Treadmill vs. Bike: Which Offers the Best Cardio Workout?

Though they’re both a type of cardio equipment, many factors set treadmills and exercise bikes apart.

What is a treadmill?

A treadmill is a piece of equipment that allows you to walk or run indoors. It does so by feeding a short belt across the top of the device, providing a moving platform. You can manually adjust the speed.

Treadmills generally have handles on both sides of the belt platform. Some types allow you to incline the entire platform for a more challenging workout that resembles running uphill.

While most treadmills are motorized, nonmotorized options are becoming popular. Nonmotorized versions typically feature a slightly curved running surface and require you to move the belt yourself to reach the desired speed.

Research suggests that you get a harder cardio workout by running on a nonmotorized treadmill compared with keeping up with the same speed on a motorized one (1).

Both motorized and nonmotorized treadmills allow you to train the gait patterns of walking and running.

What is an exercise bike?

Exercise bikes feature a seat and pedals that mimic a cycling activity. You can find different types that target specific training goals.

For example, spin bikes resemble standard road bikes. This makes it easier for you to transfer your skills from indoor training to actual road cycling.

Meanwhile, reclining exercise bikes have a more comfortable, wider seat with the pedals positioned more forward. This places less weight on the pedals and more on the seat.

On the plus side, this reduces the impact of the exercise, making it more joint-friendly. On the downside, it also makes it harder to reach high intensities and isn’t as transferable to outdoor cycling.

Summary

Treadmills are designed for indoor running, while stationary bikes are designed for indoor cycling. Treadmills can be motorized or nonmotorized, while bikes can be designed for spinning or a more reclined position.

Treadmills’ many benefits have made them a commonplace addition to any workout space. However, there are some limitations and downsides to consider as well.

Pros of treadmills

Treadmills are an excellent way to add walking or running to your fitness program, as you won’t be limited by outdoor factors like too hot or too cold temperatures, rain, or a lack of suitable running paths or trails.

Furthermore, they let you set your speed. This can force you to maintain a certain pace to keep up, which can work as a motivating factor during your workout.

If the treadmill has an incline feature, you can add substantial challenge to your workout. Combined, the option to control both the speed and incline can make treadmill progression easier than running.

For example, while you can use a stopwatch to regulate your speed when running outdoors, a treadmill provides immediate, concrete data on your workouts. This makes workout tracking more convenient and can help you better appreciate your progress.

Although treadmills lack the views and fresh outdoor air that traditional running offers, they do allow you to set up a television or other digital experience to enhance your workout.

What’s more, research has found that treadmills increase postural control, such as balance, in older adults. This makes them a rehabilitation option, as well as a tool for aerobic exercise (2).

Cons of treadmills

Despite many benefits, treadmills have a few downsides to consider as well.

Although they mimic static surfaces, studies have shown that the gait mechanics of treadmill walking and running differ from those used on standard ground surfaces.

For example, a 2017 study among younger people recovering from ankle sprains found that walking on traditional surfaces improved ankle range of motion and lower extremity muscle strength more than walking on a treadmill (3).

What’s more, a recent study found that the running economy of elite running athletes was lower when they ran on a treadmill compared with a normal track. This means that for a given exercise intensity, the athletes ran slower on the treadmill (4).

This could mean that movement patterns trained on a treadmill aren’t as transferable to outdoor running as you might think. This is especially worth considering for competitive runners who frequently use a treadmill for training.

On the same note, one recent review found that while the biomechanics and overall movement patterns of treadmill and outdoor running are similar, the foot strike mechanics may differ more (5).

As such, if you plan to compete in nontreadmill running, you still need to routinely run on regular surfaces to train the optimal running patterns.

Another downside to keep in mind is the risk of falling off the end of the belt if you can’t keep up. Fortunately, most treadmills feature a safety leash that turns off the machine in case you get too close to the end of the platform.

A final downside is that treadmills are used indoors. As such, you miss out on the outdoor running experience that many runners enjoy.

Summary

Treadmills provide many fitness and convenience benefits. Still, they don’t perfectly mimic the movement patterns of standard running, so consider mixing up your exercise routine with outdoor runs.

Stationary bikes offer many benefits when incorporated into your fitness routine, though there are also downsides to consider.

The pros of exercise bikes

A large body of research supports using stationary bikes to improve fitness.

For example, a 2017 study in young women found that 16 weeks of spin bike training improved muscle strength, body fat, resting blood pressure, and blood sugar levels, among other health and fitness parameters (6).

Interestingly, stationary spin biking improved these metrics more than outdoor riding on normal bicycles (6).

