Whether partaking in weight lifting or cardiovascular exercise, every exercise requires the use of a muscle group. Everyone experiences the same bodily functions during exercise, heavy breathing, sweating and an increase in heart rate. These are all natural reactions to exercise no matter how fit you are. When we exercise a huge demand is put on the body to provide the working muscles with large amounts of oxygen in order to help us keep going.
Up to a certain threshold the body can provide sufficient oxygen to meet the needs of the exercise, but when muscle exertion increases there comes a point where the supply of oxygen is too slow and cannot provide muscle fibers with oxygen quick enough. During exercise the body has to work hard to pump oxygen to the muscles being used. Blood flow is increased and the blood vessels in the muscles dilate to allow oxygen to get through to the muscles at a faster rate.
But it isn’t just oxygen that is required in this process; in fact that is just the beginning. Think of your muscles as biochemical motors, they need energy to perform, otherwise they would simply shutdown. The required energy source is called adenosine triphosphate (ATP). ATP is burnt up as a fuel, and to burn this fuel the muscles must do three things:
- Take on enough oxygen – To produce the ATP.
- Expel metabolic waste – Carbon dioxide and lactic acid.
- Expel heat – muscles produce more heat the harder they work.
As exercise increases so does the pressure on the heart as it works faster to supply oxygen which is carried to the muscles by the blood. For this reason it is particularly dangerous for anyone with a known heart condition to partake in endurance related exercise.
The harder you train the more ATP your muscles need, thus the importance of learning to breathe properly when exercising. Without sufficient oxygen lactic acid builds up at a faster rate, causing that burning sensation you feel when you push yourself that little bit further. Once you slow down or stop lifting weights, lactic acid is quickly diffused and around 80% of the lactic acid build up is converted in the liver back to glucose or glycogen.
The body does a number of impressive things to support the muscles as they work harder. An important part of the oxygenation process is blood diversion. Blood that is normally supplied to the kidneys and the stomach is sent to the muscles instead, in fact; during exercise your stomach shuts down in order to allow more blood (oxygen) through to the muscles at work. Another key function is sweating. Your body keeps you cool by sweating out the heat from the working muscles. At the same time your lungs and respiratory system make you breathe harder to take on more oxygen.
The most important functionality of this entire process is how your body gets the oxygen out of the blood. It does this through an exchange of oxygen and carbon dioxide using a protein called hemoglobin. Hemoglobin is found in red blood cells and has the ability to bind oxygen or carbon dioxide. The normal state of muscle is one of high carbon dioxide concentration and low oxygen concentration, so during exercise hemoglobin is instructed to release more oxygen than normal to supplement the additional requirement for oxygen. Hemoglobin is transported via the heart and blood vessels to the muscles at work, releasing oxygen and binding carbon dioxide for expulsion.