Cold Weather, Deep Breathing, and Running

SoCal has been having a sprint of cold weather, with some night temperatures into the low forties and daytime highs into the high fifties. I have been running regularly, and, as posted in previous notes since early November, had difficulty drawing a deep breath, with abdominal rather than chest action, through my nostrils. This has persisted through different weather conditions and test changes in my diet, with the one constant variable being cool or cold temperatures. Today, after two days of light rain, the sun has erupted in the sky, the humidity has dropped, and temperature is in the sixties. Still, I could not draw a deep breath through my nostrils and had to run doing mouth breathing to draw deep breaths. This was adequate. I ran 14 minutes, equivalent to about 14 100-yard intervals by my old reckoning. I was not exhauasted and had stamina and leg strength all the way, over the 2.3 mile route.