Is just 12 minutes of HIIT really enough to be effective?
Most of us are feeling time-poor and tired, and the work/avoiding Covid/fitness juggle is only compounded by Christmas. Typically, it’s our workouts that take a backseat: who has the time, given most gym classes last around 45 minutes and require a stretch beforehand and a shower after?
But while long runs and gym sessions that work specifically on hypertrophy are brilliant for a host of reasons, super-short HIIT sessions definitely can play a role in making you stronger, fitter and healthier than ever. According to a study by Massachusetts General Hospital, you can improve your health and fitness with as little as 12 minutes’ worth of intense exercise.
The researchers claim that this has to do with beneficial shifts in the levels of “metabolites” circulating in the body during and after a short stint of high-intensity exercise, which, simply put, are by-products of your metabolism.
In order for researchers to gauge and examine this, 411 men and women were asked to complete 12 minutes of vigorous exercise, and their metabolites were measured before and immediately after via a blood test.
From the post-workout samples, “the research team detected favourable shifts in a number of metabolites for which resting levels were previously shown to be associated with cardiometabolic disease”. For example, after just 12 minutes of high-intensity exercise, there was an incredible 29% drop in levels of glutamate, “a key metabolite linked to heart disease, diabetes, and decreased longevity”. Levels of DMGV, a metabolite associated with increased risk of diabetes and liver disease, fell by a similarly impressive 18%.
Clearly, shorter bursts of intense exercise really can work wonders for your health, and training consistently in this manner has the potential to keep you in peak physical condition for longer.
There are, however, also more immediate benefits to working out in this way. We asked Dr Sarah Davies, a sports expert from Panacea Health, to expand on the “whys” and “hows” of the many short and long-term benefits of 12-minute bursts of intense exercise.
What are the benefits of 12-minute bursts of exercise?
Dr Davies explains that the change in metabolites caused by shorter bursts of intense exercise is driven by the mitochondria, which are responsible for powering almost all of the cells in the human body.
“When you challenge yourself in a workout, you ramp up the metabolic processes that happen mainly because high-intensity training makes the cells produce more mitochondria,” she says. This increase in what Dr Davies terms “mitochondrial density” has a lot of benefits, including reducing your risk of developing certain life-threatening diseases.
There are plenty of more localised benefits, too. “The increased production of cellular mitochondria makes your heart muscle more efficient, because you need less oxygen to carry out the same exercise as a result,” Dr Davies adds. Not only does this have a positive effect on your overall heart health, but it also means that you will be able to make progress faster than you would with longer periods of low or moderate-intensity exercise.
The muscles throughout your body also feel the effects, with the boost to the muscle cells’ mitochondria helping you to build muscle faster, perform better, and reap the greatest possible health gains in the fastest possible time.
How hard do you have to work for 12-minute bursts of exercise to be effective?
“You have to challenge your own individual exercise capability,” says Dr Davies, meaning that there isn’t a one-size-fits-all answer. “High-intensity training should, however, physically tire you out, with the benefit that overall time invested is low.”
It’s important to note that “if you have any family or personal history of heart or vascular illness, you should ask your doctor to advise if this is the correct form of exercise for you.”
What are the best forms of exercise to try in short bursts
If you want to give shorter bursts of exercise a try, then cardio workouts are the way to go. Dr Davies recommends cycling, running, cross-training and swimming in particular because these forms of exercise “use the large muscle groups throughout the body for maximum mitochondrial effect. They are also all fairly accessible, as the equipment is widely available and can be done at home or in the great outdoors.”
She also suggests aiming to do your short bursts of exercise two to three times a week in order to make the most of their many health benefits.
“However, you will need to start off slow and build your tolerance gradually to give your body time to adapt,” says Dr Davies. If you overdo it by pushing yourself too hard and too fast, you run the risk of injuring yourself, which will prevent you from achieving your goals.
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