Over the past few years, several articles, based on fitness research, indicate that short bursts of intense exercise can be as effective as longer periods of moderate exercise. One experiment even found that a single minute of “arduous” exercise had the same physiological benefit of 45 minutes of a more moderate workout. These benefits included improved strength, fitness and blood pressure. Other studies have shown that blood sugar levels respond well to intense interval training. But that’s not the full story. Intense, short bursts work only when the body is really pushed beyond its comfort level. And it’s not clear that ultra-short workouts provide all of the benefits of regular moderate exercise. Check with your doctor before changing your workout routine to add intensity.