There are different types of breathing. We breathe from the nose, mouth, fast, neck, and yes, a yawn and a sigh is a type of breathing. Because of the bras that women wear they are breathing usually from the neck up.
We take about 18 breaths a minute and breathe in 12,000 quarts of air a day. We use only 1/8 of our vital capacity. Vital capacity is how much air you can inhale and exhale. This decreases with age.