When it comes to exercise, what’s your excuse? Whether it’s lack of time, money or motivation – sometimes the lure of the sofa can just be too strong – it can be all too easy to put off that run for another day. But whatever your reason, it’s still recommended that adults aged between 19 and 64 should be getting at least 150 minutes of moderate intensity or 75 minutes of vigorous intensity exercise a week. This roughly works out at about half an hour of brisk walking or cycling five times a week.
While this doesn’t sound like a lot of exercise in the grand scheme of things, research shows that you could actually do even less exercise and still maintain a good level of fitness – with the use of high intensity interval training (HIIT).
A typical HIIT session involves doing multiple intervals, or bursts of relatively short, intense exercise separated by rest or light exercise, and can last anywhere between a few minutes, right up to half an hour. It tends to involve many forms of exercise such as cycling, running or even resistance based training. All of which can be completed in a typical gym or health club setting.
Although high intensity interval training has been around for a while, it is receiving increased attention from researchers. This is because of its “time efficient” approach and the many health benefits it can offer such as increased cardiovascular fitness, lower blood pressure and improved blood results like “glucose tolerance” – how the body deals with sugar throughout the day and “good” cholesterol.
The downside of the typical HIIT programme is the intensity of the exercise – HIIT sessions usually involve “maximal sprints” – such as running or cycling as fast as you can, for 30 seconds. These sprints can be tough to complete especially for a lesser trained participant. This means that although HIIT is effective at improving fitness, lots of people are put off actually doing it because of the intense levels of exercise required.
A different approach
This is why at the University of Hull we have developed a modified HIIT programme which offers the important health benefits often associated with prolonged exercise, while saving time and being easier to complete. In our research, we used lower intensity, longer intervals for the protocol – which are different to the short, very intense intervals of traditional HIIT.
The programme involves a 28-minute HIIT workout on a stationary bike, featuring five two minute intervals, with only ten minutes of “hard” work, and the remaining 18 minutes light exercise. Over six weeks, we compared three sessions a week of our 28-minute HIIT protocol, with a continuous moderate intensity cycling programme and a gym based resistance exercise programme – which were both 55 minutes in length.
We discovered that our 28-minute HIIT programme gave the same fitness improvements as the longer 55-minute moderate intensity cycling sessions. This was shown as a fitness increase of 13% over six weeks – and was measured by a VO₂max test of participants before and after the six-week training intervention. This exercise test allows us to measure how well the body is able to deliver oxygen to, and use oxygen in the working muscles during exercise. The higher the participant’s oxygen consumption (VO₂max), the fitter the participant is. So of course we would expect this value to increase after completing an exercise training intervention.
Getting fit with HIIT
Our training study adds to the growing body of evidence which suggests HIIT is effective at improving markers of health. Although it is still unclear why exactly HIIT works so effectively, researchers have been able to show that it activates similar biological pathways and mechanisms traditionally related to endurance type exercise – such as an increase in muscles ability to use oxygen.
But while HIIT does appear to be effective at improving markers of health, more research – especially larger studies looking at the safety, adherence rates and participant enjoyment – are needed. These studies could examine the real world potential and application of HIIT, as much of the current research is conducted under controlled laboratory conditions.
So while it is clear there is still a lot that is unknown about HIIT, what is known is that by using a modified HIIT protocol you may be able to increase your fitness while spending less time at the gym. And in a time poor world, where more people need to engage in regular physical activity, that is definitely not a bad thing.