My NT son has had problems with that but he was also born with non life threatening heart problem. He has a heart murmur too. It does not limit anything he does we just have to monitor him closely. My son was even cleared to play football last year. He tires easily but is very active. He runs 1 mile races and participates in PE at school. But like I said we have to monitor him closely and when he says he's tired it is an automatic stop to rest.

Yes thanks @A MyAutismTeam Member. I took him to a cardiologist and he had a normal EKG and echo. We are signed up to have a heart monitor for a weekend. But his level has appeared normal. We thought maybe his heart is fast sometimes but not other times. He takes Strattera. Could contribute to it. But the cardiologist didn't see anything that concerned him

Thanks @A MyAutismTeam Member!
I'm glad to hear that it's not a big impact physically. My son is not into team sports anyway. But he enjoys doing gymnastics, swimming, running.
But he does tire easily & become cold easily. Sometimes I wonder if behaviors I had attributed to sensory issues were related to the heart. He stops and lies down on the ground a lot.

Thank you @A MyAutismTeam Member! In past medical appointment people had commented previously that his heart beat was fast but no one has ever said that it should be checked out until now. What does it mean for your son? Does it change anything?