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Because high-intensity interval training (HIIT) can take just 15 to 20 minutes for a full session, it tends to be an efficient addition to a workout routine, especially if you usually do steady-state cardio exercise like running or cycling.

But what if you need even more efficiency or you find regular HIIT workouts too demanding or exhausting? That's when REHIT can provide the training benefits you need, without skimping on progress or results.

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By now you're probably wondering, what does REHIT stand for exactly? Short for reduced-exertion, high-intensity interval training, REHIT is a form of exercise that combines the principles of HIIT but involves less work, according to Sabrena Jo, CPT, personal trainer and American Council on Exercise (ACE) senior director of science and research.

"While HIIT typically involves short bursts of intense exercise followed by brief recovery periods, which challenges the cardiorespiratory system and promotes metabolic adaptations, REHIT aims to achieve similar benefits through both shorter intervals and a shorter workout duration overall," she tells LIVESTRONG.com.

REHIT exercise also tends to include longer recovery periods, she adds. For example, a HIIT workout might have a 30-second rest between intervals, or even a shorter rest time — like a Tabata workout, which has 10 seconds of rest — but REHIT might have up to 3 minutes of recovery time between exercises.

Because of shorter workout duration, you'll likely be doing fewer exercises as well, in order to focus on just a few that can be done at high intensity. For comparison:

‌HIIT:‌ Between four to 10 exercises in a set, 30-second rest intervals between sets, about 20 minutes total workout time.

‌REHIT:‌ Between two to three exercises, 20-second high-intensity interval per exercise, 3-minute rest between sets, about 10 minutes total workout time.

"The main focus of REHIT is to provide a time-efficient and effective workout for people who may not be able to engage in prolonged high-intensity exercise," Jo says.

In addition to providing a faster workout in general, REHIT can be helpful for several types of exercisers, including those who are just getting started with working out and those who have physical limitations or other health concerns, Jo says.

"REHIT may be particularly useful for older adults, individuals with chronic conditions or those undergoing rehabilitation," she says.

If you're new to exercise, these brief sessions may be particularly valuable for helping you ramp up gradually to a longer HIIT round, and can give you an idea of what HIIT entails without depleting your energy completely.

In a small ACE-supported February 2019 study in the ‌International Journal of Environmental Research and Public Health,‌ REHIT was done using a stationary bike over a period of eight weeks and participants saw significant improvements in cardiorespiratory fitness and cardiometabolic health markers compared to those doing traditional, moderate-intensity continuous training.

For example, reductions in systolic blood pressure in the REHIT group were three times what they were for those doing continuous training. Also, REHIT participants reported better adherence to workout plans.

"Even in more modest amounts, such as a REHIT session, exercise can provide a range of benefits that go beyond endurance or cardiovascular function," John Gallucci, DPT, founder of JAG-ONE Physical Therapy in New Jersey, tells LIVESTRONG.com. "You can improve strength, flexibility, mood and balance, as well as get into the regular habit of exercise."

For those with chronic conditions who tend to feel weakness or fatigue doing everyday tasks, doing REHIT sessions can help mitigate those effects, Gallucci adds. That's true not just because of the exercises themselves, but because there's so much recovery time built into the sessions.

"The short rest periods of HIIT workouts can be draining if you're not used to them," he says. "Having more time to catch your breath and reset before the next, short round of exercises can be a boost, mentally and physically."

Nearly any type of exercise can be made into a REHIT interval, as long as you include a longer recovery afterward.

"A sample REHIT workout could consist of riding a bike three times each week for about 8 minutes total," Jo says. "That would include warmup, followed by an all-out sprint of 20 seconds and a 3-minute recovery period, then another sprint and recovery period, and then a cooldown."

Although it might seem like doing just two 20-second intervals in a workout wouldn't do much, the ACE notes that REHIT workouts can create a sudden and substantial energy demand —which is an important part of metabolic function — compared to moderate-intensity continuous training. Plus, the efficiency means a workout can be easily wedged into busy schedules and vacations. After all, REHIT constitutes less than a minute of total effort and still promises benefits. Talk about a return on investment!

"With REHIT, you can have a challenging workout without pushing your body to the same extent as traditional HIIT," Jo says. "Truly, that makes it accessible to all."

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