You want to get started on an actual cardio routine — one you’ll, you know, actually stick with for more than two days. But everyone gives you different advice. Some swear that treadmills will kill your muscles, but others promise that smart programming won’t put your hard-earned gains at risk. How do you sort out the noise? Here’s your ultimate guide to cycling versus running.

Cycling Vs. Running

Before you decide to invest in cycling or running shoes, I want to reassure you: Cycling and running are both fantastic forms of cardio exercise that can boost your cardiovascular and mental health. You don’t have to choose one or the other. They’ll both serve you well, granted in slightly different ways.

[Read More: The Best Leg Exercises for Muscle & Strength, According to a PhD]

But since you asked (otherwise, you wouldn’t be reading this), I’m going to break things down into fitness goals for you. Do you want to lose weight, build muscle, or increase strength? One may win over the other. I’ll also dive into which is more efficient for different populations, how each relates to injury recovery, and what the science says about each activity and heart health.

For Efficiency

When deciding how efficient a cardio workout is, consider the equipment you may need, how long it takes to reach the same output or intensity, and how feasible it is for different fitness levels. 

[Read More: Expert Tested: The Best Treadmills for Running]

Burning calories isn’t always the best indicator of a solid workout, but it helps show you how hard you may be working in the same amount of time, so I’ll include those figures, too.

Cycling:

• Equipment Needed: You’ll need to own or rent a regular bike and safety gear for outdoor cycling or hop on a stationary exercise bike for indoor cycling. Some people like cycling shoes for spin classes.
• Amount of Time and Calories Burned: The number of calories you burn during exercise depends on your body weight and other factors. The Centers for Disease Control and Prevention (CDC) states the number of calories a 154-pound person may burn on a 30-minute and one-hour bike ride at different speeds. (1)

• Level of Difficulty in Reaching Intensity: One of the benefits of cycling is that even beginners can reach a high intensity, especially on a stationary bike. Solid form still matters, but you may be able to pedal faster and with more resistance — even at a lower fitness level. It’s also easy for advanced athletes to scale up by cranking up the resistance, trying high-intensity interval training (HIIT) cycling workouts, and alternating sitting with standing.

[Read More: The Benefits of Exercise Bikes (Plus Workouts From a Personal Trainer)]

Running:

• Equipment Needed: You’ll need proper running shoes. Other than that, you can run on a treadmill or outside. Many people get into running because it is free and relatively accessible when you just step out of your building and into your workout.
• Amount of Time and Calories Burned: The CDC gives the following number of calories a 154-pound person may burn running. They only list the amounts for running at five miles per hour, and some runners may run faster (or slower). Still, it gives you an idea. (1)

• Level of Difficulty in Reaching Intensity: Running burns more calories than cycling, but you need to be at a fitness level that is high enough to achieve it. Running for 30 or 60 minutes without stopping is challenging for a beginner, and even for more experienced runners.

The Winner: 

• Running is more efficient for intermediate and advanced runners. You only need a pair of shoes and your body weight, and you’ll burn more calories and work harder in the same amount of time as a comparable bike ride.
• Cycling is more efficient for the general population, beginners, or otherwise fit people who are new to running. You can burn as much energy on a bike at a lower fitness goals.

For Weight Loss

If you have a weight loss goal, the general theory is to burn more calories than you take in to increase your total daily energy expenditure (TDEE). You might assume that running is best for weight loss since it can burn more calories. Still, it’s more complicated than the cold hard numbers.

Cycling:

• Low-Impact: Cycling is a low-impact activity. Your feet never leave the pedals; you don’t have to support your body weight. If you have a weight loss goal or are at a heavier weight, starting with a non-weight-bearing exercise like cycling may be more comfortable. 
• Calories Burned: Since cycling causes less impact on your joints, you can withstand a longer period of cycling to burn the same amount of calories you could do on a shorter, high-impact run.
• Moderate Intensity for Weight Loss: You can get a great cycling workout at a moderate intensity. Some research suggests that people with obesity new to exercise may enjoy moderate-intensity exercise more than high-intensity exercise because it has a lower rate of perceived exertion (RPE). (2)

Running:

• Calories Burned: Advanced runners can burn more calories in a fast, long-distance run, which could lead to more weight loss overall. 
• High-Impact Activity: Running is a high-impact activity. Each time your heel strikes the ground, your joints take on the force of two to three times your body weight. For people at higher weights, a higher impact may increase the risk of injury. (3)(4)
• High-Intensity: The high-impact, high-intensity nature of running may also lead to more weight loss. 

[Read More: The Best Incline Treadmills on the Market]

The Winner: All things being equal, running burns more calories, but cycling is lower impact, gentler on joints, and might be safer for higher-weight people who may have weight loss goals. 

For Strength

Though you’re not lifting heavy weights for a few reps — a classic component of strength training workouts — both cycling and running may increase your strength. You’ll get stronger at what you do consistently. Some populations may see more strength gains than others, though.

