What happens to your lungs during aerobic exercise.

        After publishing a blog about the heart pertaining to aerobic fitness it is only natural to make a follow up blog about oxygen during aerobic exercise.

        Take a moment and just breath, note the rhythm of the rise and fall of the chest, the pacing of your breathing. Just how normal it all feels. If you were to time how many breaths, you take in a min it would be in the range of 12-15 (pending any health concerns). During aerobic (with oxygen) exercise this may double to triple to approximately 35-45 breaths per min. -Breaking news- you breath more times during aerobic training then normal. This is due to a concept called oxygen deficit. Onset of aerobic training the aerobic system is a little slow to respond for the increased amount of oxygen. After running you know how you are still breathing hard? That principle is called Excess postexercise Oxygen Consumption (EPOC). Remember, during a lower intensity aerobic exercise oxygen pair with Macronutrients in order to provide ATP. Carbohydrates are the preferred source of fuel during aerobic training in a metabolic process called the Krebs cycle. Fats (fat oxidization) and Protein (protein oxidation) can be used in a pinch. (Also, why you should be consuming your daily protein requirements. By sparing protein the body utilizes more carbs and fats.). Much like the Cori cycle, the Krebs cycle starts with Glycogen morphing into pyruvate; with the presence of oxygen pyruvate goes into the mitochondria. From the mitochondria the Krebs cycle starts. The end result of the Krebs cycle produces 40 ATP. Now the entire process cost 2 ATP, so your body has 38 ATP to use for exercise.      

       The amount of air your breathing is called Tidal Volume. Now, the body does not use the entire Tidal Volume. Some is lost through the nose, mouth, trachea (anywhere that gas exchange does not take place. (gas exchange meaning the process of taking oxygen in an exhaling carbon dioxide). Roughly 150ml is not used during gas exchange which is called Anatomical dead space. Physiological dead space is a term for damaged alveoli (this is often negatable in healthy adults). Once air (outside of dead spaces) comes into the lungs and cells oxygen is used. The byproduct is called Carbon Dioxide and that is expelled by the lungs into the atmosphere.

    

       Once oxygen reaches the tissues the amount of oxygen that is consumed is called the Oxygen uptake. Many factors influence the demand for oxygen: muscle mass, metabolic efficiency and intensity of exercise. larger muscle mass (think running/rowing or cross-country skiing as opposed to stationary bike) and more intensity (faster tempo runs/intervals). Increased metabolic efficiency allows for an increase in oxygen uptake (better trained-more oxygen). The maximal oxygen uptake is better known as Vo2 max. Vo2 max is generally considered the gold standard of cardiovascular fitness. A true Vo2 max is typically found in a lab. Ironically Roger Banister (first miler to run under 4 minutes) inadvertently studied and implemented this during his training. It can be calculated by hand; however, it does require some math. Vo2=Q (Cardiac Output) times a-vo2 difference. It can also be determined in field testing (not as concrete but doable). Generally testing consists of a 1.5-mile run. For example, a 25-year-old male that runs a 10-minute 1.5 mile has an approximate Vo2 max of 52.