Avid Runner Suddenly Losing Endurance?
My son is a HS junior, very dedicated cross country (his favorite season) and also runs mile/2-mile during the track season. He's very well-coached, understands a running regiment, when to push, when to run light, and when to rest... just for background.
He ran a 17:20 PR in his final 5k last fall and a 4:46 mile at the end of his sophomore year, he trains diligently and has been consistently improving every season though not breakingrecords just yet. Suddenly, he's regressing... he's getting tired faster, claims he can't breathe and his times have dropped off considerably throughout the summer. His training hasn't changed, sleep habits normal, nutrition normal, hydrates properly... stretches, recovers properly, etc... my wife and I took him for blood work because we don't know how to help. No deficiency, all normal.
I have no idea what to tell him nor how to help him. His times are slower, he's losing his confidence and is super frustrated. Why would a healthy, strong 16yr old suddenly slow down so much and lose his lungs? Please help, thank you.