The title isn't original, but I thought it was clever. HIT is the acronym for high-intensity interval training. I have mentioned interval training -- which is the same thing as high-intensity interval training -- in some of my previous blog posts: Getting More from Less, Getting the Most from Your Workouts, and Exercise Your Options. In these blogs, I have talked about the great results you can get from interval training and the short amount of time you actually have to exercise.

I have been cautious in the past about bringing up HIT with sedentary friends because I thought that a baseline of physical fitness was required to try HIT. However, recent studies have been successfully conducted using HIT with sedentary individuals and "diseased populations" -- in this case, those with coronary artery disease, congestive heart failure, middle-aged people with diabetes and/or those who are obese. The most recent study used a low volume HIT model that would be more practical for a sedentary population. The model consists of ten, 60-second "sprints" at approximately 90% of maximal heart rate, with 60 seconds of recovery between each sprint. The method is time efficient in that only ten minutes of intense exercise is performed over a 20-minute training session.

The study found that compared to moderate-intensity, longer duration exercise, this new HIT model produces similar or even superior changes in a range of physiological, performance and health-related markers. Specifically HIT resulted in improved cardiovascular function, improved exercise performance, and increased capacity for whole-body and skeletal muscle to use fatty acids. The research indicates that "short intense bursts of activity with low-volume HIT induce large magnitude increases in cellular and peripheral vascular stress, while effectively 'insulating' the heart from those stresses due to the brief duration of the exercise bouts." The researchers emphasize the importance of the reduced exercise duration because “lack of time” remains one of the most commonly identified barriers to regular exercise participation. The researchers also identified research that people find HIT more enjoyable that longer duration, moderate intensity exercise.

Increasing the appeal of HIT is a study published in 2010 which found that HIT or SIT (Sprint Interval Training), as it was referred to in the study, increased insulin sensitivity in sedentary/recreationally active people. Data from the study showed that 16 minutes of high-intensity exercise over 14 days increases insulin sensitivity. The study also included HIT's effect on resting metabolic rate. Findings were the study participants did not use more energy when they were resting than they did before HIT training.

If you don't exercise because you don't have enough time, HIT may be something that you want to try. The benefit of exercise cannot not be underestimated. A new analysis of data from the global Interheart study found that both light and moderate on-the-job activity as well as leisure-time activity were associated with reduced risk of an heart attack compared to being sedentary. All levels physical activity were associated with reduced heart attack risk, ranging from 11% lower risk for mild exercise to 22% lower for moderate activity. Even participants getting less than 30 minutes of exercise a week were at lower risk than the completely sedentary.