As the name suggests, High Blood Pressure/Hypertension refers to persistent rise in overall blood pressure within the blood vessels. In more specific terms, the World Health Organization (WHO) defines High Blood Pressure/Hypertension as persistent elevation of Systolic Blood Pressure measured at or over 140mmHg, and Diastolic Pressure above or over 90mmHg. The measurements should be consistent at least 2 weeks apart.
How big is the problem?
According to estimates obtained by the World health Organisation, 1.13 Billion individuals are affected by the condition. However, about two-thirds of the affected population comes from low and middle income countries. By the year 2015, it was estimated that the condition affected 25 percent of men and 1/5ths of all women.
From a professional perspective, understanding this isn’t a problem. However, it leaves most people pricking their heads on what exactly it means. If you’ve ever been through a routine hospital check-up before, chances are that you’ve gone through a blood pressure test. The result typically comes in the form of a fractional value with a strange unit of measurement i.e. 120/80mmHg. The mmHg stands for Millimeters of Mercury, which is a unit of measurement for pressure. The values represent what’s known as Systolic Blood Pressure (the top value), and Diastolic blood pressure (the bottom value).
But what is Systolic and Diastolic Blood Pressure?
The term Systolic BP is derived from the word Systole, which generally refers to the phase where the Heart muscle contracts/squeezes to force the blood inside the Heart out towards the lungs and the whole body. The Heart can be viewed as a 2-way pump in the sense that it receives “used” blood from the rest of the body, then pumps it to the lungs to obtain new oxygen, and then receives it again before it’s pumped to the rest of the body.
A Little high school Heart Biology
If you recall your high school biology fairly well, you should be aware that the Heart is made of four chambers. These chambers act as conduits for the passage of blood, in addition to exerting pressure on the blood to propel it forward. Based on function and position, the chambers are called Left Atria, Left Ventricle, Right Atria and Left ventricle.
Blood enters the Heart through the Right Atrium before passing through a specialized valve(Bicuspid Valve) to fill the second chamber, known as the Right ventricle. A buildup of pressure in the chamber due to increased blood volume and contraction of the Heart muscle closes the valve and forces the blood from the Right ventricle towards the lungs through major blood vessels connecting the Heart and the Lungs.
The blood gets new Oxygen from the Lungs and re-enters the heart through the third chamber known as the Left Atrium. From this chamber, the blood passes through another set of valves within the Heart to occupy the fourth chamber, known as the Left Ventricle. Again, when the heart muscle contracts, blood is pushed from the Left ventricle towards the rest of the body through a major vessel known as the Aorta.
In short, the Heart muscle contracts to force blood to the rest of the body, before it relaxes to accommodate oxygenated blood from the Lungs as well as used blood coming from the rest of the body.
Types of High Blood Pressure/Hypertension
There are three main types of Hypertension based on the primary cause and behavior of symptoms.
1. Idiopathic: This type does not have one identifiable cause. It is the commonest, and accounts for over 95% of the affected population.
2. Secondary Hypertension: This typically comes in as a result of a pre-existing condition. It accounts for about 5-10% of the population.
3. Labile Hypertension: This is not necessarily persistent High blood pressure. It is characterized by isolated episodes of High Blood Pressure.
So what causes High Blood Pressure?
Although there’s been tremendous research efforts over the decades concerning the actual cause, Hypertension hasn’t been linked to one cause or pathway. Success has been limited to a number of risk factors which correlate with the incidence/occurrence of the disease. These include heredity, excessive sodium intake, Psychological stress, Obesity/overweight, excessive alcohol intake and drugs.
There are two key factors that determine the level of blood pressure within the blood vessels. These are Cardiac Output and Peripheral Resistance. The term Cardiac Output refers to the total amount of blood forced out of the Heart per minute whereas Peripheral resistance refers to the total resistance to the flow of blood in the major and smaller blood vessels (arteries and capillaries).
Expectedly, anything that causes one of these factors to rise causes the overall blood pressure to rise. For instance, conditions that cause the Heart muscle to contract/squeeze more forcefully can cause the overall Cardiac Output to rise. Good examples include Cardiac Muscle Dysfunctions, Kidney Disease and Heart valve abnormalities. Periodic overstimulation of the Heart muscle can cause the third form of HBP known as Labile hypertension. The overstimulation has been attributed to dysfunctions within the nervous system.
Peripheral resistance is also affected by a number of factors which mostly relate to physical properties of the arteries. These include decreased elasticity of the blood vessel walls, decreased cross sectional area, and increased blood viscosity. For instance, accumulation of fat and Cholesterol on the arterial walls reduces the size of the capillaries’ cross sectional area, which in turn increases the blood pressure. Other causes include Diabetes, Hyperthyroidism, pregnancy, brain tumors and Lead poisoning.
Numerous factors linked to the condition demonstrate the complexity of its development. The cause of HBP is best considered as an interplay of a variety of factors which tend to differ between individuals.
The general aim of treating HBP/HTN is to restore the blood pressure to normal levels, as well as eliminate or prevent related complications.
Anti-hypertensive drugs are a major part of the management in most settings. However, recent research has recommended lifestyle modification as a front-line intervention in most cases.
Weight-loss programs, Sodium intake restrictions, reduced alcohol consumption and aerobic exercise programs have significantly demonstrated effectiveness. These measures do not always indicate for elimination of prescribed medication. However, they often allow for a reduction of dosage, which also helps with eliminating related side effects.
Exercise and Hypertension: Does regular exercise help with HBP?
The short answer to this question is a resounding YES!
A lot of research has demonstrated the undisputable role played by regular exercise in favorable outcomes for the treatment of High Blood Pressure. With proper exercise, a drop of up to 10mmHg can be achieved, which is significant enough to allow termination or reduction of the prescribed medication for most patients.
Additionally, exercise has been demonstrated to reverse other complications such as Left Ventricular Hypertrophy. Although there is a lack of general consensus on the actual mechanism responsible for this effect, it is highly probable that the observed effects are due to the effects of exercise on multiple factors such as body fat composition, Heart muscle efficiency and Psychological well-being.
Exercise guidelines for Hypertension
- As pointed out earlier, Aerobic exercise has the capacity to decrease blood pressure by 10-20mmHg. Additionally they also decrease abnormal responses to physical exertion. Aerobic exercises are low intensity exercises performed over an extended period of time. These include brisk walking, jogging, cycling and swimming. When these are performed at a frequency of 30 minute sessions for at least 4 days/week, they can result in the observed changes.
- To keep things objective, you can easily track your exercise intensity by using your maximum Heart Rate. This can be estimated by subtracting your age from 220 (Maximum Heart rate: 220-age).
- Standard guidelines recommend exercise intensities of 40%-60% of the maximum Heart Rate for 4-6 times per week. However, the intensities can be increased to 85% of the maximum Heart Rate for previously active individuals. A lower frequency of 4 times per week is adequate in these cases.
The amount of time required to induce changes varies among individuals. Significant changes can be seen after several weeks to 6 months. However, training needs to continue in order to sustain the acquired changes.
- Consult the relevant health care professionals before taking up any routine. Doctors and Physiotherapists are best positioned to provide relevant advice and monitoring for safe exercise routines.
High Blood pressure shouldn’t be an excuse for a sedentary lifestyle.
From the evidence considered above, exercise isn’t just a matter of keeping fit. It is a huge part of treatment when it comes to High Blood Pressure. The guidelines discussed above should give you an idea on how you can go about getting started. All the best!