The time-strapped, stressed-out and downright lazy among us have no doubt caught wind of the latest trend in fitness: micro workouts, which have surprising endorsements not just from personal trainers but from scientists too. And yet they seem to be onto something. “If you only have 15 minutes, many people might blow off traditional exercise and say they can’t get a quality workout in a short period of time,” says Martin Gibala, a professor of kinesiology at McMaster University in Ontario. “But brief, intense exercise is an effective way to improve your fitness and markers that may reduce risk for chronic diseases.” Gibala is researching just how low you can go, time-wise, to get a good workout, but for now he says that to get the full effect, you need to trade in duration for intensity: the shorter the workout, the tougher it should be. “There’s no free lunch here,” he says. “You really have to get out of your comfort zone and go hard.” In his research, Gibala often uses cycling because it’s low impact, but you can substitute any type of exercise that gets your heart rate up–be it running, jumping jacks, burpees or barre work.
A Workout for Every Schedule
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Go as hard as you can. Gibala’s team has shown that you can improve fitness in just 60 seconds.
The workout: Get on a stationary bike or treadmill. Give yourself a short warm-up and then pedal or run as fast as you can for one minute.
The benefit: Men and women who tried the one-minute workout for six weeks improved their endurance and lowered their blood pressure.
Do the seven-minute workout developed by scientists at McMaster University.
The workout: For 30 seconds each, do jumping jacks, a wall sit, push-ups, crunches, chair step-ups, squats, tricep dips, planks, running on the spot, lunges, push-ups with wide rotation and then side planks. Rest for 10 seconds between moves.
The benefit: The diversity of the exercises strengthens muscles throughout the body and improves heart rate.
Try a simple form of high-intensity interval training with the cardio of your choice.
The workout: Hop on a treadmill and run as fast as you can for 30 seconds, then lower the speed and jog for 30 seconds. Repeat 10 times.
The benefit: Even if you’re not running to build endurance, research shows, quick spurts of exercise can improve cardiac health.
Gibala’s research shows that 20 minutes is enough time to get a serious workout–if you’re willing to sweat.
The workout: Choose an exercise like biking, swimming or rowing, and do it at your full capacity for one minute. Back off for one minute and repeat the rotation 10 times.
The benefit: These intervals are shown to improve blood-vessel and heart function.
This appears in the January 26, 2015 issue of TIME.