Study Goal: The goal of this study1 was to test the effects of circuit training with and without behavioral intervention on reducing specific fat depots and other type 2 diabetes risk factors in overweight and obese adolescent Latino girls. The Latino girls were 14-18 years of age.
Circuit Training Format: The circuit training sessions were held on two non consecutive days per week. The circuit training (CT) was comprised of two different strength exercises for 1 minute each, followed by 2-3 minutes of cardio activity on a treadmill, elliptical machine, or aerobic movement. The exercise sessions included sound exercise principals of progressive overload for intensity, volume, repetitions, and speed. They also used sound principals of exercise order and selection, and participants wore heart rate monitors. The participants were to maintain a heart rate (HR) intensity between 70% and 85% throughout the session, even while strength training.
Comparative Groups and Assessments: The girls assigned to the CT plus behavioral intervention called motivational Interviewing (CT+MI) did the same CT as described above but also received 4 individual motivational interviewing and 4 group motivational interviewing sessions.
Thirty eight girls were ultimately selected for the study and completed at least 28 of the 32 sessions without missing two consecutive sessions (make up sessions were provided). Pre and post measurements were taken including a fasting blood draw, blood pressure and body composition measurements, a maximal VO2 estimate using a treadmill test, and upper and lower body strength measurements. Accelerometers were also used to measure habitual activity and a 3-day dietary record was taken and assessed.
Results: Change Compared to Control
Regarding changes in fat deposition (type of fat and location) there were significant decreases for both CT groups but increases for the control group, which didn't receive intervention. There were also significant improvements for both CT groups in metabolic parameters like fasting insulin levels compared to the control group, where these increased.
Conclusions: A circuit training system seems to be a good jump start to an exercise program for individuals who are overweight or obese. It is a good starter because overweight or obese initially cannot tolerate continuous cardiovascular work. The CT was in 2-minute bouts between each of the two strength exercises. This approach allowed the Latino girls to maintain an HR between 70%-85% and kept them moving, thus burning calories and developing fitness. It also decreases boredom and potential lack of focus. More similar studies need to be done with male adolescents to conclude that similar results could be expected.
When have you last jazzed up your metabolism? Why not try a circuit of your own at home or at the gym? Download your favorite music, use your stop watch for intervals and have fun getting fit and slimming down.
1Davis, N. (2011). Startup circuit training program reduces metabolic risk in Latino adolescents. Med Sci Sports Exerc, 43(11), 2195-2203.