Are marathons good or bad for your heart?
A new study found marathon training can help cut the risk of cardiovascular disease among middle-aged men.
Researchers looked at dozens of runners participating in an 18-week marathon training program that included group runs and endurance training.
After completing the program, the men showed improvements in the size, shape and overall function of the heart.
They also had lower cholesterol levels and their body mass index dropped one-percent.
This study was led by researchers at Massachusetts General Hospital and presented at the American College of Cardiology's Annual Scientific Session