Physical Health : Exercise

Physical health is the general condition of your body. It covers various things including; the absence of disease or injury, fitness level, nutrition and diet, sleep, and substance use. 

Regular exercise, a balanced diet, and sufficient rest are essential for building strong bones and muscles, boosting energy levels, and reducing the risk of chronic diseases like heart disease, stroke, and diabetes.  To usderstand how exercise improves physical health, an understanding of the Respiratory and Musculo-skeletal body systems are needed. 

The Respiratory System

The diagram below shows the main features of the respiratory system:-

Trachea - Also known as the windpipe, this muscular tube ringed with cartilage connects the nose and mouth to the lungs.

Bronchi - Each person has two bronchus which connect each lung to the trachea.

Bronchioles - Smaller than the bronchi, the bronchioles branch out smaller and smaller spreading out through the lungs. They connect the bronchi to the alveoli.

Alveoli - Also known as air sacs, the alveoli are the site of gas exchange with the blood.

Diaphragm - A large dome shaped muscle below the lungs. When a person breathes in, the diaphragm flattens, increasing the volume of the lungs, causing air to be drawn into them.

Alveoli and Gas Exchange

As stated above, it is within the alveoli that gas exchange with the blood occurs.

The alveoli are very small air-filled sacs that form the final part of the Respiratory system. The alveoli have several adaptations that allow gas exchange to happen easily:-

The alveoli have a folded structure, to give them a large surface area for gas exchange to occur over.

The walls of the alveoli are only 1 cell thick, so the gas only has to diffuse a short distance.

The alveoli are surrounded by capillaries, ensuring a good blood supply.

Gas Exchange

The function of the Respiratory system is to exchange gases with the blood. Gases will always move from regions of high concentration to low concentration by diffusion.

The diagram below shows how the two gases involved in Respiration (Oxygen and Carbon Dioxide) are exchanged within the alveoli:-

Oxygen - The concentration of Oxygen is greater in the alveoli, and so Oxygen diffuses from the alveoli into the blood.

Carbon Dioxide - The concentration of Carbon Dioxide is greater in the blood, and so the Carbon Dioxide diffuses from the blood into the alveoli.

Peak Flow and Vital Capacity

The amount of gas exchange that can occur depends on how much air can be taken in with each breath, as well as how often a person breathes.

This is why during exercise both the volume of air inhaled and the rate of breathing increase to cope with the demand for Oxygen.

There are two measurements that can be taken to measure the effect of exercise on breathing:-

1. Peak Flow - The maximum speed of air that a person can force out of their Lungs.

2. Vital Capacity - The maximum volume of air that a person can breathe out in one breath.

The diagram below shows a Peak Flow meter, a device used to measure Peak Flow:-

In the peak flow meter, the higher the speed of air being blown through the mouthpiece, the further up the scale the pointer is moved.

The image below shows a Vital Capacity test kit. The kit consists of a long plastic bag with a mouthpiece. By breathing out into the bag, the volume of air exhaled (the vital capacity) can be found:-

Case Study - Asthma

Asthma is a very common lung disease that normally starts during childhood. People with asthma will lead generally normal lives, but at certain times will suffer asthma attacks.

The diagram below shows the changes which occur during an asthma attack:-

During an asthma attack, a person's bronchioles become inflamed and swell up. This reduces the size of the airway, which can become blocked with mucus, causing the person to struggle to breathe. In severe cases, this can be fatal.

Asthma is incurable, but asthma attacks can be treated by the use of an inhaler containing medication that causes the muscles in the bronchioles to relax, opening up the airway.

Breathing and Exercise

During exercise, the cells of the body require large amounts of oxygen to release the energy they need. This means that during exercise, breathing rate increases. 

Once exercise stops, the breathing rate remains higher than normal for a short period of time. The length of this time depends on fitness level, the fitter the individual, the quicker the breating rate returns to normal. This is due to a build up of Lactic acid in the muscles during exercise.

When exercise is vigorous and/or prolonged, the lungs eventually cannot supply enough oxygen to the muscles. This changes how the muscles respire, creating Lactic Acid as a waste product which causes a 'burning' sensation in the muscles.  

The extra oxygen taken in by the increased breating rate after exercise is used to clear this Lactic acid from the muscles. 

The Circulatory System

The oxygen required for muscles to fuction needs to be transported from the lungs to the muscles, and it is the role of the circulatory system to do this. 

The diagram below shows the main features of the circulatory system:-

Heart - Main organ of the circulatory system, contracts to pump blood around the body.

Arteries - Large blood vessels which carry blood away from the heart.

Veins - Large blood vessels which carry blood to the heart.

Capillaries (Too small to be seen on diagram) - Very small blood vessels (too small to be seen above) which are present in all body tissue, oxygen and carbon dioxide transfer takes place between the capillaries and the cells of the body.

The Heart and Blood Vessels

The heart is the main organ within the circulatory system. The heart is a very strong muscle that contracts on a regular basis to pump blood around the body.

The diagram below shows the main parts of the heart:-

The heart is the main organ of the circulatory system, consisting of four chambers, which contract in sequence to pump the blood around the body.

The right side of the heart pumps deoxygenated blood to the lungs.

The left side of the heart pumps oxygenated blood to the rest of the body.

There are three main blood vessels within the body, each perform a different job and are specialised in different ways:-

The table below shows a summary of the three different blood vessels:-

Pulse Rate

The heart pumps blood around the body with such a large force that it can be felt in the blood vessels as a pulse.

A Doctor can listen to your heart (and lungs) using a Stethoscope. A stethoscope is a device that amplifies sounds to allow the doctor to hear them clearly.

The diagram below shows the main parts of a stethoscope:-

The stethoscope works by sound being received at either the drum or the diaphragm. This causes the air within the thin tubing to vibrate, carrying the sound to the earbuds.

In order to hear different sounds within the body, either the diaphragm or the bell can be used:-

Closed diaphragm - High frequency lung sounds.

Open Bell - Low frequency heart sounds.

Note - An easy way to remember which way round to use the stethoscope is open bell - open heart surgery...

Resting Pulse Rate

A person's resting pulse rate will depend on fitness level, with a fit person having a lower resting pulse rate than an unfit person. 

The healthly resting pulse rate for a human is between 60-80 beats per minute (B.P.M.). 

Different animals have different resting heart rates, usually getting higher the smaller the animal is : 

The Heart and Exercise

When you exercise, your muscles need more oxygen and nutrients than they would normally use. In order to keep up with this demand, your heart will beat faster and with greater force.

After exercise, your body has to remove the waste substances from your muscles, and so your pulse rate will take some time to return to normal.

The peak pulse rate, and the recovery time depend upon your fitness level:-