Physorg.com, a science website, reports that cardiovascular fitness can be improved, and the risk of diabetes reduced, by brief, high intensity workouts:
A regular high-intensity, three-minute workout has a significant effect on the body’s ability to process sugars. Research published in the open access journal BMC Endocrine Disorders shows that a brief but intense exercise session every couple of days may be the best way to cut the risk of diabetes.
According to the article:
The subjects in this trial used exercise bikes to perform a quick sprint at their highest possible intensity.
Apparently for only three minutes.
No more excuses not to exercise?
Prometheus Unbound 
I disagree with this article. The American Heart Association and the American College of Sports Medicine does not say that you have to spend hours a week to get any results. The latest report from 2008 states that exercise bouts as small as 10 minutes at a time, totaling 30 minutes a day or more, 3-5 days a week is all it takes. This article is misleading!
Antonetta,
I think that you are perhaps latching onto the phrase, “the best way” to cut diabetes risk, in which case I agree with you.
BUT the article that I linked to says that the researchers took sedentary people (couch potatoes) and got them to do this. Apparently, these three minute sprints are better than nothing—and have substantial measurable effects on the otherwise sedentary.
But I agree that this three minute activity, combined with other exercise and eating right, is surely far more ideal (healthwise) than just doing the three minute “sprint” alone.
Lastly, I think you have a good eye for bullshit—catching, for example, the “straw man” exageration of “hours” supposedly being required for fitness (if one goes by mainstream advice).
You remind us that even science news websites can be prone to excitable and misleading language (in an attempt to catch readers).
—Santi