The concept of high-intensity interval training (repeated brief bouts of high intensity exercise followed by rest intervals, typically referred to as HIIT) has been around for a while now. Early studies found HIIT is equally effective at improving fitness as performing similar exercise at a lower intensity for a longer period of time, which is great news for anyone short on time.
HIIT sessions typically last 20-30 minutes, meaning you would only need to invest a maximum of 90 minutes exercising per week to get similar effects to the 150 minutes of moderate exercise per week currently recommended by the UK government.
From gym classes to spin sessions and CrossFit, HIIT protocols have become commonplace in recent years. And unlike a lot of other fitness fads, HIIT looks like it’s here to stay. Research finds that people who do HIIT often enjoy it more and stick with it longer than other types of exercise. One study even found people who do HIIT typically report improved perceptions of overall health and vitality.
But despite HIIT being a time efficient way to stay in shape, some of us still can't find the time to train, while going to the gym may also present barriers for some (not least thanks to the yo-yoing lockdown rules we’ve all been subjected to).
This is where ‘exercise snacking’ comes in. Borrowing its name from the, often unhealthy, habit of eating randomly throughout the day, exercise snacking destroys the idea that we need to train in planned, lengthy bouts.
Two separate, recent studies asked their participants to sprint at full pelt for three 20-second bursts. Both studies saw an overall fitness improvement of around 5% in their participants within weeks, which is very impressive when you consider that’s comparable to people doing traditional HIIT protocols.
Interestingly, the settings where participants performed the exercise differed between the two studies. One study had its participants exercise in a laboratory on a stationary bike, whereas the other had its participants sprinting up three flights of stairs (60 stairs). The benefit of these differing approaches, is that it proves exercise snacking works, irrespective of the setting.
The practical applications of this are huge. After all, we don't all have stationary bikes at home, but there are stairs in most workplaces and homes. Sure, the typical British house doesn’t have 60 stairs, but the exercise can be broken down into even more bitesize ‘snacks’ and still be effective.
We recently performed a study looking at a home-based stair-climbing protocol. We asked our participants to run as fast as they could up a flight of stairs, then walk back down and run up again until they completed 20 seconds of exercise (i.e. 3-4 runs up a single flight of stairs). This was repeated three times a day for three days a week.
Our participants were keen to continue with this exercise even after the study ended. Before suggesting that everyone starts running up stairs, however, I should mention that such an activity does have risks! Trips and falls are not uncommon when walking up stairs, let alone running, so do be careful if trying this yourself.
Having said that, none of our participants reported any falls or injuries, but they were all young and relatively fit. I wouldn't recommend elderly or unfit people to start running up stairs, but as the other study found, stationary bikes also work, as would treadmills or even sprinting in the park, especially if you can find a decent hill to take on.
On that note, it’s worth bearing in mind that sprinting (i.e. running at high-intensity) is relevant to each person’s abilities. An athlete will sprint at very high speeds, whereas an elderly frail person may only be able to walk at a slow pace. However, as long as both are pushing themselves, they are likely to achieve the expected results.
Moreover, we are now trialing a resistance exercise snacking protocol. Every hour, our participants complete as many repetitions as possible in 30 seconds of a resistance exercise (alternating between push-ups, squats, ab crunches, etc.). While it's very early to draw any conclusions, they seem to be enjoying it.
Even though evidence around exercise snacking is still limited, the research suggests it’s an effective way of improving fitness. This bitesize approach is especially important now, in the era of COVID-19, when “stay at home” orders limit mobility, and access to exercise facilities is limited.
It has already been said that 'Covid-19 will be followed by a deconditioning pandemic’ and exercise snacking could well be a useful tool to try and fight this. From now on, try to do 30 seconds of an intensive exercise between your meetings or as soon as you complete any task that had you sitting down for a while.
Dr Antonis Stavropoulos-Kalinoglou is a senior lecturer in sports and exercise physiology at Carnegie School of Sport, Leeds Beckett University.
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