The findings, published April 5 in the American Journal of Human Biology, suggest that brief, intense workouts offer a time-efficient way to reduce cardiovascular disease risk factors in teens, said study author Duncan Buchan, of the University of the West of Scotland, and his colleagues.
High-intensity Training (HIT) May Prevent Heart Disease
The study included 57 adolescent schoolchildren (47 boys and 10 girls) who were randomly assigned to high-intensity training (HIT) or moderate-intensity exercise groups.
Both groups did three exercise sessions a week for seven weeks. The high-intensity training (HIT) group's program consisted of a series of 20-meter sprints over 30 seconds, while the children in the moderate-intensity training (HIT) group ran steadily for 20 minutes.
By the end of the seven weeks, teens in the moderate-intensity group had completed a total of 420 minutes of exercise, compared to 63 minutes for those in the high-intensity training (HIT) group.
Estimated total energy expenditures per child were 4,410 kcal for those in the moderate-intensity training (HIT) group and 907.2 kcal for those in the high-intensity training (HIT) group.
Both groups of children showed significant improvements in body composition, cardio-respiratory fitness, blood pressure, and insulin resistance. But the teens in the high-intensity group achieved those health benefits with only 15% of the exercise time put in by those in the moderate-intensity group.
Further research is needed, since the study was a small study.
SOURCE: American Journal of Human Biology, news release, April 5, 2011