The more I study, the more do I realise that I have to put effort into cardiac training. Although gym/lifting weights is great and gives you numerous health benefits, it may have negative effects on the heart. Of course the negative applies more to extreme cases, with a lot of lifting and very heavy weights, but with the emerging gym & fitness trend I think this is something to think about. You get a big, strong body with a relatively weak heart. It's not trained to the same extent. In the long run, lifting heavy weights contributes to pressure overload of the heart muscle which can succesively lead to an enlarged, dilated heart and ultimately cardiac failure.
"Cardio" on the other hand, strengthens the heart muscle and promotes extensive blood vessel formation to compensate for the new, larger heart size. There's no simpler "medicine" to keep the circulatory system healthy. My personal thought on this is that weight lifting should not be dangerous with combined cardiac training...
This morning my resting pulse was 47 beats per minute and I give all credit to my more frequent, occasional running and Muay Thai! I didn't do serious cardiac training for a long time after my knee surgery and my pulse was always between 60 - 70 beats per minute. The resting pulse rate decreases with cardiac training because as the heart gets stronger, it doesn't have to pump as often to circulate the same amount of blood through the body.
To oppose what I just promoted a bit, below is my week in exercise! I both squatted and deadlifted 50 kilos, not that much maybe, but my personal best so far and I'm very happy. An excellent week workout-wise, except of course that I would have liked to do more cardio.
Wed: Muay Thai