These are the words every runner dreads: “Stay off your feet to heal from an injury.” Besides missing out on your go-to source of endorphins and stress relief, your break from running could result in a loss of cardio fitness and strength. This is exactly when a runner might ask: Can I do cardio without my legs?

The short answer is yes, and the long answer is, having a go-to cardio workout that doesn’t rely on your legs is not only helpful cross-training, but will help you remain fit and healthy if you ever have to give your legs a rest.

Research shows that after about 12 days of inactivity, athletes are likely experience a dip in their endurance ability. This decline is likely due to a combination of factors, and every runner is different, but Dr Todd Buckingham, exercise physiologist at PTSportsPRO, tells Runner’s World that most people will see their VO2 max fall between 4 and 8 percent after about a week of no training. By two months, you may be looking at a 20 precent drop, and mitochondria (the “powerhouse” of the cell) declines at an even faster rate. “After one week [without training], mitochondrial content in the muscle fibres decreases by about 50 percent,” he adds.

Just because you can’t run or do weight-bearing exercises doesn’t mean you can’t do any workouts — in fact, you still have a lot of workout choices! “I’d encourage anyone in this situation to lean into whatever cross-training options they can do to maintain their cardiovascular fitness,” Matt Forsman, certified running coach and race organiser at Sasquatch Racing tells Runner’s World. “If your setback extends beyond a couple of weeks, you likely will lose some cardiovascular fitness, but sticking to a regular cross-training routine will help minimise this loss and better position you for a return to regular running.”

There is a caveat here, though: “It’s likely that whatever activity you switch to is one that you don’t currently do regularly. Just because you can run for an hour (or more) doesn’t mean you can swim for an hour right off the bat,” Forsman says. “Your body needs time to adapt to the particular demands of the activity you’re tackling.” Start slow and progress gradually, just as you would with running.

We asked Buckingham and Forsman for some of their favorite ways to remain active while staying off your feet. Below are seven options for cardio without legs.

1. Swimming
Swimming is at the top of both Buckingham and Forsman’s lists. “Swimming is my favourite form of upper-body cardio,” Forsman says. “It’s low impact. It’s a very solid cardiovascular workout. It’s also a full-body workout, so you’re engaging your arms and core in ways you likely don’t when you’re running.”

Water reduces the impact on the joints in the lower body, so it’s a great option for cross-training when you don’t have an injury such as a broken bone. Although, not all materials used to immobilise broken bones can be immersed in water.

It’s likely that if you’re dealing with a minor strain or sprain, you may be able to kick comfortably. If necessary, you can also immobilize one or both legs completely by using a pull buoy, a small piece of styrofoam you hold between the thighs. It helps keep the legs stationary and the hips buoyant so you can focus on your arm stroke.

Water is more resistant than air, so swimming is an overall strength builder, too, even if you’re only using your upper body.

2. Aqua Jogging
Like swimming, aqua jogging technically engages the lower body. But there are ways to take the legs out of the equation and still reap some of the cardio benefits — you’ll just need a flotation belt and access to a pool. “Keep your legs still if you can’t use them. Pumping your arms vigorously will get your heart rate up and keep you afloat,” Forsman says.

A recent research analysis on deep water running, a.k.a. aqua jogging, compared the effects of simulating running patterns in water to forms of “land-based” training, like running. The authors noted that, while more research was warranted, aqua jogging had a comparable impact on participants’ cardiorespiratory fitness, physical function, and quality of life.

3. Arm Ergometer
The arm ergometer or “arm crank” is an excellent option for anyone who is unable to use their legs. One systematic review of studies on arm crank exercise (ACE) among people with chronic spinal cord injuries found that ACE improved cardiorespiratory fitness in participants.

Additionally, using an arm ergometer can help develop arm and upper-body strength, which runners often overlook or deprioritise. In one pilot study, physically active participants added one to three ACE sessions to their regular training routine for 12 weeks. At the conclusion of the study, participants’ upper-body strength increased by an average of 13 percent.

A note of caution: cranking an arm ergometer looks easy, but it is quite a workout! “Your ability to output work is going to be significantly decreased on the arm bike than it is using your legs because the arms are a smaller muscle group than the legs,” Buckingham says. “You’ll probably find yourself getting tired very quickly. That just means you’re working.”

4. Rowing
Rowing is a proven method for improving cardiorespiratory fitness, and you likely can still use a rowing machine even if you can’t strap into the footbeds or push off with your legs.

“If you can’t use either leg, you can simply put your feet on either side of the rail and pull the handlebar exclusively with your arms. You won’t be able to row as fast or as far with each stroke. But, this is a good way to get your heart rate up without using your legs.” Forsman says. “If your injury is in just one leg, you can strap your good leg in and put the injured leg on a skateboard and roll it back and forth as you row. This gives you more of a full-body workout.”

Or, if you can, head outside and row an actual boat, like a kayak or a canoe. “You might not think of it as a workout, but you’re still getting in some cardio and upper body,” Buckingham says.

5. Upper-Body Strength Training
We tend to separate strength training from cardio and keep them in two separate categories — both in our brains and on our training schedules, but when lifting weights elevates your heart rate above a normal resting rate, it can count as cardio.

“Just do it at very light weight and high repetitions with very little rest in between [reps and sets],” Buckingham says. “You will find yourself getting out of breath moving from exercise to exercise.” This means that your body is using more oxygen to create energy to sustain your physical activity.

While you likely perform most upper-body exercises while standing, you can easily modify most movements by sitting on a bench or chair. For example, you can do biceps curls, overhead presses, triceps presses, front raises, lat pull-downs, and chest flys while seated.

6. Battle Ropes
There’s a reason battle ropes exercises are a high-intensity interval training (HIIT) staple: they’re intense. Research proves that battle ropes training quickly boosts your heart rate and increases your oxygen consumption.

They are still challenging if you do them performed seated in a chair or on the ground. So, don’t be discouraged if you feel spent after a couple of minutes. Remember that you can adjust the resistance by changing the weight of your rope, alternating between waves, swings, circles, and slams, and following up work intervals with more extended periods of rest.

7. Boxing
Experiencing feelings of frustration because you can’t run? Take it out on a punching bag.

“Boxing is a great workout for your arms and core. If you’re able to stand, you can punch a heavy bag or a speed bag. Just a few minutes of this will get your heart rate up in a hurry, “ Forsman says, noting that if you don’t have access to a punching bag, vigorous shadowboxing is a solid alternative.

“If standing up is not an option, you can still box or shadowbox while sitting in a chair,” he says.

READ MORE ON: cardio exercises cross-training fitness rowing machine swimming upper body