I've only been running since about beginning of May.  I have read that the first thing to improve is your heart and that it gets pretty good in about two months.

Is the heart improvement permanent?  What I mean by that is, does this improvement actually reverse years of bad habits? Obviously going back to bad habits would then be bad for the heart but would it be like starting over with a healthy heart?

I have not seen any studies, but I would assume the worst the damage, the longer it takes for the heart to get better.  And this is just me guessing, but since the heart is a muscle, it would make sense for it to improve just like every muscle.  As to whether the improvement is permanent, I would guess it's the same as when you stop exercising or lifting weights; just like every muscle.

The best thing for your heart is to fall in love or get a kitten.  You could also celebrate Christmas, as that is said to have made the Grinch's heart grow 2 sizes.

 

Clearly I can't come to you for hard FACTS!  According to the Wiki...

And what happened then...? Well...in Who-ville they say
That the Grinch's small heart grew three sizes that day! 

 

 

I loved your response!!!

Can running reverse years of bad habits?  The short answer is "yes."  There is no question that regular aerobic exercise will strengthen your heart and that is a good thing in and of itself.  There is a good bit of evidence, although not conclusive as far as I can tell, that regular exercise may reduce the amount of plaque in your arteries.  It certainly won't eliminate it but it might reduce it enough not to be an issue until some breaks loose when you are 90.  In diabetes patients, one study found improved coronary and vascular function and markedly decreased vessel inflammation 10 weeks after beginning an exercise regime.  Exercise raises your HDL (good cholesterol) and that helps to remove the LDL plaque buildup.  (I no longer call LDL "bad cholesterol" because your body needs small quantities of it).  

Would regular exercise put you in the position of a person who had never had those bad habits?  Who knows.  I do know that the human body is amazingly resilient.  If you are a smoker for example, and you quit before age 50, with about 20 years, your risk of dying from various causes is the same as that of a lifelong non-smoker.  Thus, I would imagine that exercise can certainly reduce many of the effects of years of bad habits.

I smoked two packs of cigarettes a day from age 15 to age 45.  I started running in March, 2008 and quit smoking in July, 2008.  I can run a mile in under 6:00 so I obviously have a fairly good cardiovascular system.  Have I reversed the damage done from 30 years of smoking combined with nearly that many years overweight or obese?  I doubt it but I do think I have reversed some of it.

You could also celebrate Christmas, as that is said to have made the Grinch's heart grow 2 sizes.

LOL sugnim!   Then again, I've wondered if he had an enlarged heart due to heart failure from his years as a stingy, mean grinch.