The Addition of High Intensity Interval Training Reduces Cardiovascular Disease Risk Factors and Enhances Strength in Active, Healthy Adults

The guidelines for cardiovascular exercise intensity are not clear with respect to the optimal training protocols to reduce cardiovascular disease risk (CVD) as well as to enhance strength. At this time, it is impossible to deduce the independent effects of vigorous-intensity exercise from past studies as the volume of either physical activity duration or energy expended differed in comparison to moderate-intensity exercise. Our goal was to augment the literature focused on the potential benefits of high intensity training with novel methodology that includes trained adults in a group fitness environment. Vigorous intensity training may be a critical component of the physical activity prescription if active adults demonstrate decreases in CVD risk factors and increases in strength. We hypothesize that a 6-week high intensity group fitness intervention will produce beneficial effects on CVD risk factors by reducing body mass, total cholesterol, LDL-C, triglyceride concentration, and by enhancing lean body mass percentage, HDL-C, glucose tolerance, and maximal oxygen consumption as well as both upper and lower body strength. Eighty-four healthy adults, 50 women and 34 men, completed the 6-week intervention. Participants were randomly assigned to one of two groups; the first was a high intensity interval-training (GRIT) program, while the second was a moderate intensity-training (FIT) program. All participants completed 5 hours of fitness classes per week. We collected musculoskeletal and physiological data at the start and finish of the study. In support of our hypotheses, the GRIT group significantly reduced body mass, triglyceride concentration and enhanced lean body percentage, glucose tolerance, and maximal oxygen consumption in addition to all of the strength measures. These results illustrate a novel finding that individuals who already participate in the recommended physical activity guidelines can improve their health, fitness and strength with the addition of 2, 30-minute sessions of high intensity interval training per week.