Short bouts of exercise reduce the risk of heart disease

Aug 6 2004

Accumulated, short bouts of exercise are more effective than continuous exercise for lowering fat and triglyceride levels in the bloodstream after eating.

This new research, presented in the August issue of Medicine & Science in Sports & Exercise®, the official scientific journal of the American College of Sports Medicine (ACSM), supports intermittent exercise, multiple 10-minute bouts that accumulate to at least 30 minutes a day on most, if not all, days of the week, as a way to reduce the risk of heart disease.

Single sessions of short and continuous bouts of exercise were studied to determine their effect on postprandial lipemia, a condition characterized by an excess of fat or lipids in the blood following a meal. Due to high dietary fat intake and multiple daily meals, most people have elevated triglyceride levels the majority of the day. Studies have shown that prolonged elevation of triglyceride levels increases fatty build-up in the blood vessels, which promote heart disease.

"People who cannot exercise for long durations due to low fitness levels or busy lifestyles don’t have to sit still and wait for a heart attack,” said Thomas S Altena, Ed.D., one of the study authors. “If we can encourage people to be active and accumulate at least 30 minutes of exercise in 10-minute bouts each day, it will have a positive effect on health overall, and more specifically, on the amount of fat in the bloodstream.”

Eighteen inactive adults with normal lipid profiles were studied to compare post-meal triglyceride levels after performing a single session of both continuous exercise and accumulated short bouts of exercise. Participants consumed a high-fat meal of known fat composition after jogging on a treadmill in continuous and intermittent bouts. Blood samples were collected prior to activity and every two hours during the activity period to measure lipid profiles.

Results indicate that intermittent bouts of exercise reduced blood triglyceride levels more effectively than continuous exercise or no exercise at all. Researchers believe this is because each short exercise bout may provide a slight increase in metabolism.

"If short exercise bouts are repeatedly performed throughout the day, they accumulate; thus, the amount of calories burned after each exercise session likely increases. Compared to a single session of exercise equal in duration, intensity, and caloric expenditure, our research indicates that regular repetition of short exercise bouts, which add up during a day, have a unique and positive effect on metabolism,” said Altena.

The research team from Southwest Missouri State University and the University of Missouri emphasized these results are only applicable to people not participating in regular exercise. It is unknown at this time whether 30 minutes performed continuously or intermittently is adequate to reduce fat in the bloodstream for those involved in a regular exercise program.

The American College of Sports Medicine is the largest sports medicine and exercise science organization in the world. More than 20,000 International, National, and Regional members are dedicated to advancing and integrating scientific research to provide educational and practical applications of exercise science and sports medicine.