Overview

It is common knowledge that exercise and physical activity are absolutely critical for good physical, mental and cognitive health. They impact every single organ system, as well as endocrine glands, ensuring all of them work optimally. They also strengthen the immune system thereby reducing the risk of infection or disease, and prolonging lifespan. In this article, we will focus specifically on benefits of exercise and physical activity on heart-health, both at macroscopic and anatomical levels.

Cardiovascular conditions that can be remedied by exercise

There are various heart conditions that affect different aspects of the heart’s anatomy which includes the main arteries and veins, valves between chambers, muscles of the heart walls, and electrical signalling that ensures proper heart-rhythm. However, not all heart conditions can be corrected by exercise and physical activity (E&PA). Some of them will need implants or surgical interventions of some sort. So, we will only focus on those conditions that are positively impacted by E&PA.

• Coronary artery disease (CAD), also called coronary heart disease (CHD): This results from reduced blood-flow (myocardial perfusion) which leads to chest pain (angina), heart attack (myocardial infarction), and/or heart failure. These conditions account for nearly 33% of all cases of cardiovascular diseases.
• Cerebrovascular disease (CVD): Atherosclerosis is a condition in which cholesterol deposits in blood-vessels get hardened, and form what is called plaque. This plaque can reduce blood-flow. This can lead to CVDs such as brain-stroke and transient ischemic attack (TIA).
• Aortic atherosclerosis: When the atherosclerosis happens in the aorta which is the main artery that supplies oxygenated blood to the rest of the body, it leads to aneurysms (balloon-like bulges in the walls of blood-vessels, filled with blood) in the thorax and abdomen.
• Peripheral artery disease (PAD): When clots or plaque-deposits block blood-flow in blood-vessels of the arms and limbs, it causes PAD, which results in various complications.

Also Read: The Positive Impact of Regular Exercise in Elders

Benefits of Exercise on the heart

Broadly speaking, cardiovascular exercises like walking, jogging, swimming, aerobics, cycling and playing sports benefit the heart in the following ways:

1. Reduces blood pressure: E&PA uses various muscle-groups in the body, thereby regulating blood-flow all over the body and reducing blood-pressure.
2. Improves oxygenation: Exercise strengthens the muscles, so now they are drawing more oxygen from the blood. The lungs draw more air and impart more oxygen to the blood. As oxygen-levels in the blood rise, the heart which also requires oxygen-rich blood, works more efficiently now.
3. Maintains a healthy weight: Exercise burns calories and draws from sugar or fat deposits stored in the body. This leads to more lean muscle-mass and healthy weight.
4. Reduces stress: Among all stress-management techniques, E&PA is most efficient, leading to reduced stress, and hence reduced blood-pressure. Healthy levels of blood-pressure reduce wear and tear of the heart, helping it perform optimally at all times.
5. Improves HDL cholesterol levels: High-density lipoproteins (HDL) or good cholesterol help remove excess cholesterol in the arteries and move them to the liver where they are broken down. Cleaned-up arteries reduce the risk of atherosclerosis and CVD.

At the Microscopic level

Plasma Lipids and Atherogenesis

• Plasma Lipids refers to fat molecules present in the blood. It is found that people who indulge in endurance training have higher levels of high-density-lipoprotein (HDL) or good cholesterol and low levels of triglycerides, both of which indicate a reduced risk of CVD. However, these findings are also dependent on type of exercise, duration of exercise, intensity of exercise and diet consumed. Studies have shown that not just the levels of HDL but also the size of HDL and LDL molecules matter in determining the risk of CVD.
• Atherogenesis refers to the formation of plaque in people in atherosclerosis. It is found that people who exercise often have shown regression or delayed progression of atherosclerosis. Homeostasis refers to how the body responds to various changes that happen constantly, in order to keep certain body parameters constant. Studies have shown that E&PA directly affects homeostasis of the arterial walls in people with atherosclerosis. It was found that the arterial walls in such people showed reduced tendency to develop plaque deposits. This is due to various bio-chemical factors, explaining which would be beyond the scope of this article.

Also Read: The Benefits of Exercise

Insulin Sensitivity

As you are aware, insulin is required to convert blood-sugar to energy. Insulin pushes blood-sugar to various body-cells who consume the same, in order to create energy. In people with Type-2 diabetes, body-cells have developed a resistance to insulin and do not consume the sugar adequately thereby leading to a rise in blood-sugar. Insulin sensitivity is the opposite of Insulin resistance and indicates how efficient are body-cells in consuming blood-sugar in order to create energy.

