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The Science Behind the New 4-Second Workout
High-intensity routines are brief and effective but not easy
Researchers are racing to figure out the minimum amount of exercise needed to improve fitness and health. Findings in multiple labs have generated tantalizing headlines suggesting all you need is one lousy minute of effort or, based on one new study, a mere four seconds.
The reality is quite different.
Brief but intense workouts can absolutely improve aerobic fitness, as well as muscle strength and power. In as little as 10 to 15 minutes, you can gain fitness benefits similar to an hour of traditional, less intense exercise. And evidence suggests you can spread the effort into even shorter “exercise snacks” throughout the day.
But these workouts are never easy, nor are they as minimalist as they might sound. The vigorous routines, called high-intensity interval training (HIIT), involve warmups and cool-downs and typically require multiple intervals of strenuous effort to achieve at least 80% of your maximum heart rate, a level that causes heavy breathing and makes normal conversation difficult. And sprint interval training (SIT) workouts, which are even more intense than HIIT, elicit the sort of effort you might summon to evade a marauding velociraptor.
