New research from the University of Missouri-Columbia suggests intermittent exercise is more effective at lowering artery-blocking fat in the bloodstream than continuous exercise when exercising just 30 minutes.

MU researchers conducted the study to examine the effects of continuous versus intermittent exercise on triglyceride, a type of fat, levels in the bloodstream after subjects ate high-fat meals. The results show that people who engage in 30 minutes of exercise can achieve lower triglyceride levels after a high fat meal if they engage in short, separated bouts of exercise rather than one continuous bout.

The research team included professor of nutritional sciences Tom Thomas, post-doctorate fellow and Thomas Altena, assistant professor of nutritional sciences.

"Most Americans who exercise are exercising around 30 minutes a day," Thomas said. "Based on the results of the research, the intermittent approach would probably be best for most Americans at lowering fat in the bloodstream."

The researchers examined triglyceride levels following meals in inactive subjects. All subjects performed three different protocols on different days. On the control day, subjects ate a high-fat meal only. On a second visit, the subjects ate a high-fat meal following a session of continuous exercise. On another visit, the subjects ate a high-fat meal following a session of intermittent exercise in which the subjects exercised in 10-minute bouts separated by 20-minute rest periods.

Results indicated that peak triglyceride levels in the subjects who engaged in intermittent exercise before eating a high-fat meal were reduced by 27%. Those who engaged in continuous exercise reduced their triglyceride levels by 15%.

Thomas noted that exercising before eating was crucial for fat clearing, saying that the researchers believe muscle contraction during the exercise process stimulates a fat-clearing enzyme in the muscle.

According to previous research, the enzyme activity seems to peak about 12 hours after the session of exercise. In addition to showing what type of exercise is best, this information also could help someone determine what time is best for exercise. Since it's best to exercise 12 hours before eating a large or high-fat meal, those who eat large breakfasts could benefit more from exercise in the evening, while those who eat large dinners could benefit more from exercise in the morning.

However, Thomas said, the exercise effect on fat clearing does not last more than 24 hours, which suggests the need for daily physical activity to continuously stimulate the fat clearing system.

Source: Diabetes In Control.com: August 2004 Medicine & Science in Sports & Exercise.