Keep your leg at a 90-degree angle and your knee and foot at the same height. Avoid rotating your spine at any point during the exercise. Pause at the top for two seconds before lowering your knee to the floor. Repeat 15-25 times before performing the exercises with the other leg.
Inhaled air is about 20-percent oxygen. Exhaled air is about 15-percent oxygen. Therefore, about 5-percent of breathed air is consumed in each breath. That air is converted to carbon dioxide. So, as far as how much air is actually used, human beings take in about 550 liters of pure oxygen per day. A person who is exercising uses a lot more oxygen than that.
It processes the air that you breathe before it enters your lungs. Most of this activity takes place in and on the turbinates, located on the sides of the nasal passages. In an adult, 18,000 to 20,000 liters of air pass through the nose each day. Filtering all that air and retaining particles as small as a pollen grain with 100% efficiency. 2  Humidifiing the air that you breathe, adding moisture to the air to prevent dryness of the lining of the lungs and bronchial tubes.