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.
The alveoli in your lungs are covered with tiny blood vessels called capillaries. It's there in your alveoli that the oxygen in the air you breathe passes into your blood via the capillaries. From your capillaries, the oxygenated blood travels to the heart, where it's pumped out to the rest of the cells in your body. The air you breathe every day is important to your health, but did you realize that air pollution can make breathing more difficult and even cause all sorts of health problems? 2  Jump online to check out the Clean Air Detective Follow the instructions to do a basic investigation of the air you breathe every day.