Sometimes it seems that all I hear about is the magic of high intensity interval training (HITT). This protocol alternates short periods of intense exercise with longer periods of moderate recovery periods (think sprinting 30 seconds, then walking or jogging at an easy pace for one minute, and repeating for about 20 minutes total) and promises results in as little time as possible. But the concept can be daunting for anyone who is just starting a workout program, recovering from an injury or surgery, or packing a little more weight than ideal.
So I’m here to preach the gospel of LISS: Low intensity steady state.
LISS exercise is any repetitive motion for 30 to 45 minutes at 50 to 60 percent of your maximum heart rate (MHR), according to sports medicine specialist and physical therapist Kevin McGuinness, who practices at Washington Orthopaedics & Sports Medicine. Typically, this refers to such activities as walking, swimming, or even jogging or biking at an easy pace.
“LISS is any activity that gets your heart rate up just a little bit and for a longer period of time,” McGuinness says. If it sounds familiar, that’s not surprising: Before the recent popularity of HIIT, McGuinness says, low intensity exercise was simply called “cardio.”
McGuinness says in addition to improving your mood and cognition and helping you control your blood sugar, “LISS is one of the best ways to maintain a level of fitness.”
Assuming your physician has approved your fitness plan, here’s how to practice LISS exercise. Calculate your maximum heart rate (MHR) by subtracting your age from the number 220. For example, if you are 49 years old, your MHR would be about 171 beats per minute. To stay within the 50 to 60 percent range, then, you would want to keep your MHR between 85 and 115 bpm, McGuinness says.
There are plenty of devices that help you monitor your heart rate, but you can also do this by taking your pulse and counting the beats for 60 seconds (or for 15 seconds and multiplying by four). Or see if you can hold your end of a conversation comfortably. If you can, you’re working within the optimal range for LISS.
LISS is a great option for first-time exercisers, McGuinness says, especially those who might be intimidated or limited in their ability to engage in higher intensity exercise.
“Whether it’s a more approachable form of exercise or whether their weight makes that type of exercise too painful to complete on a regular basis, low intensity exercise is a much friendlier, easier to try, version of cardiovascular exercise for the uninitiated,” he says.
Because it is associated with fewer injuries, LISS is particularly appropriate for individuals recovering from an injury affecting a weight-bearing part of the body, such as an ankle, or the knee or hip, according to McGuinness.
“Getting your heart rate up again and reintroducing some of the benefits of exercise without the potential pitfalls and risks that come with higher intensity exercise make LISS an ideal option for people recovering and rehabbing injuries,” he says.
It can also be the answer for people recovering from surgery. When her oral surgeon told Liza Himmelman of Chevy Chase, Maryland, that she would need to stop exercising for at least two weeks after an upcoming surgical procedure, she panicked. She didn’t want to give up the progress she’d made through her fitness routine: Heavy weightlifting two days a week with a trainer; lighter, self-guided weightlifting two other days; and a once-a-week spinning class.
“I want to maintain my health, which took me six months to get,” the 49-year-old told me. “At my age, I can’t take two weeks off!”
Liza and were I commiserating about this because I haven’t been able to run since March 11, when I developed plantar fasciitis during a half-marathon. It’s a condition that can take weeks, if not months, to heal, and, unlike some injuries, you cannot run, no matter how easy, through your rehab. I worried that in addition to losing my level of fitness, I’d put on weight.
The trainer we share talked up the benefits of LISS for both of us. For me, he designed LISS walking workouts. For Liza, he created a lifting plan that wouldn’t unduly raise her heart rate. This approach involved lifting lighter weights, lifting more slowly and taking more time between sets.
LISS isn’t helpful for only neophyte and recovering fitness buffs, however, McGuinness says. It has a place in the exercise program of nearly everyone, including higher-level athletes, who may use a LISS day, or “recovery day,” to tone down the mileage and the intensity to take pressure off the joints but still keep moving to make sure they don’t stiffen up.
Varying the level of intensity in any exercise program can help you avoid burnout and offer adequate time to recover while still being active, McGuinness says. But in LISS, as in any exercise program, it’s also important to vary the stimulus. One of the physiological adaptations of exercise is that the body becomes more energy efficient and may not burn as many calories to do the same volume of exercise after the body adapted to it.
“If you go out for a one-hour walk five days a week and always on flat ground and never change the pace, eventually that exercise is going to be less useful than it used to be,” McGuinness says. He recommends that you consider changing that one hour of walking to 40 minutes of easy bicycle riding around the neighborhood. Or you could change the distance or change the intensity by varying it within the confines of LISS, to retain your level of fitness. In my case, for example, that includes walking the hills in my neighborhood until I can run again.
As McGuinness puts it, “There’s value in staying at a good place where you can comfortably exercise and maintain your body composition and not hurt yourself.”