A 2019 review similarly found that indoor cycling improved aerobic capacity, blood pressure, blood fat profiles, and body composition when used both alone or combined with other exercise and nutritional interventions (7).

What’s more, a 2014 study in older women found that stationary cycling improved overall gait and balance more than using a treadmill. However, this result is counterintuitive, and further research is needed on the topic (8).

Additionally, because treadmills impact your joints with every step, indoor cycling may be more suitable if you struggle with joint issues and require lower impact exercise.

Stationary bikes and indoor cycling offer a controlled, reliable indoor environment that isn’t affected by outdoor conditions. This allows you to exercise at night or during bad weather.

Finally, as with treadmills, stationary bike settings allow you to adjust the intensity and track your effort.

The cons of stationary bikes

A big downside of exercise bikes is that they don’t offer the benefits associated with weight-bearing exercise.

For example, weight-bearing exercises like squats, bench presses, and leg presses more effectively improve bone mineral density (BMD) than stationary cycling (9).

Loss of BMD is a symptom of osteoporosis, a chronic condition that increases your risk of fractures and similar bone injuries. It can drastically affect your health, especially as you reach older adulthood (9).

On a related note, indoor cycling doesn’t provide enough stimulus for long-term muscle building, which requires higher intensity training with weights or similar tools.

Thus, if your goal is to optimize BMD and build muscle, you should supplement your cycling with resistance and weight-bearing training.

Finally, as with treadmills, if you enjoy exercising in nature, indoor stationary biking may not be as appealing as cycling outside.

Summary

Stationary bikes offer many fitness benefits, though they’re less effective at building strong bones and muscles compared with weight-bearing exercises.

Burning calories is a major reason why many people do cardio. When comparing the calorie burn from treadmills versus stationary bikes, you have to consider the intensity and duration of your training.

Studies suggest that running on a treadmill burns 8.18–10.78 calories per minute, while stationary cycling burns 7.98–10.48 calories per minute (10).

Over a 30–60-minute session, these small differences can theoretically add up. Still, if you bump up the intensity on the bike just a little or add a few more minutes of training, you could easily be burning more calories stationary cycling than treadmill running.

For comparison, it’s worth noting that high intensity interval training (HIIT) on a hydraulic resistance system can burn a whopping 10.3–15 calories per minute (10).

This means that if time is a limiting factor, HIIT-style training will burn far more calories than steady-pace running or cycling. In perspective, this makes the calorie-burn difference between treadmills and bikes negligible for shorter workout times.

Overall, the potentially slightly higher calorie burn from a treadmill versus a stationary bike shouldn’t be your primary consideration when picking between the two.

Summary

Treadmills burn slightly more calories than stationary bikes, though the difference is negligible. For comparison, HIIT training burns far more calories per minute.

When it comes to picking the best option for you, you need to be clear on your training goals.

If you’re simply looking for the general benefits of cardio training, choosing the most enjoyable method should be your primary factor. In other words, go for the option that excites you the most.

The differences in fitness and aerobic improvements between using a treadmill or a bike are negligible. Either is a much better option than doing no exercise at all.

Meanwhile, if your goals are sport-specific, consider focusing on the primary modality of your competition.

For example, if you’re training for a 5K-run, combining outdoor and treadmill running is your best bet. On the other hand, if you’re prepping for a bike race, combining outdoor and stationary cycling is the right choice.

To improve your gait and balance, it appears that bikes may have a slight advantage over treadmills. However, more research is needed to confirm this.

If you struggle with joint issues, particularly in the ankles or knees, cycling may be the lower impact option. This is especially true during rehabilitation or physical therapy.

Regardless of which option you choose, you should consult your healthcare provider for clearance before beginning a new type of physical activity or exercise regimen.

Summary

Which option to choose depends on your goals or injuries. However, the differences are negligible in most circumstances. Ultimately, the main determinator should be personal preference and enjoyment.

Virtually all research on exercise science, fitness, and health shows that the biggest difference between exercise benefits lies between being largely sedentary versus regularly exercising.

In a nutshell, the benefits of doing regular exercise of any kind rather than being sedentary almost always outweigh any difference between specific methods of exercise. This may be especially true when it comes to aerobic training.

As such, if you’re picking between a treadmill or stationary bike, go with the option you prefer and are more likely to stick with.

If your goals are sport-specific or you have any specific injuries, you might consider choosing a bike over a treadmill or vice versa.

Overall, both treadmills and stationary bikes are excellent pieces of aerobic equipment and offer many scientifically proven benefits to your health and fitness.

Remember, it’s never too late to get started when it comes to exercise.