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.
There is one thing that everyone who lives and visits Maricopa County has in common. We all breathe air. The average adult takes about 15 breaths per minute, inhaling nearly two gallons of air. With 21,600 breaths per day that equals 2,880 gallons of air each day. Maricopa County Air Quality Department is asking everyone to help keep our air clean and our residents healthy.