Unfortunately, there’s no way around it: running takes a toll on the body. With every step you take, your landing leg absorbs a force of about two-and-a-half times your body weight, according to Jay Dicharry, an Oregon-based physical therapist and author of Running Rewired. To avoid some of that, it’s smart to incorporate low-impact cardio exercises into your routine.
“High-impact activities such as running and plyometrics cause a lot of biomechanical stress on the legs,” Dicharry says. That “biomechanical” stress refers to the amount of pounding that our bones, muscles, tendons, and ligaments endure during an activity, he explains. To keep all those body parts healthy while still working on your fitness, you can turn to low-impact cardio workouts—an ideal way to mix up the way you train.
What is low-impact cardio exercise?
The primary difference between high-impact and low-impact exercise is that the latter causes very little biomechanical stress on our bodies, since it doesn’t involve jumping and landing, Dicharry explains. But the two activities are similar in that they both cause physiological stress, the amount of strain on our cardiorespiratory system (or our hearts and lungs) during exercise. This means low-impact exercises can improve your cardio fitness just as well as high-impact exercises.
The thing about low-impact cardio is that just because you keep one foot on the ground the entire time, doesn’t mean the workouts are low-intensity too—they still get the heart rate up and make you breathe heavy.
What are the benefits of low-impact cardio workouts?
“For low-mileage runners, doing low-impact cross-training instead of extra runs is a good way to stay in shape and prevent injuries,” says Kurt Ward, assistant track and cross-country coach at Weber State University.
Because one of his college athletes has suffered stress fractures in the past, Ward instructs her to only run three to four workouts per week, and train on the Alter-G (anti-gravity) treadmill, elliptical, bike, or in the pool on the other days to protect her legs. Though her weekly mileage hardly ever exceeds 30 miles, she still finishes alongside her top teammates in cross-country races, thanks in part to the cardio fitness she has sustained and gained through the cross-training.
Maybe you think a low-impact cardio workout doesn’t count as a run day, but here’s the good news: You’re sweating and burning calories and giving the joints you rely on to run a rest.
“Running requires you to stabilize against very high forces each and every stride. Little imbalances in the way you stabilize your body suffer under running,” Dicharry says. “While the best way to fix those imbalances is to focus on a comprehensive strength and stability plan... supplementing some of your weekly time training with low-impact cardio means less stress on your body through running,” and less time exacerbating those imbalances.
Even better: Switching up your cardio workout trains your body in new ways that make you stronger and more injury-proof when you hit the road. “Running three hours a week and doing two hours of low-impact cardio is still five hours, and that means less body stress and less injury risk,” Dicharry says. “Running loads your body in very specific ways. The better you get at controlling your body in different ways (like with swimming and rowing) the better rotational control and postural control you’ll have when you run. When you learn new skills from different sports, there is carry over to your body awareness in running.”
So whether you’re sidelined with an injury or simply want a low-risk way to add more volume to your training, low-impact cardio exercises are golden. We spoke to experts about the best ones for runners and how you can benefit from each. Here’s the scoop.
The Best Activities for Low-Impact Cardio
Of all the activities on this list, swimming causes the least impact on the body, Dicharry says. For runners coping with injuries such as stress fractures, knee issues, or arthritis, working out in the pool—whether you’re swimming laps or aqua jogging—is often a safer option for cross-training than using the bike or elliptical, which put more strain on the lower body.
“When one of our athletes is recovering from an injury, she usually starts back in the pool, then progresses to the bike or elliptical as she heals,” Ward says.
While being nearly weightless in the water allows runners’ bones and ligaments to rest, upper and lower body muscles—including your arms, obliques, hip flexors, and core—are engaged when we swim, and our hearts and lungs have to work hard to pump blood to all of those areas, which is why it’s a great cardio exercise, Dicharry explains.
“Swimming forces you to work on breath control, which is important for runners,” he says. To improve your lung capacity, you can try breathing drills, like alternating laps of breathing every three, five, and seven strokes.
To make the most out of swimming, Dicharry suggests doing high-intensity intervals like fast 100- or 200-meter repeats with little rest in between each repeat. The up-tempo sets will rev up your heart rate in the same way track intervals would, but without the impact, he says.
Runners tend to gravitate to the elliptical because it mimics the motion of running the most, but Dicharry points out that because your feet don’t leave the machine’s pedals, it doesn’t cause the same biomechanical stress that running does, meaning you aren’t gaining the elastic strength you need for running. Still, he notes that the exercise does build some muscle memory in the quads, hamstrings, calves, and arms that can translate out on the road.
Like swimming, training on an elliptical also challenges the heart and lungs—and you can get an even greater cardio boost by doing sprints on the machine, Dicharry says. The physical therapist notes that runners usually make the mistake of cranking the resistance up on the elliptical in order to get a better workout, but they’re better off aiming for a higher cadence at a lower gear.
“When you crank the resistance up, you’re basically climbing up a flight of stairs,” he says. “Going faster at an easier resistance will raise your heart rate more, and the movement also resembles running more closely.”
One more thing to remember: Don’t use the arm handles. “This forces you to stabilize on your own,” Dicharry says.
Whether you ride outdoors or indoors (on a stationary bike or trainer), cycling is a great way to boost your cardio fitness and strengthen your quads, hamstrings, and glutes—all of which are used in running—without putting a lot of pressure on your joints, says Dicharry, who’s an avid cyclist himself.
One downfall of cycling, though, is that it doesn’t strengthen your entire body as well as other cross-training exercises. “I’ve coached cyclists who are very cardiovascularly fit, but are are weak in their cores and upper bodies since they haven’t developed those muscles very much,” Dicharry says. He recommends supplementing your indoor cycling with strength-training exercises that target your core.
“Oftentimes, cross-training is done alone, which can be tough mentally,” Ward says. So having a virtual indoor cycling class or a few friends to (virtually) work out with is good motivation to get it done.
This seated, pushing-and-pulling exercise works up a serious sweat, and it also strengthens areas of the body that are often weak in runners, such as glutes, hamstrings, and both upper and lower back muscles, Dicharry explains.
“Runners tend to be all-quad, and don’t normally tap into their back muscles,” he says. “Incorporating rowing into your routine can build the backs of your legs, which can help prevent injuries in the future.”
He notes that it’s important to maintain proper form on an indoor rower, however, so you don’t tweak something during your cross-training. To start, sit with your feet in the stirrups and your knees bent. Reach forward to grab the handle, then drive your feet into the stirrups and straighten legs (but don’t lock out knees) to drive yourself back. Keep your back and abs tight as you lean your torso back. At this point, pull the handle to your ribcage by bending at the elbows. Finally, straighten your arms while you slide back into the starting position.
The Bottom Line
Low-impact cardio workouts can be a great alternative or supplement to running as they allow you to build a strong aerobic base without punishing your legs and joints with more pounding. For injured athletes who can’t run, doing activities that don’t strain your bones and joints is key for maintaining fitness while you’re sidelined. Just remember to supplement the cardio workouts with rehab exercises and strength training to prevent the injury from coming back.