Go and read it, but a few quotes:
Research from the K.G. Jebsen Center goes well beyond the Dallas findings, and shows that fit 50-year olds can be as fit as 20-year olds who don't exercise much. But exercise -- how much, and how intense -- is the key to maintaining this fitness. When the Jebsen Center researchers looked at the importance of the intensity of exercise versus the duration, intensity was far more important than duration in determining peak oxygen uptake.
They have also looked at the benefits of high intensity exercise in the form of interval training -- where four or more short periods (typically 4 minutes) of very high intensity exercise are followed by a similar number of short periods of lower intensity exercise. This approach, called 4x4 interval training, is a quick way to increase your overall fitness, research from the Jebsen Center has confirmed.
The center's research shows that maintaining some level of physical activity is important. The benefit from having been active when young is small if you are inactive now. "Even if you were highly active at a young age, you have to keep being active to get the health benefits from it," says Professor Wisloff.
So how do K.G. Jebsen Center researchers stay fit, given all that they know? Many incorporate exercise into their daily routines. Aspenes -- a 33-year-old father of three, with a full time job now at the Norwegian Directorate of Health -- is lucky because he can ride his bicycle to and from work, which in hilly Trondheim, means that at least part of the ride is up some pretty steep hills. That's an advantage for interval training, he says, because "I ride like hell up the hills."