Key structures involved in breathing

Breathing, also known as respiration, is the process of taking air into the lungs and releasing it back out. This action relies on specific muscles and structures that work together to change the volume and pressure inside the chest cavity.

Main muscles and components

• Diaphragm - A dome-shaped muscle forming a sheet at the base of the chest cavity, separating it from the abdomen.
• Intercostal muscles - Muscles located between the ribs that help to raise and lower the ribcage during breathing.
• Ribcage - A bony structure made up of ribs and the intercostal muscles between them, which encloses and protects the lungs while allowing movement to alter lung volume.

The process of inhalation

Inhalation, also called inspiration, is the act of breathing in. This process increases the space inside the chest cavity, lowering the pressure and allowing air to flow into the lungs.

Steps in inhalation

1. The intercostal muscles contract, pulling the ribcage outwards and upwards to enlarge the chest cavity.
2. At the same time, the diaphragm contracts and flattens, moving downwards and further increasing the volume of the chest cavity.
3. As the chest cavity expands, the volume of the lungs also increases, which reduces the air pressure inside them.
4. Because the pressure in the lungs is now lower than the outside air pressure, air rich in oxygen is drawn into the lungs to equalise the pressure.

The process of exhalation

Exhalation, also known as expiration, is the act of breathing out. This reverses the changes from inhalation, decreasing the chest cavity's volume and raising the pressure to expel air.

Steps in exhalation

1. The intercostal muscles relax, allowing the ribcage to move inwards and downwards, which reduces the size of the chest cavity.
2. The diaphragm relaxes and returns to its dome-shaped position, moving upwards and further decreasing the chest cavity's volume.
3. As the chest cavity shrinks, the volume of the lungs reduces, causing the air pressure inside them to increase.
4. With higher pressure in the lungs than outside, air containing carbon dioxide is forced out of the body.

How exercise improves respiratory efficiency

Regular physical activity can enhance the respiratory system by strengthening the muscles involved in breathing and increasing overall lung capacity. This improvement allows the body to take in more oxygen and remove carbon dioxide more effectively, supporting better performance during sports and exercise.

Training effects on breathing muscles

• Exercise pushes the respiratory system to its limits, training the intercostal muscles and diaphragm to become stronger and more efficient.
• During inhalation, additional muscles like the pectorals (chest muscles) and certain neck muscles can be engaged to expand the chest cavity further, while keeping the shoulders relaxed for optimal movement.
• In exhalation, the abdominal muscles (muscles of the abdomen) can contract to pull the ribs downwards, forcing out more air and emptying the lungs more completely.

Benefits of regular exercise on respiration

• Increased muscle strength - The intercostal muscles and diaphragm gain power, allowing for greater expansion of the ribcage and more significant flattening of the diaphragm.
• Larger lung volume - Stronger muscles lead to bigger changes in chest cavity size, increasing the amount of air the lungs can hold.
• Improved oxygen intake - Enhanced efficiency means more oxygen can be drawn in per breath, enabling athletes to maintain higher-intensity activities for longer periods without fatigue.