What is exercise physiology | Fitness tips

 Concept of physical fitness

Physical fitness is to the human body what fine-tuning is to an engine:which is optimal functioning of all physiologic systems of  the body, particularly the cardiovascular , pulmonary, and musculoskeletal systems. it enables us to perform to our potential. Fitness can be described as a condition that helps us look,feel and do our best . More specifically, it is: "The ability to perform daily tasks vigorously and alertly, with energy left over for enjoying leisure-time activities and meeting emergency demands.

We strive toward an optimal state of well being since what we do with our bodies also affected what we can do with our minds, fitness influences to some degree qualities such as mental alertness, emotional stability and helps us to deal better with stress of daily life. As we undertake a fitness program, its important to remember that fitness is an individual quality that varies from person to person. It is influenced by age, sex, heredity, personal habits, exercise and eating practices.

The first three factors are not in  our hands, however it is within our power to change and improve the other factors. As our lifestyles change , so does out level of health. Exercise provides stimulus that creates significant physiological changes (both acute chronic)in the human body. An in-depth knowledge and understanding of the cardiovascular, respiratory , muscular and neurological systems and their role during exercise is vital for fitness professionals.

Primary components	Description
Cardiorespiratory Endurance	Ability of the circulatory and respiratory systems to deliver oxygen and nutrients to the working muscles, for a sustained period  of the time without fatiguing.
Muscular strength	Ability of a muscle to expert maximum force against a load/resistance during a single contraction.
Muscular Endurance	Ability of a muscle or a group of muscles, to sustain repeated contractions or to continue applying force to extended  length of time without fatiguing. Improved muscle endurance especially of the torso stabilizers or core muscles has shown a strong correlation between muscle imbalances resulting in lower back pain.
Flexibility	Pain free range of motion that can be accomplished at the joint (articulation).
Body composition	Relative  amount of  fat - free-mass (muscle, bone, vital tissue and organs) to fat mass (Adipose tissue).

 

Secondary components	Description
Agility	Ability to rapidly and accurately change position of body in space.
Balance	Ability to maintain specific body positions in either a stationary or dynamic (moving) situation.
Coordination	Ability to use all body parts together to produce smooth and fluid motion.
Power	Is the product of strength and speed . Power is also known as explosive strength.
Reaction time	The time required responding to a specific stimulus.
Speed	Ability to perform a movement within a short period of time.

 

Cardiovascular System

The Cardiovascular system works in conjunction with the respiratory system to deliver oxygen to the tissues of the body and remove carbon dioxide. It is responsible for maintaining homeostasis in the body. Even at the rest on an average 5 liters of blood is pumped by the heart per minute (Cardiac output) . One of the biggest challenges to homeostasis is exercise. A heavy exercise session can increase demand for oxygen by up to 15 to 25 times above the resting level. In order to this effectively 

the cardiovascular system is divided into two circuits: Pulmonary and Systemic circuit. The pulmonary circuit is made up of the heart , lungs, pulmonary veins and pulmonary arteries. This circuit pumps deoxygenated blood from the hearts to the lungs where it becomes oxygenated and return to the heart.

The systemic circuit is made up of the heart and all the remaining arteries, arterioles, capillaries, venules and veins in the body. This circuit pumps oxygenated blood from the heart to all the tissues, muscles and organs in the body to provide them with nutrients and gases they need in order to function.

The cardiovascular system is responsible for the following functions with in the human body:

• To transport nutrients (carbohydrates, proteins and fats), gases (CO 2  and O 2 ) and waste products (lactic acid ) around the body.
• To protect the body from injection and blood loss.
• To help the body to maintain a constant body temperature (thermoregulation).
• To help maintain fluid (electrolyte) balance within the body to prevent dehydration.
• To transport hormones and enzymes to regulate physiological functions.
• To regulate the blood PH balance to control acidosis and alkalosis.

THE HEART 

The heart is a hollow, cone-shaped muscle located between the lungs and behind the sternum (breastbone). It is roughly the size of your first two-thirds of the heart is located to the left of the midline of the body and 1/3 is to the right. The heart is contained in a fluid filled protective sac called the pericardium; it prevents the beating heart from brushing against the chest. The heart has three specialized layers. The smooth, inside lining of the heart is called the endocardium. The middle layer of heart muscle is called the myocardium; it performs the primary work of the heart. The myocardium is a thicker and stronger in the left ventricle as it is responsible for pumping blood to the rest of the tissues in the body.

A thin lining called the epicardium  forms the outer most layer of the heart. the coronary arteries are the main source of the nourishment for the myocardium gets its blood supply through the chambers of the heart.

