during strength training (1, 8, 9). This is even doing lower intensity resistance training like resistance bands, not heavy weights (8).
Other things to consider are that holding your breath or using Valsalva type techniques will elevate your blood pressure. The research shows that arm strength training causes higher blood pressure changes than legs or whole-body exercises (1).
For those of you with hypertension, you have a unique opportunity to elicit beneficial changes into your blood pressure through a combination of cardiovascular exercise and strength training.
Talk to an Accredited Exercise Physiologist at Inspire Fitness today about how a tailored exercise program can assist you with control of your blood pressure.
References
Sharman JE, Smart NA, Coombes JS, Stowasser M. Exercise and sport science australia position stand update on exercise and hypertension. Journal of Human Hypertension. 2019;33(12):837-43.
2. Bahmanbeglou NA, Ebrahim K, Ahmadizad S, Maleki M, Nikpajouh A. Short-Duration High-Intensity Interval Exercise Training Is More Effective Than Long Duration for Blood Pressure and Arterial Stiffness but Not for Inflammatory Markers and Lipid Profiles in Patients with Stage 1 Hypertension. Journal of Cardiopulmonary Rehabilitation and Prevention. 2019;39(1):50-5.
3. Eun-Ah J, Kyoung-Im C, Do-Sun L, Ji-Hyun C, Jung-Jun P. Effects of interval training on blood pressure and endothelial function in hypertensive patients. International Journal of Applied Sports Sciences. 2018;30(1):50-61.
4. He LI, Wei WR, Can Z. Effects of 12-week brisk walking training on exercise blood pressure in elderly patients with essential hypertension: a pilot study. Clinical and Experimental Hypertension. 2018;40(7):673-9.
5. Ishikawa-Takata K, Ohta T, Tanaka H. How much exercise is required to reduce blood pressure in essential hypertensives: a dose–response study. American Journal of Hypertension. 2003;16(8):629-33.
6. Molmen-Hansen HE, Stolen T, Tjonna AE, Ekeberg IS, Tyldum GA, Wisloff U, et al. Aerobic interval training reduces blood pressure and improves myocardial function in hypertensive patients. European Journal of Preventive Cardiology. 2012;19(2):151-60.
7. Oliveros MJ, Gaete-Mahn MC, Lanas F, Martinez-Zapata MJ, Seron P. Interval training exercise for hypertension. Cochrane Database of Systematic Reviews. 2017.
8. de Oliveira SN, Pereira Moro AR, Polito MD, Helena de Jesus J, de Souza Bezerra E. Effects of Concurrent Training with Elastic Tubes in Hypertensive Patients: A Blind Controlled Randomized Clinical Trial. Experimental Aging Research. 2020;46(1):68-82.
9. Ruangthai R, Phoemsapthawee J. Combined exercise training improves blood pressure and antioxidant capacity in elderly individuals with hypertension. Journal of Exercise Science & Fitness. 2019;17(2):67-76.