Why Respiration Increases During Exercise

Respiration---the exchange of gases that takes place when you breathe---increases during exercise because your working muscles need more oxygen. You inhale air, and the oxygen in that air enters your lungs and affixes itself to red blood cells, which are carried to the muscles. As the demand for oxygen increases, the pace of your breathing increases. After you've delivered oxygen to the blood in your lungs, you exhale carbon monoxide, which is a waste product released by working muscles.

Breathing Rates

A key measurement of an athlete's abilities, according to exercise science researchers at the University of New Mexico, is a measurement called maximum oxygen uptake, or VO2 max. This is a measure of the maximum amount of oxygen your body can deliver to working muscles while exercising as hard as you can. Your genetic make-up largely determines your VO2 max, but you can improve it through exercise.

Effect of VO2 Max

Maximum oxygen uptake explains why some athletes can go faster or exercise longer than other athletes who may have trained as much or as hard. People with a high VO2 max simply have a greater ability to deliver oxygen to working muscles. VO2 max is typically measured in a lab where the subject rides a bike or runs on a treadmill at a progressively increasing difficulty level. Many universities have the right equipment and will test you for a fee.

Starting Out

People starting to exercise after a sedentary period find that they get out of breath quickly when they exercise even at moderate levels. That's because their bodies aren't fit enough to deliver sufficient oxygen to their working muscles. But regular exercise will change that---according to Washington University researchers, your VO2 max will increase, your blood will develop new red blood cells, your heart will get stronger and your muscles will get better at utilizing all that additional oxygen.

Lactic Acid

Fit and untrained people alike can reach an exercise level where there is not enough oxygen in the blood to sufficiently supply a working muscle. When that happens---and it happens faster for unfit people than for people who regularly exercise---the muscle switches to producing energy without oxygen, Washington University researchers say. This process produces lactic acid, which makes your muscles sting and quickly forces you to stop exercising.

Measure Your Effort

Experts at Columbia University advise those just starting an exercise regimen do less-strenuous exercise until their heart, lungs and circulatory system get stronger. You can use the rate of your respiration as a way to know if you are exercising hard enough. If you are sweating but can still carry on a conversation, you are exercising at what's called a moderate intensity, and that's good enough to start gaining fitness. If you're breathing too hard to talk, you need to back off.