The chamber of the heart

• The heart is made up of four chambers. The chambers on the right side of the heart are the right atrium and right ventricle.
• The right atrium receives deoxygenated  blood from the body via the superior and inferior vena cava.
• The blood then flows from the right atrium the right ventricle through the tricuspid valve where it is then pumped, via the pulmonary circuit, through the pulmonary artery to the lungs for gaseous exchange (CO 2  out , O2 in ).
• Pulmonary artery is the only artery that carries de-oxygenated blood , rest of the arteries in the body carry oxygenated blood.
• The chambers on the left side of the heart are the atrium and the left ventricle.
• The left atrium receives oxygenated blood form the lungs via the pulmonary veins.
• Pulmonary vein is the only vein that carries oxygenated blood all the other vein carry de-oxygenated blood.
• The blood then flows to the left atrium to the left ventricle through the bicuspid/ mitral valve where it is then pumped, via the systemic circuit, through the aorta and then pumped out to the organs and tissues of the body.

BLOOD FLOW

• all blood enters the right side of the heart through two veins: The superior vena cava and the inferior vena cava  .
• The superior vena cava collects blood from the upper half of the body . The inferior vena cava collects blood from the lower half the body .
• Blood now enters the right atrium(RA).
• When  the RA contracts,the blood goes through the tricuspid valve  and into the right ventricle(RV). When the RV contracts, blood  is pumped through the pulmonary valve, into the pulmonary artery and into the lungs when it picks up oxygen .
• Oxygenated blood now returns to the heart from the lungs by way of the Pulmonary veins and goes into the left atrium (LA).
• When the left atrium contracts, blood travels through the mitral/bicuspid valve and into the left ventricle (LV).
• The left ventricle is the very important chamber that pumps blood through the aortic valve into the aorta.
• The aorta is the main artery of the body. It receives all the blood that the heart has pumped and distributes it to the rest of the body .
• The left ventricle has a thicker muscle that any other heart chamber because it pumps blood to the rest of the body.

Valves of the heart

There are four valves within the heart that serve to prevent the back flow of blood as it passes through the various chambers of the heart and out through the associated arteries.

1. The tricuspid valve is positioned between the right atrium and ventricle.
2. The mital valve is between the left atrium and ventricle. Collectively they are know as the "atrioventricular" valve.
3. The pulmonic valve is positioned between the right ventricle and the pulmonary artery.
4. The aortic valve is situated between the ventricle and aorta. Collectively they are known as the "semilunar" valve.

Cardiac cycle

One heart-beat consists of one contraction phase and one relaxation phase. The contraction phase, known as 'systole', occurs when the heart is relaxing and filling with blood. The sympathetic and Parasympathetic branches of the autonomic nervous system control heart contractions. The sympathetic system stimulates the heart to beat  faster while the parasympathetic system returns the heart rate to its normal resting level.

BLOOD AND BLOOD VESSELS

Blood is made up of two parts; a solid portion consisting  of red blood cells, white blood cells and platelets, and a liquid portion consisting of plasma (is approximately 90% water) . The human body generally maintains 4-5 liters of the blood in total circulation. The blood vessels make up the body's internal 'road' network linking the heart to all the organs and tissues of the body that the blood needs to reach. The five types of blood vessels in the body are:

Arteries

Arteries carry blood away from the heart at high pressure. Because of the high pressure exerted on arteries they have thick walls covered by a tough outer layer. Arteries also have  layers of elastic fibers that control the diameter of the artery.

Arterioles

Arteries divided into arterioles, which are of similar structure, however the walls are not as thick as in arteries as the pressure within the vessels has lessened by the time blood reaches them. The arterioles then divide further into capillaries.

Capillaries

Capillaries are the smallest blood vessels in the body, which allows diffusion between the blood and cells to occur. Nutrients and oxygen from the blood diffuses through the capillary walls into the tissues that need it. At the same time carbon dioxide and other waste products re-enter the capillary in the order to be processed and removed from the body.

Veins

Veins have a think outer  layer made of collagen and inner layers made of smooth muscles and elastic tissue. Veins are not further from the pumping action of the heart than arteries and as a result have much thinner walls because they operate under less pressure. As there is less pressure in the veins and no 'pump' to force blood back to the heart, veins have some special features to assist venous return ( the return of blood to the heart from the veins). The skeletal muscles surrounding veins expand and contract which presses on veins causing a pump effect. Valves are located at regular intervals in large veins.These valves ensure that blood only flows in one direction towards the heart, and they automatically close to prevent backflow of blood, similar to the valves in the heart.