A number of rhythmic processes are responsible for your body function, with the inhalation and exhalation of breathing being a prime example. Commonly overlooked because of its automatic function, breathing is an essential process that can be trained as much as any conscious function of the body. Techniques to improve the exchange of oxygen and carbon dioxide will support aerobic exercise and physical training by optimizing cell and tissue function in skeletal muscles.
Respiratory Physiology
Your pulmonary system regulates the absorption of oxygen and removal of carbon dioxide, or CO2. During exercise, the rate of carbon dioxide production and oxygen consumption increases in contracting skeletal muscle. To prevent an unhealthy change in blood gas concentration, your brain stimulates the respiratory system to increase the rate and depth of breathing. Without such adaptations, exercise would produce dramatic, unsustainable increases in blood carbon dioxide.
The 3:2 Ratio
According to military fitness trainer and former Navy SEAL Stew Smith, a good rule of thumb to ensure full muscle oxygenation and carbon dioxide removal during aerobic exercise is to use a 3:2 ratio of inhalation to exhalation. One way to internalize this rhythm is to inhale for three steps, then exhale for the next two; eventually your breathing will naturally fall into this 3:2 rhythm. Using this approach to breathing during running will help control your heart rate, increase performance and give you more energy throughout your workout.
Exhalation During Heavy Lifting
Weightlifting requires a slightly different focus on your breathing. Rather than developing a rhythmic breathing pattern, it is essential to fully exhale while exerting yourself during a lifting exercise. Inhalation should occur during relaxation. For example, when working out on bench press, exhale when you are putting up the weight and inhale as you lower it back down to your chest. This breathing pattern is vital to prevent excessive pressure buildup within your abdomen and will help prevent internal injuries such as hernias and elevations in blood pressure.
Effect on CO2
Deep, controlled breaths during exercise will improve your lungs' ability to expel carbon dioxide from your system. The business end of the lungs lies deep within the airways, with structures called alveoli acting to exchange oxygen in the air for carbon dioxide in the blood. This means that with each shallow breath, there is a significant volume of air not participating in gas exchange. By fully exhaling your breath, you are allowing the most efficient rate of gas exchange possible.
Consequences of Shallow Breathing
There are several lung conditions, including chronic obstructive pulmonary disease, or COPD, which have demonstrated the long-term effects of shallow breathing. According to 2007 research from Columbia University, a major consequence of COPD is increased blood carbon dioxide. This complication is a result of the decreased lung volumes seen in patients with COPD. Because of the "obstructive" nature of the disease, these patients are forced to take shallow breaths, reducing the efficiency of carbon dioxide removal from the blood.