[Read More: The Best Air Bikes for Your Home Gym]

Cycling:

• Strengthens Leg Muscles: Cycling, especially with resistance or uphill, will strengthen your leg muscles. Your quadriceps (cycling is particularly quad-heavy), hamstrings, glutes, and calves all need to engage in pushing and pulling the pedals. You’ll also get some upper body work in an indoor cycling class. 
• Older Adults: One review of studies suggests that older adults may build more strength during cycling than younger adults. Younger adults may gain some strength by doing HIIT exercise bike workouts, but moderate intensity works for older folks. (5)

Running:

• High-Impact Weight-Bearing Exercise: High-impact, weight-bearing exercise like running will likely build more strength than cycling since you need to support your total body weight while powering yourself through a run.
• Bone Health: Medical professionals may advise older adults at risk of osteopenia (low bone mineral density or BMD) or osteoporosis (a more severe loss of BMD) to do weight-bearing cardio exercise and resistance training. Researchers have investigated running versus cycling and BMD.
  • One systematic review found that cycling is less beneficial for bone health than running and other weight-bearing cardio exercises. Runners had a higher BMD in their lumbar spines than cyclists. However, cycling is more beneficial to bone health than a sedentary lifestyle. (6)
  • Another study of cyclists and runners assigned male at birth found that the cyclists were seven times more likely to have lumbar spine osteopenia and lower BMD than runners. (7)
• Strength Athletes: Strength athletes can increase their anaerobic capacity in HIIT sprint workouts or by doing tempo runs. 

The Winner: Although cycling offers more resistance for working your muscles, running builds more full-body strength — down to your bones. It’s a toss-up here for which type of strength you’re trying to focus on.

For Muscle Growth

If you’re aiming to gain muscle mass, you don’t head to the cardio floor as your primary form of training. But when you’re working out with an eye on getting swole, cycling and running can still help. (If nothing else, they’ll help boost your work capacity so you can handle more weight lifting. And that’ll help you bust through many shirt sleeves in the long run.)

Cycling:

• Builds Leg Muscles: Research suggests professional cyclists who ride long distances and train for years may build leg muscles from their high volume of work. However, they likely also do resistance training outside of cycling. (5)
• Older Adults and Sedentary People: Older adults and sedentary people may also build muscle through cycling. Younger adults can also achieve some muscle hypertrophy through cycling. (5)
• Some Upper Body Work: If you regularly take indoor cycling classes that engage your upper body with dumbbell work, you could theoretically build muscle there as well. Try to increase the reps over time and get enough protein to fuel muscle growth.

Running:

• More Muscle Group Engagement: Although you’ll be up against less resistance when you run, it’s a weight-bearing exercise that recruits more muscle groups. 
• May Sometimes Interfere: Concurrent training — both endurance and strength training in one cycle — may in some circumstances eat into your gains just a little bit. If you’re not eating enough to fuel all your training, or if you’re pouring most of your energy into runs instead of lifting, you may find yourself stalled in the muscle department. Make sure you’re eating enough and that you train for strength before jogging sessions to optimize your recovery and gains.

The Winner: More research suggests that you can build muscle through cycling, likely due to the higher potential for resistance and the time you can stress your muscles under tension. 

For Injury Recovery

Few things are as frustrating to a fitness enthusiast as suffering an injury and getting knocked out of your exercise routine. For some injuries, you can do cycling or running to maintain mobility, strength, and heart health. 

Cycling:

• Lower-Impact, Non-Weight-Bearing Exercise: A stationary bike comes in handy if you have an injury that allows you to use your lower body but not bear your body weight. A recumbent bike is closer to the floor and may be more accessible.
• Recovery from Running Injuries: If you’re a runner with an injury, you may find yourself cycling during recovery. You can keep your leg muscles working; just be mindful of knee pain.

[Read More: The Best Recumbent Bikes for Small Spaces, Streaming, Seniors, and More]

Running:

• Upper-Body Injury: If you prefer running and have an upper-body injury, you may be able to continue running while you recover. Of course, checking with a doctor or physical therapist is important.
• Weight-Bearing Exercise May Help Recovery: In some cases, weight-bearing exercise may benefit injury recovery better since it builds more strength than non-weight-bearing exercises. 

The Winner: Cycling, especially on a stationary bike, is a go-to for cardio exercise for most injury recovery. 

For Heart Health

Regular aerobic exercise (or cardio) is one of the best ways to protect your cardiovascular health and prevent avoidable cardiac health conditions. 

Aerobic exercise is any type of physical activity that raises your heart rate and breathing, engages multiple muscle groups, and can be performed rhythmically for some time. Aerobic activities utilize oxygen as an energy source. (8)

[Read More: The Best Budget Treadmills on the Market]

The American Heart Association (AHA) offers the following physical activity guidelines for adults. Each week, aim for: (9)

• 150 to 300 minutes of moderate-intensity aerobic exercise 
• 75 to 150 minutes of vigorous-intensity aerobic activity
• Combine the two
• Add on two days of resistance training

Reaching these minimum goals lowers your risk of cardiovascular diseases and can improve heart health by managing blood pressure and cholesterol levels. (9)