Various studies have shown that E&PA improves insulin sensitivity in both types of people – insulin-dependent and non-insulin diabetics. Studies conducted on animals in laboratories have shown that exercise improves insulin sensitivity in skeletal muscle, adipose tissue and the endothelium, which are the major tissues that are responsible for insulin resistance in Type-2 diabetics.

Blood Pressure

Exercise requires the heart to perform at a higher level, that is, cardiac output must be higher during exercise to meet the additional demand for oxygen-rich blood. This increased cardiac output is achieved by increasing the heart-rate, as well as the cardiac stroke volume (quantity of blood pumped in each beat). Exercise precisely achieves this. During exercise, there is a temporary increase in vascular resistance (or tightening of muscles in the walls of blood vessels) in order to achieve a higher blood-pressure.

However, in the resting and ambulatory hours (when one is going about doing their normal activities and not exercising), blood-pressure is lower in people who exercise regularly than in those who do not. This consistent low blood pressure, when one is not exercising, combined with a healthy diet, lifestyle changes and behavioural changes are known to hugely reduce the risk of CVD.

Cardiac Adaptations

During exercise, there is excess pressure and volume of the blood to be handled by the heart, and this leads to hemodynamic stress in the heart. In people who exercise regularly, such stress cycles occur frequently. So, to normalize this stress and ensure the person enjoys good cardiac output during exercise, the heart undergoes physical changes in its shape and size, especially an increase in the thickness of the ventricular walls.

To achieve this incremental thickness, some of the heart-muscle-cells (called cardiomyocytes) increase in mass. The ability of the heart-muscles to contract is not affected, and may only be enhanced, after such a change in mass. This kind of morphological change (change in shape, size or form) is called adaptive remodelling of the heart, and is a healthy type of remodelling that the heart undergoes.

In contrast to this, there is an unhealthy type of remodelling called pathological remodelling as in the case of people who have hypertension (high BP) or aortic stenosis (narrowing of the aorta due to plaque deposits in it), there is constantly high blood-pressure. Over time, this can negatively affect the contraction function of the heart muscle, which increases the risk for heart attack.

Studies have shown that in people who exercise regularly, signalling pathways in the heart ensure there is adaptive and not pathological remodelling that happens.

Also Read: What are the benefits of doing cardio exercises like Running?

Blood and Vasculature

During exercise, the body requires more oxygen to be supplied through oxygen-rich blood, than during resting or ambulatory hours. This ensures the person is able to perform exercise better and not suffer fatigue. In people who exercise regularly, the demand for oxygen-rich blood-flow cycles is more than in those who do not exercise much.

So in response to this, the circulatory system also undergoes several small adaptations. For example, the tiny arteries (called arterioles) that supply blood to the skeletal muscles must undergo proper dilation or expansion during exercise. It is found that, over time, this vasodilatory capacity of the arterioles and small arteries increases. Further, newer arterioles or arteries are created by the body, which means, vascular density also increases.

The heart which has to pump harder during exercise, also needs a higher supply of oxygenated blood for its own functioning. Studies have shown that multiple bio-chemical mechanisms kick in, to ensure the heart has a higher supply of oxygenated blood in people who exercise regularly.

Studies have also shown that there is an adaptive response which ensures faster tissue repair during exercise, thereby preventing fatigue during exercise.

Outlook

It is not without reason that exercise is called the elixir of life. A healthy blend of cardiovascular exercises and strength training (resistance training/weight training) can ensure good health well into the old ages.

Before you start on an exercise regimen, consult your doctor so that he can rule out any contraindications (people with certain health condition for whom high-intensity exercise is forbidden) or special considerations (certain medications that are prescribed to the person which are known to affect blood-pressure, because of which exercise should only be low-intensity) do not apply in your case.

Reviewed by Dr Suresh S Venkita, Group Medical Director, Kauvery Hospitals

Kauvery Hospital is globally known for its multidisciplinary services at all its Centers of Excellence, and for its comprehensive, Avant-Grade technology, especially in diagnostics and remedial care in heart diseases, transplantation, vascular and neurosciences medicine. Located in the heart of Trichy (Tennur, Royal Road and Alexandria Road (Cantonment), Chennai, Hosur, Salem, Tirunelveli and Bengaluru, the hospital also renders adult and pediatric trauma care.

Chennai – 044 4000 6000 • Trichy – Cantonment – 0431 4077777 • Trichy – Heartcity – 0431 4003500 • Trichy – Tennur – 0431 4022555 • Hosur – 04344 272727 • Salem – 0427 2677777 • Tirunelveli – 0462 4006000 • Bengaluru – 080 6801 6801

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