Fast and furious

We live in a world where wishes have to come true fast and with the least amount of effort. To end up with that yearned for perfectly toned body, for the time being, there’s no other solution than to exercise. And take the health benefits in stride. To meet the desire for speed, using up as little time as possible, new training methods have been developed. High-intensity interval training is all the rage now.

Dedicating just a few minutes a day to this exercise routine will supposedly result in that fit and lean body you long for. But does high-intensity interval training live up to its promises? The jury is still out on that one. Does it suit everyone? Are there snags somewhere?

Even the question: what is high-intensity interval training, doesn’t generate an unambiguous answer. Wikipedia comes up with the following specification. High-intensity interval training (HIIT), also called high-intensity intermittent exercise (HIIE) or sprint interval training (SIT), is a cardiovascular exercise strategy alternating short periods of intense anaerobic exercise with less intense recovery periods, until too exhausted to continue. Contrary to aerobic exercise which builds up stamina in long duration, anaerobic exercise leads to greater performance in short duration.

The more intense the workout, the shorter it can be to have effects. (© Binyamin Mellish –

Though there is no universal HIIT session duration, these intense workouts typically last under 30 minutes, with times varying based on a participant’s current fitness level. The duration also depends on the intensity of the session. HIIT workouts improve athletic capacity and condition as well as glucose metabolism, according to Wikipedia.

To put it more practically, high-intensity interval training consist of a warm-up, followed by several repetitions of high intensity exercise. You can choose for instance cycling, rowing, running, stair climbing, uphill walking. The repetitions of high-intensity exercise, which should be done near your maximum heart rate capacity, are separated by medium-intensity exercise for recovery at about 50% of your heart rate capacity.  A common formula is a 2 : 1 ratio for work and recovery. For instance 30-40 seconds sprinting, followed by 15-20 seconds walking. The use of a clock or timer is recommended. The entire session may last from 4 till 30 minutes. And it should be ended by a cool down period of course!

High-intensity interval training is also popular among scientists. A lot of research has been done already to find out what the benefits of HIIT are. Everybody agrees that HIIT is effective in optimising the body’s ability to use and store blood sugar. It increases glucose metabolism as well as insulin sensitivity. Moderate intensity training has the same effect, but it takes longer to achieve.

HIIT may help ease arthritis pain, according to Norwegian researchers. It doesn’t seem to have adverse effects and results in less inflammation and reduced risk of cardiovascular disease.

Benefits have also been observed at cellular level. HIIT turns out to lead to a considerable increase in mitochondrial capacity. Mitochondria are our cells’ powerhouses. Keeping them healthy and active may help stave off old age. Another cellular effect was seen in colon cancer cells. Growth of these cells in colorectal cancer survivors was inhibited after sessions of HIIT.

High-intensity interval training has benefits all the way down to our cellular level. (© Martin Lopez –

Finnish researchers have been looking into endorphins, molecules that inhibit the communication of pain signals and that may produce a feeling of euphoria. They concluded that the release of exercise-induced endorphin in the brain depends on the intensity of the exercise. Apparently, HIIT does lead to endorphin release.

Canadian researchers noted an increase in brain-derived neurotrophic factor (BDNF) after HIIT. This protein supports growth, function, and survival of brain cells. From their research, they also concluded that HIIT boosts memory performance over a relatively short period of time. The same goes true for moderate intensity exercise, but, as said before, takes longer to achieve.

Opinions differ on whether high-intensity interval training contributes to weight loss. You can only burn so many calories in such a short period. In general, a change in diet, supported by exercise, is more effective to achieve weight loss.

New British research turned out that timing does matters in HIIT for increasing fitness. Apparently, it is 60 seconds intervals that do the trick. After 60 seconds of high-intensity exercise, 60 seconds of rest have to follow. Repeating these cycles for 6 to 10 times works best for improving fitness.

Although HIIT seems like an excellent way to workout for people limited by time constraints, there are downsides to this type of exercise. It generates higher rates of injury, especially in knees, ankles, and shoulders, and imposes higher cardiovascular stress. You should start out with a base level of fitness. High intensity interval training is not for couch potatoes. Many people do not have the required flexibility, mobility, core strength and muscles to perform HIIT exercises. It certainly isn’t suited for people who have a family history of heart disease, who suffer diabetes, high blood pressure, abnormal cholesterol levels, nor for people who smoke or who are obese.

There are downsides to HIIT. It imposes higher cardiovascular stress for instance. (© Pixabay –

HIIT may result in higher discomfort which makes it difficult to sustain. If you have to go all-out for as little as a few minutes and reep the benefits of a 45-60 minutes workout, there is a price to pay.

“That price is 100 percent intensity”, says professor of kinesiology Panteleimon Ekkekakis at Iowa State University. “It is undeniable that the experience will be unpleasant.”

While lack of time is a popular excuse, it really boils down to behaviour and people choosing to spend their free time doing something they enjoy more than exercise. “Given that most people do not adhere to a workout philosophy of ‘no pain, no gain’, condensing the duration will not make a difference”, according to Ekkekakis.

It seems high-intensity interval training might be only for healthy young people, but there are options for the general public. The University of Stirling in Scotland developed and easy protocol comprising of 10 minutes of easy pedalling interspersed with two 20 seconds intervals of all-out cycling sprints.

Home-based HIIT programs reduce barriers such as time and cost of going to the gym and increase adherence. They seem to give a more attainable exercise goal. Playing some upbeat music while exercising, turns out to be highly motivating, according to Canadian and British researchers. Humans have an innate tendency to synchronise their biological rhythm to musical rhythms. Fast tempo music can make rigorous workout seem less tough.

Although cleaning windows would be a good example of high-intensity incidental physical activity, don’t overdo it! (© Immortal shot –

A softer version of high-intensity training is called high-intensity incidental physical activity (HIIPA). The goal is to incorporate HIIT into everyday life to help people get the exercise they need. HIIPA is about regular incidental activities that get you huffing and puffing, if only for a few seconds. Such activities include washing the car, climbing the stairs, carrying groceries to your car that you parked at the edge of the carpark in stead of as close to the shop entrance as possible. Incorporating this kind of activities a few times a day – preferably 3-5 brief HIIPA sessions totalling 5-10 minutes per day – will generate health benefits and is more achievable for most people.

Will high-intensity interval training be here to stay or will it take the route into oblivion like many other fitness trends? In the end, it doesn’t matter much how you move. Do whatever suits you and what makes you feel good. As long as you do move!


Leopard © Pixabay –


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