HIIT (high-intensity interval training)
HIIT is interval training with short, very intense bursts and rest breaks – short and effective, but only sensible if you have a fitness base and a healthy heart.
Ausführlich erklärt
HIIT stands for “high-intensity interval training”: you alternate short, very hard phases with recovery breaks – for example 30 seconds fast, 60 seconds easy, for eight rounds. In the intense phases you're at 85 to 95% of your maximum heart rate; talking is no longer possible.
The appeal of HIIT is the time it saves: 15 to 25 minutes including the warm-up is enough. Reviews (such as Wewege et al., 2017) show that over several weeks HIIT reduces body fat about as much as longer, steady endurance training – with around 40% less training time. It also improves oxygen uptake and insulin sensitivity (how well your cells absorb sugar from the blood) particularly quickly.
The catch: HIIT is hard work and puts a lot of strain on joints, tendons and the nervous system. One or two sessions a week are enough, with at least 48 hours of recovery for your muscles in between. Beginners should first spend four to eight weeks building up base endurance. If you're very overweight or have cardiovascular problems, high blood pressure or joint pain, talk to your doctor first – in that case brisk walking is the smarter choice.
The most famous variant is the Tabata protocol: 20 seconds all-out, 10 seconds rest, eight rounds – four minutes in total. Japanese researcher Izumi Tabata developed it in 1996 for speed skaters on the national team, in other words for elite athletes. For home use, gentler ratios such as 1:2 or 1:3 (work to rest) are better.
Children don't need stopwatch HIIT – their natural play has always been interval training: sprinting, catching their breath, dashing off again. Playing tag is the most honest HIIT in the world.