It is well documented that aerobic exercise has a marked impact on the risk for cardiovascular disease. The training provides specific benefits by improving the blood lipid profile, reducing blood pressure and inflammatory markers, and enhancing endothelial function within vascular structures (among others). These benefits occur at some level with regular participation in low- to moderate-intensity continuous exercise, with the higher-end of the intensities providing the greatest benefits. Interestingly, most exercise programs prescribed for fat reduction involve steady-state aerobic exercise in the fat-burning zone, being around 65% of the participant's VO2max.
More recently, exercise participation by motivated fitness enthusiasts has shifted toward short-duration, high-intensity exercise. In a recent investigation published in the journal Australian Family Physician, investigators from the University of Notre Dame, School of Medicine compared the benefits of traditional aerobic exercise with aerobic high-intensity interval training (HIIT). The intervals used required the performance of repeated high-intensity work for 30 seconds to several minutes, separated by 1-5 minutes of varied recovery (either no or low-intensity exercise).
The researchers found that the aerobic HIIT was associated with increased participant compliance and improved cardiovascular and metabolic outcomes, and appears to be suitable for implementation in both healthy and medically-cleared populations. Expectedly, HIIT training reduces the total exercise time compared to steady-state training upon comparisons of oxygen consumption. Prior investigations have shown adaptations associated with intense intervals demonstrate a more than 20% faster adaptation rate compared to steady state training at the same caloric expenditure.
The fitness professional must understand that aerobic HIIT training requires acclimation by most participants. While many of the popular pre-formatted circuits, boot camps, and related types of exercise are contraindicated in certain populations, aerobic HIIT can be modified to address most participants' capabilities. In some cases however, this may require specific assessment or instruction before commencing the program.