Chest tightness when walking outside but not at gym
Hi everybody, I live in Sierra Vista, AZ, altitude of 5300 ft. My exercise routine includes walking at fast pace 6 days a week for 35-45 mins; let's say half of that time I do it outside and half on the threadmill or the elyptical machine at the gym. The question I have is this: why is it that 90% of the time when I walk…
