No time to exercise? 4-second interval training can increase your fitness, says science

As life reopens after the pandemic, some of us might feel like our schedules have filled up again very quickly, and that the opportunity to exercise is getting slimmer by the minute.  

If that sounds familiar, you’ll no doubt be pleased to learn that scientists have recently discovered that regular interval sessions of just four seconds work can significantly benefit your fitness and strength. 

The study published in the Medicine & Science in Sports & Exercise journal saw scientists gather 11 healthy men and women to push through 30 repetitions of four-second intervals on exercise bikes, with a gradual decrease in rest time every session. The participants did this three times a week for a duration of eight weeks.

By the end of the study the scientists found that the participants had added 13% to their aerobic fitness  and 17% to their muscular power, which was calculated by the volume of watts produced while pedalling the bike. 

Excitingly for those short on time, the results showed that workouts as short as 10 minutes were still effective. The cardiovascular stress progressively increased for the adults in the study as the recovery time decreased from 30 to 24 to 15 seconds between sets. This meant that the total training time dropped from 17 minutes to 10 minutes.

It’s easy enough to replicate the workouts performed in the study yourself - simply hop on a bike at your local gym, or else invest in one for use at home (see our pick of the  best exercise bikes to smash out a speedy workout before work).  

However, one of the great things about interval training is that it is super versatile and doesn’t have to be done on a bike. You may have heard the term ‘fartlek’, a form of interval training that runners use. The word originates from Sweden and means ‘speed play’, so runners essentially mix up the speeds that they run at between intervals of fast running, with breaks of slower running - you can read more about it in our guide on how to increase running speed. It is essential to keep your feet and body well supported when alternating between different running speeds, which  is why a pair of the best running shoes for women or best running shoes for men is a key investment.

HIIT workouts are another popular option. HIIT stands for high intensity interval training, and is one of the best exercises for weight loss.  Again, they take up so little time - this makes it hard to turn down a 30 minute morning HIIT workout. 

However, personal trainer Scott Laidler warns that we shouldn’t rely on four-second interval sessions everyday if we want to get to or maintain a consistent and sustainable level of fitness.   

Whilst he says that short interval training protocols can be really effective for weight loss, he adds that one very quick workout at one point of the day won’t necessarily offset the negative effects of being sedentary for the remainder of the day. 

“One should strive to strike a balance between making outcome-oriented workouts as effective as possible, minimising wasted effort and optimising time spent training with longer, less rigid activity such as hiking, cycling, yoga and sports,” says Laidler.