Hello There. I can understand your concern and firstly would like to wish you all the very best for the upcoming marathon. at high altitudes, the higher you go, the oxygen concentration falls and that can cause some risks as while you would be running, you would need a continuous supply of oxygen. kindly consult a pulmonologist and get yourself checked out by him so that you know you are fit lung wise. he only will suggest you what tests you need to get done. pulmonary function test is one basic test that will be required. practice, meditation, yoga and pranayama they do help a lot. best regards, Dr. Anil kumar jain

Hello .. In high altitude oxygen concentration decreases and person will become hypoxic... Soldiers themselves find it difficult to adjust to high altitude ... You should be there at high altitude for few months to get acclimatise to that environment , also you should consider cold climate ... Get pulmonary function test for now..