HIIT is hot right now, at least that's where exercise science is at.
It's not hard to see why scientists – and people interested in fitness – are excited.
HIIT (high-intensity interval training) is as fast as it is famous right now and it's been getting faster.
There's the 45 minute work-out, popularised by F45, 30-minute classes, then, more recently, HIIT has accelerated into the seven-minute workout, the four-minute Tabata-based workout, the impossibly athletic 30-second workout and the recently researched one-minute workout.
The idea for all of them is the same: all the benefits of exercise are condensed in one extremely fell swoop.
"My whole philosophy on HIIT is you're giving your body a good blast," says Professor John Hawley, director, Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University.
Does it matter which version or length of time you do?
Emmanuelle Statamakis, Associate Professor of exercise, health and physical activity sport sciences at the University of Sydney, says that, presently, the research is not there to say one form is better than another.
"I do not think that anyone can make any assertions about comparisons of all these different HIIT regimes that have been published or publicised," Statamakis says.
"In the absence of a study comparing the HIIT regimes ... I would speculate that regimes like the 10-20-30 or the seven-minute ones will produce better results in the long term because they combine aerobic and anaerobic processes and higher total energy expenditure than the one-minute regime."
Hawley adds that shorter intervals can be easier to cope with psychologically.
"If you do 30 seconds or four minutes, it's probably not going to make a huge difference," Hawley says. "I can't tell you that x is better than y, any stimulation is better than none. It depends what the individual likes to do."
Whatever will get you moving is what will be the better workout.
"They all seem to work well to some extent and it is all down to factors like people's time availability and individual preferences," says Statamakis, adding that his concern is that it may be a struggle for sedentary people to go the distance with HIIT.
"Unfortunately the health benefits of exercise are transient and unless we come up with strategies to make exercise attractive/desirable for the masses of sedentary people and maximise the adherence to it there will be very little (if any) public health benefit," Statamakis says. "We should be mindful that this kind of training (HIIT) appeals mostly to relatively young individuals who are perhaps already active and fit.
"As it stands, very-high-intensity exertion will be too unpleasant and will not appeal to the large majority of sedentary middle-aged and older individuals who are most in need for lifestyle improvements because they are at imminent risk of developing chronic disease and even dying prematurely."
He points out that about 50 per cent of Australian adults do not meet the guidelines of 2.5 hours of brisk walking a week and nine out of 10 do not meet the twice-weekly strength-training guideline.
How to address this shortfall is a challenge many in the industry are attempting, particularly those researching HIIT, which is attractive given so many people (rightly or wrongly) claim that time constraints prevent them from meeting the guidelines.
Hawley points out that HIIT does not have to involve sprinting or working out like a maniac and still get the "afterburn" effect where the metabolic rate after exercise remains elevated.
"Walking briskly up a hill – that's HIT for 90 per cent of the population," he says, reminding that we can start slow(er) and build up – even with HIIT.
"I would even say in case of those who are overweight and obese, just walk up the stairs – that's enough to get most people out of breath.
"You just need to break inactivity patterns."
How long have you got?
10 MINUTES
One study found that short-term interval training using a 10-minute session involving one minute of hard exercise, three times per week, stimulated physiological changes linked to improved health in overweight adults
HOW TO DO IT: 2 min warm-up, 3×20 s all-out cycling efforts against a load corresponding to 0.05 kg/kg body mass, separated by 2 min of low-intensity cycling and 3 minute cool-down.
SEVEN MINUTES
The seven-minute set of 12 exercises, designed to work the entire body. "The exercise order allows for a total body exercise to significantly increase the heart rate while the lower, upper, and core exercises function to maintain the increased heart rate while developing strength," the workout's creators said.
The set, which they suggest repeating two to three times, is possible to be performed anywhere, without special equipment.
HOW TO DO IT: Perform each exercise for 30 seconds, working at about 80 per cent capacity and with 10-second breaks between each exercise, for a total of seven minutes. The exercises? Star jumps; wall sits (back against the wall with the knees bent at a 90-degree angle); push-ups; abdominal crunches; chair step-ups; squats; tricep dips; plank; running high-knees; push-up rotations and side plank.
FOUR MINUTES
One study from 2013 found that those who exercise to 90 per cent capacity (you should be able to say single words but be too puffed for sentences), for four-minute bursts, three times a week improved endurance, metabolic and cardiovascular health.
HOW TO DO IT: You can cycle, run or do stairs hard-out for four-minutes. The full program is to repeat this four times with three minutes of slow walking between, then a short cool-down.
ONE MINUTE
New research shows that in just one minute we can lower blood pressure and power-up energy cells.
HOW TO DO IT: The trick for gaining the benefits is to go hell-for-leather for that minute. Again, it doesn't really matter what form of hell-for-leather you do, but Hawley says the biggest bang for buck will be when people can use largest muscle mass (i.e. upper and lower body) at the same time.
