Health benefits of regular exercises

Health benefits of regular exercises

Exercise represents a major challenge to whole-body homeostasis and provokes widespread changes in numerous cells, tissues and organs in response to increased metabolic demand. (https://pubmed.ncbi.nlm.nih.gov/25417152/)

How does exercise improve cholesterol?

Cholesterol is an umbrella term used for different types of lipids (fat) in the blood. It is broadly divided into low density lipoprotein (LDL) i.e. the bad cholesterol, and high-density lipoprotein (HDL) i.e. the good cholesterol. 

High levels of LDL indicate surplus lipids in blood, which in turn increases the risk of cardiovascular complications. Studies have shown that LDL and lipoprotein (A) are more likely to stick to the arterial lumen leading to progressive plaque formation. This causes hardening and narrowing of the arteries which is commonly known as atherosclerosis and may precipitate in dangerous cardiac event. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3906547/).  The HDL cholesterol transports lipids back to liver for recycling and disposal. Hence high levels of HDL are indicative of a healthy cardiovascular system. Triglycerides in plasma are derived from fats eaten in foods or from other energy sources. An excess of triglycerides and very low-density lipoproteins (VLDL) are positively and independently associated with cardiovascular risks, even in individuals who have normal LDL values. 

There is a direct relationship between chronically elevated cholesterol levels (dyslipidemia) and coronary artery disease. 

Exercise appears to enhance the ability of skeletal muscles to utilize lipids as opposed to glycogen, thus reducing plasma lipid levels (https://www.mayoclinicproceedings.org/article/S0025-6196(12)01094-4/fulltext). The mechanism may include increase in lecithin-cholesterol acyl trans (LCAT) enzyme, which is responsible for ester transfer to HDL cholesterol which has been shown to increase following exercise training. Ferguson et al (1998) reported that 1100 kcal of energy expenditure is required to elicit increases in HDL cholesterol that coincide with significant increases in lipoprotein lipase activity (https://pubmed.ncbi.nlm.nih.gov/9729596/). The process of cholesterol removal is known as “reverse cholesterol transport”. This process removes cholesterol from circulation for disposal as a result of increase in LCAT and reduction of cholesterol ester transfer protein (CETP) following acute and chronic exercises. This increased enzymatic activity increases the ability of muscle fibers to oxidize fatty acids originating from plasma, VLDL cholesterol or triglycerides. 

How does exercise improve heart health? 

Exercise increases mitochondrial biogenesis in adipocytes, skeletal muscle myocytes and cardiomyocytes increasing aerobic respiration within these tissues. Additionally, exercise improves oxygen delivery throughout the body through vasodilation and angiogenesis protecting against ischemia-reperfusion injury in the heart. Mitochondrial biogenesis augmentation is likely due to enhanced activation of AMP-activated protein kinase (AMPK) and subsequent increase mitochondrial PGC-1α expression. Exercise also increases the ability of mitochondria to oxidize fatty acids thus increasing the capacity to synthesize ATP. 

Exercise training induces vascularization in several tissues including cardiac tissue.  This helps reduce the likelihood of ischemic cardiac event. These adaptations are mediated through increased expression of vascular endothelial nitric oxide synthase (eNOS). Exercise increases the intensity of physiological shear stress, inducing the shear-stress dependent activity of c-Src in endothelial cells and increasing expression eNOS. In the vascular endothelium, eNOS catalyzes the production of nitric oxide (NO) which causes vasodilation, inhibits platelet aggregation and leukocyte adhesion to vessel walls, thus reducing the onset of atherosclerosis, thrombosis, ischemia or other fatal cardiac events. 

Exercises causes increase in heart rate and stroke volume. When done regularly, moderate to vigorous exercise strengthens heart muscle. This improves the heart`s ability to pump blood to all body parts including lungs which improves blood oxygen carrying capacity. As a result, there is improved circulation and oxygenation of skeletal muscles. Skeletal muscles can act as secretary organs by stimulating the production, secretion and expression of specific myokines after contraction. Myokines are chemical messengers that function in an autocrine, paracrine or endocrine manner to influence cross talk between different organs including skeletal muscles, liver and adipose tissue. They are of great interest with regards to cardiovascular health because the well-known protective actions of exercise on cardiovascular function are at least partially mediated by increased secretion of myokines. Some myokines that impact cardiovascular health include Interleukin-6, myonectin, Follistatin like 1 and Neuron Derived Neurotropic Factor. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6557987/#:~:text=Exercise%20Improves%20Vasculature%20and%20Myocardial%20Perfusion&text=In%20the%20heart%2C%20the%20increase,nitric%20oxide%20synthase%20(eNOS). 

Several studies have investigated and proved that in patients with cardiovascular disease, exercise improved endothelium-dependent vasodilation, increased ejection fraction, improved exercise tolerance, quality of life and reduced cardiovascular cause-related mortality. 

What are the benefits of exercises on the Musculo-skeletal system?

