I am a healthy 32-year old male, work out regularly in the gym, and run for about 40 min. to 1 hour once a week. Twice in the last few months I experienced fever few hours after running
. It felt like a beginning of the flu (muscle aches, fever, lack of energy), but with no cough, sore throat, etc. Fever lasts for about a day, and I feel lack of energy for one more day, but after 48 hours from the start of this condition I feel absolutely healthy.