Sometimes I feel like I have a head cold towards the end of a workout. My ears block up as do my sinuses at the back of my throat. I can breathe through my nose but my ears block up more and I feel and hear like I'm under water. I talk like I have a stuffy nose too. Takes about 20 minutes for the stuffiness to go away once I'm done. Usually happens with longer training sessions. My ears do block up fairly easy when changing elevation like driving up or down a hill but I can pop them just as easily. I can't pop them at all when it happens during a workout.
Anyone else experience this or have an explanation? What happens during training that would cause this?