Understand the Importance of Forced Vital Capacity

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March 13, 2023

Forced vital capacity (FVC) is a crucial measurement obtained through spirometry or pulmonary function testing. It assesses lung health, airflow, and aids in diagnosing diseases and evaluating the effectiveness of medical treatments.

FVC represents the maximum amount of air a person can forcefully exhale after taking a deep breath. It holds significance for both health monitoring and enhancing physical performance.

To learn more about the importance of Forced vital capacity (FVC), its testing methods, and how breathing training can help improve it, continue reading.

What is Forced Vital Capacity?

Forced vital capacity (FVC) is a crucial measurement that evaluates lung size in liters, representing the volume of air that can be exhaled following a deep inhalation. It plays a vital role in diagnosing, monitoring, and treating lung diseases.

Spirometry, a diagnostic test, involves forcefully exhaling into a spirometer to record various lung function measurements. This test is beneficial as it can detect lung function abnormalities even in the absence of symptoms, and it helps assess the effectiveness of medical treatments, ensuring the restoration of normal airflow. Results within 80% of the reference value are considered normal, providing valuable insights into an individual’s respiratory health.

Parameters of Vital Capacity to assess 

In spirometry, three important measurements (FVC, FEV1, and FEV1/FVC ratio) of an individual are compared to reference values. These reference values are based on healthy individuals with normal lung function and provide doctors with expected values based on factors such as sex, age, and height.

Vital capacity (VC) represents the maximum volume of air that can be exhaled after a deep inhalation. It encompasses tidal volume, inspiratory reserve volume, and expiratory reserve volume.

(VC = V + IRV + ERV)

Vital capacity may be measured as inspiratory vital capacity (IVC), slow vital capacity (SVC), or forced vital capacity (FVC). The FVC is similar to VC, but it is measured as the patient exhales with maximum speed and effort.

Forced Vital Capacity (FVC)

Forced vital capacity is the total amount of air that can be exhaled following a deep inhalation in an FVC test. Thenormal FVC range for an adult is between 3liters and 5liters.

Forced expiratory volume (FEV1)

Forced expiratory volume is the amount of air forcefully exhaled in one second following a deep inhalation (FEV1).

FEV1/ FVC ratio 

This number represents the percent of the lung size (FVC) that can be exhaled in one second (FEV1).

The normal value for the FEV1/FVC ratio is 70%. Abnormalities of the FEV1 and FEV1/FVC are the result of a decrease in the airflow through the lungs, which may be caused by obstructive lung diseases.

Examples of obstructive diseases include emphysema and asthma. It is also possible to have situations where both restrictive and obstructive diseases are present.

Understanding Forced Vital Capacity and Your Lung Function 

First, it is important to point out that your body will automatically adjust to your need for oxygen. For example, when you are physically active and need greater amounts of oxygen for your muscles, your respiratory breathing rate will speed up to provide oxygen to your body and muscles faster. That happens automatically in a process where sensors in your brain, blood vessels, muscles, and lungs detect your level of oxygen and carbon dioxide. 

The amount that you exhale and breathe from your lungs, which is measured in the forced vital capacity tests, also indicates the residual volume, which is another important measurement of your lung function. Residual volume is the volume of air that remains in the lungs after maximum forceful expiration. In other words, it is the volume of air that cannot be expelled from the lungs.

The residual volume helps the lung tissues from sticking together and prevents large fluctuations of O2 and CO2. However, too much of what is left in your lungs is unhealthy, and that is why you want to limit the residual volume. 

Taking deeper breaths reduces residual volume and expands lung capacity, allowing for greater volumes of inhaled and exhaled air. This deep breathing acts as training and exercise, strengthening the entire respiratory system, including the diaphragm, intercostal muscles, and abdominals.

The different parameters of lung volume

As seen in the graph below, the volume of air that we inhale and exhale differs.

As depicted, the total lung capacity is about 5½ liters of air; however, most of this capacity is not used during normal breathing.

Tidal volume is defined as the volume of air moved into and out of the lungs during each ventilation cycle. At rest, an adult’s tidal volume is about ½ liter (or only about 10% of total lung volume).

The inspiratory reserve volume is the amount of air that can be taken into the lungs (above the tidal volume) upon forced inspiration.

The expiratory reserve volume is the amount of air that can be pushed out of the lungs (beyond the tidal volume) upon forced expiration.

Vital capacity is the total volume of air that can be moved into and out of the lungs.

Besides the factors that set a natural limit to our lungs, we are able to train and extend these different volumes and capacities. As much of the breathing process happens automatically, you train to optimize your lung function and breathing pattern.

The figure shows the lung volumes and capacities of normal adults.

forced vital capacity measuring lung capacity

Improve performance with deep breathing training

Deep breathing can benefit individuals with chronic lung diseases by training their breathing and improving overall physical performance.

During intense physical activity, panting occurs as the body seeks more oxygen, impacting endurance. However, by practicing deep breathing, individuals automatically enhance their oxygen intake per breath and strengthen their respiratory muscles, particularly the diaphragm. This utilization of greater lung capacity increases vital capacity, leading to improved oxygen delivery to muscles.

Consequently, individuals can train for longer periods with reduced exertion. Airofit breathing trainer offers daily exercises to enhance vital capacity, proactively strengthening breathing muscles for deeper breaths during high-intensity activities. Deeper breathing requires slightly more energy but allows increased oxygen absorption into the bloodstream, enhancing performance and energy preservation.