Lung capacity is the total amount of air your lungs can hold and move during breathing. It indicates how efficiently your respiratory system functions, impacting overall health by showing how well your body takes in oxygen and expels carbon dioxide.
What Does Lung Capacity Mean?
Lung capacity is measured using spirometry, a test that assesses lung volumes and airflow. Common measurements include Forced Vital Capacity (FVC), the total air exhaled after a maximal inhalation, and Forced Expiratory Volume in 1 second (FEV1), the air exhaled in the first second of that breath. These values are compared to predicted norms based on age, height, sex, and ethnicity. For healthy adults aged 20-60, normal FVC and FEV1 percentages are typically above 80%.
Interpreting 70% Lung Capacity
A lung capacity measurement of 70% of the predicted value is lower than the normal range, which is typically 80% to 120%. Specifically, FEV1 or FVC between 70-79% of predicted values is classified as a mild reduction in lung function. While this indicates a deviation, its significance depends on individual symptoms and health history. A 70% lung capacity result warrants further medical evaluation to understand the underlying reasons. For example, an FEV1 to FVC ratio below 70% often indicates an obstructive lung disease. In restrictive lung diseases, both FEV1 and FVC may be reduced, but their ratio might remain normal or even increase.
Common Causes of Reduced Lung Capacity
Reduced lung capacity can stem from various conditions, broadly categorized into obstructive and restrictive lung diseases. Obstructive lung diseases, such as chronic obstructive pulmonary disease (COPD), asthma, bronchiectasis, and cystic fibrosis, make it difficult to exhale air due to narrowed airways. This narrowing can be caused by inflammation, mucus buildup, or airway damage.
Restrictive lung diseases prevent the lungs from fully expanding during inhalation, leading to a decrease in the total air they can hold. Examples include interstitial lung diseases like pulmonary fibrosis and sarcoidosis, and conditions affecting the chest wall or muscles, such as severe obesity, scoliosis, or neuromuscular diseases like muscular dystrophy. Age also plays a role, as lung function naturally declines after around age 35 due to weakening diaphragm muscles, shrinking rib cage bones, and loss of lung tissue elasticity.
What to Do if You Have Reduced Lung Capacity
If you receive a spirometry result indicating 70% lung capacity, seeking a comprehensive medical evaluation is the next step. A healthcare professional can perform additional diagnostic tests, such as further pulmonary function tests or imaging, to determine the specific cause.
Management strategies may involve medication for underlying conditions like asthma or COPD, or pulmonary rehabilitation. This supervised program improves lung function and breathing efficiency, often including exercises like diaphragmatic and pursed-lip breathing to strengthen respiratory muscles. Lifestyle adjustments, such as quitting smoking, regular physical activity, a healthy diet, and avoiding pollutants, also support lung health and may improve capacity over time.