Our 18 year-old grandson, a serious competitive swimmer, is in superb physical condition. Because he has been unusually tired lately in practice, his coach checked his heart rate after an intensive set of sprints. It was a lot higher than most of the senior swimmers. Also his recovery time took quite a lot longer than coach typically sees. Additionally, our grandson s resting heart rate was 80, which seemed high for someone of his athleticism. Because this young man had been noticeably more tired lately, our daughter took him for blood work about 3 weeks ago, and he was not anemic. His mom (our daughter) is taking him to his doctor tomorrow. Our granddaughter is a nurse at Vanderbilt Children s Hospital in cardiology, and suggested that the doctor likely will test for mononucleosis before doing an EKG or other heart tests. Does that sound about right? Thank you in advance for considering this information and replying to our concerns.