Processing Oxygen

Structure of human hemoglobin. The proteins' α and β subunits are in red and blue, and the iron-containing heme groups in green. From PDB 1GZX Proteopedia Hemoglobin
 

    Our marvelous brains operate at an internal warp speed, demanding varied foods for maintenance, neuron growth, creative endeavors and focus.  Our bodies send the brain blood oxygen in copious amounts to burn all that food and keep us awake - and even when we sleep our brains use plenty of energy. 

    A good cardiovascular system supplies the brain with well-oxygenated blood.  That blood should be be of the highest quality.  Pilots have special oxygen needs.

    Flying aircraft exposes us to a unique set of physical conditions: we are forced into a sitting position with a limited range of motion; we are tasked with maintaining a high degree of attentiveness to ensure our safety and the safety of others; we are expected to perform mentally at a high level for hours at a time; and we do all this at high pressure altitudes.  Being fit to perform is an obvious need for each pilot.   

    The FARs include recognition that exposure to high pressure altitude degrades pilot performance.  We are required to use breathing oxygen above 12,500 feet MSL after 30 minutes, and so on.  If we fly at night, we are strongly encouraged to use oxygen while flying higher than 5,000 feet for more than a short period.  

    People who know me know that I run for conditioning and pleasure.  I began running in 1975, just before moving to Chattanooga, and have continued to stay in shape by running ever since that year.  I've taken mild abuse from friends and acquaintances over running, but most people I know accept my habit with either admiration or neutrality.  In 37 years of running, I’ve learned a few things about how bodies react to conditioning which are worth sharing.  For instance, I learned how to reduce hay fever symptoms to a level that has kept me from needing any kind of drug for the past 35 years.  It’s simple sounding, but works. 

    I grew up in Lafayette, Indiana, where the early fall pollen count was so high that I would lapse into a sniveling and sneezing condition for the month of  September.  Chlorpheniramine gave some relief, and my mother encouraged me  to bear up under the assault of the evil pollens.  When the pollen count went down, I was back to normal.  We moved to Florida when I was 12, and those pollens weren’t there, so I lived for 10 years without a hay fever attack, except for a summertime visit to Lafayette, Indiana, which I remember mostly for the amazing sneezing and sniveling attack I had while sitting in a laundromat washing my clothes.  Leaving Florida, I lived in Virginia and DC with only minor problems, and then returned to the midwest to go to school in Louisville.  There were some fall symptoms there.  Then I moved to Chattanooga.  I snuffled a little during the first fall, and had springtime hay fever there, also.  I was now running regularly, and enjoying being fit.  I noticed that after a run my sinuses were clear and would stay clear for a while during the “season”.  Then I encountered Science of Breath, by Yogi Ramacharaka.  It’s a yogi breathing manual promoting deep nose breathing as an important wellness function. 

    Oxygen is carried from the permeable membranes of the lungs to the tissues by binding with hemoglobin in a wonderful dance of chemical magic.  Down at the capillary level, these cells can squeeze themselves to fit through a narrow passage, or secrete ATP to cause the capillary to expand so that the red cells can pass through to oxygenate the tissue.  Our red blood cells are constantly being replaced by our bone marrow (over 2 million new ones every second), and live for 100 to 120 days before being recycled in the body.  When we train our bodies aerobically, it places demands for more oxygen-carrying capacity on the body.  The body responds by producing more red blood cells, increasing lung capacity, making more capillaries in the skeletal muscles, enlarging coronary arteries, making more resilient vascular walls, increasing blood flow to the brain and many other benefits which can be summed up as “the training effect”.

    Combining running and yoga breathing, I discovered that 5 miles with good breathing would relieve hay fever for a whole day.  Working at it for a while conditioned my body to not respond to the allergens, and today I just don’t have the symptoms, although my running averages much less than 5 miles per day (it’s somewhere in the 2 to 3 mile range - I also don’t keep track of it any more.)

    Running (with good breathing) keeps me off a drug which the FAA doesn’t like.  (FAA medical rules allow only a very few antihistamines to be used by pilots, and those only after a trial period by the pilot using them.  My old childhood friend Chlorpheniramine is not on the approved list.  It’s obvious why the FAA doesn’t like hay fever - a sinus block or clogged eustachian tube could cause a crash  - and it’s obvious why they don’t like drugs that make you sleepy. )

    The deep “yogi” breathing also promotes being awake, so there’s certainly a flying benefit to breathing well. 

    Pilots can also degrade their lungs and blood by various means.      Deconditioning is the most common way - we just don’t do anything.  Piloting an airplane is sedentary.  There is practically no muscle used in the activity.  A passively fit person is OK until a big stress comes along, and then his/her body may be unprepared to handle the emergency.  The fit pilot is more awake, with a higher blood oxygen level in the brain, and better able to take stresses.

    Smoking degrades all performance: carbon monoxide binds 200 times more easily to red cells than oxygen, and once bound, stays bound until that red cell is recycled.  Oxygen binds to the red cells lightly, so that it can un-bind at the tissue level to provide oxygen to the tissue.  Any exposure to CO reduces your body’s ability to transmit oxygen to the tissues, and the effect lasts for up to four months after every exposure.  This effect is immediate and long-lasting; why any thinking pilot would smoke is a mystery to me.  This is notwithstanding the known other “benefits” of tobacco use such as heart and lung disease, cancer, premature skin aging, bone density loss, the health risks of second hand smoke on others, and going around smelling of tobacco smoke.  Very few smokers work out, so they also miss all of the beneficial effects of training. 

    Alcohol consumption counters many of the effects of training in the body.  Some negatives include: reduced metabolism and endurance, inhibiting uptake of essential nutrients like B vitamins, replacing consumption of beneficial complex carbohydrates with simple sugars, and making us stupid. 

    Ask yourself, “would I prefer to fly with a pilot who is an aerobically fit, non-smoker, who doesn’t use alcohol or even prescription drugs, or a person with one or more risk factors for abuse of his/her own body?”  If your answer is to seek the fit pilot, then reflect on it, and throw away the bad habits and replace them with positive actions.  You’ll like the benefits, your AME will like you better, and your passengers will fly in a safer environment even if they don’t know any of those details.

    For another take on “processing oxygen” see the story about the Chickamauga Chase 2013.