Some factors affecting vital capacity are pregnancy, sex, age, physical fitness, muscle mass, elevation and disease, according to Boundless. Some factors like pregnancy and disease can decrease vital capacity, and others like physical fitness and muscle mass can increase it.
Vital capacity or total lung capacity can be affected by several physiological and environmental factors, according to Boundless. Pregnancy, for example, can decrease vital capacity in women. During pregnancy the diaphragm is compressed by the uterus, which decreases total lung capacity.
Other physiological factors including pulmonary diseases can decrease vital capacity as well. Asthma constricts the airways allowing less air into the lungs. Therefore the lungs do not stretch as much, and their capacity decreases. Some physiological factors, such as body mass, muscle mass and physical fitness, can increase vital capacity. Some factors are genetic; for example, men have higher vital capacity than women, and people with larger body mass have higher vital capacity than those with less body mass, states Boundless.
People can increase their vital capacity by increasing their physical fitness level. Environmental factors that can affect vital capacity include elevation, suggests Boundless. People residing at higher elevations must breathe deeper because the air contains less oxygen. After an extended period of time, this can increase lung capacity.