A huge number of studies have proved significant benefits of regular exercises on the bone and muscle structure and function. This becomes more evident in the aging population where the decline in Musculo-skeletal strength is relatively rapid, thus increasing the risk of loss of balance, falls and fractures. 

A clinically meaningful objective of the management of osteopenia and osteoporosis is the prevention of fracture occurrence. Hence, preservation of bone strength and reducing the rate of falls are ideal targets of intervention. Exercise therapy has proven favorable effects on both bone strength and reduction in fall risks, thus the first choice of intervention in the management of osteopenia and osteoporosis. 

Sarcopenia is an age-associated muscle condition which literally means “lack of flesh”, that accelerates after the age of 50. Limitations to perform the activities of daily living increase due to this condition. Sarcopenia is also known to reduce life expectancy in comparison to those with normal muscle strength.

Resistance exercise is considered and important strategy for preventing muscle wasting because it stimulates muscle hypertrophy and increases muscle strength by shifting the balance between muscle protein synthesis and degradation, towards synthesis. This increases the muscle fiber cross sectional area and force generating ability, muscle quality and performance.  (https://pubmed.ncbi.nlm.nih.gov/18347672/). 

It is also essential to ensure adequate intake of vital nutrients like proteins, calcium, vitamin D, omega-3 fatty acid, zinc, magnesium, phosphorus for keeping a healthy Musculo-skeletal system. 

What type of exercises strengthens bones?

“Osteogenesis”, or formation of new bone cells known as “osteophytes” can be stimulated by dynamic loads according to studies done by Rubin and Lanyon (1984). They have defined the following principles for achieving maximal osteogenic mechanical stimulus -  

• Few load cycles are necessary and sufficient (for e.g. 4-5 jumping jacks) 
• Loads must be of high magnitude
• Loads must be applied at high rate
• Loads should produce an unusual distribution of strain

Both endurance and resisted exercises are dynamic, hence stimulates osteogenesis. It is known that aerobic exercise stimulates preferentially mitochondrial biogenesis and the synthesis of proteins involved in oxidative phosphorylation, while resistance exercise stimulates preferentially the synthesis of myofibrillar protein involved in muscle contraction. 

(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2811354/) 

How does exercise benefit respiratory system?

When we exercise and our muscles work harder, the body uses more oxygen and releases more carbon dioxide. To cope with this extra demand, our breathing has to increase from 15 breaths/minute (12 liters of air) to 40/60 breaths/minute (100 liters of air).  Circulation also speeds up to carry oxygen in response to increased demand and in order to continue exercising. In healthy lungs, there is a capacity for a large reserve which comes to aide during a bout of exertion which is deficient in unhealthy lungs. 

The respiratory muscles contract in a coordinated manner during dynamic exercises. Breathing pattern follows the principle of minimal effort and maximizing alveolar ventilation. Gas exchange across the alveolar-capillary membrane is described by Fick`s law which states that the rate of gas transfer is directly proportional to the surface area of the lungs and difference in partial pressures of the gases between alveoli and pulmonary capillaries. During exercise, there is increased blood perfusion in the lungs in response to increased peripheral oxygen demands. There is also increased respiratory muscle activity which is otherwise less in sedentary people. 

With long-term regular exercising, there is increased minute ventilation and vital capacity. Increased respiratory muscle strength has also been seen as a result of increased work of breathing during high intensity exercises which leads to better ventilation and perfusion.   

How does exercise improve mental health?

In the era of increasing stress and consequentially chronic disease, lifestyle modifications can be a cost-effective way to improve health and quality of life. Other than the well-known varied health benefits of exercises on different bodily functions, one often over-looked benefit is the impact of physical activity on mental health. These benefits in mental health are known to be triggered by exercise-induced increased blood circulation in the brain which leads to physiological changes in the hypothalamic-pituitary axis (HPA). The HPA communicates with various regions within the brain including the limbic system, which controls motivation and mood; the amygdala, which generates fear in response to stress; and the hippocampus, which plays and important part in memory formation as well as in mood and motivation. 

Depending upon the intensity of exercise, the brain releases chemical messengers called the “neurotransmitters” which relays communication throughout the various parts of the nervous system. The most common neurotransmitter released during a bout of exercise are endorphins which is responsible for blocking pain within the body, increase sensation of pleasure and relaxation. Studies have suggested that the combined effects of endorphins and endocannabinoids working in tandem produces euphoria. 

Dopamine is another neurotransmitter released after exercise which produces the feeling of pleasure. It is also responsible for other processes in the body like regulating heart rate, sleep cycle, mood, attention, motivation, memory, learning and pain processing.

Emerging research in humans have shown that physical activity can cause neuroplastic changes at synaptic level which may contribute to improved cognition and memory. These neuroplastic changes may be of significant benefit to patients with Alzheimer`s disease, ADHD, depression and anxiety all of which have shown promising results towards impact of regular exercises to mitigate neurodegenerative changes.