Fact Checked
Evidence Based Research
This article was written by one of our team of experienced writers, and fact-checked by our experts or our editors. The numbers in parentheses (e.g., 1, 2, 3, etc.) throughout the article are reference links to peer-reviewed studies.
Our team of experts includes a board-certified physician, nutritionists, dietitians, certified personal trainers, strength training experts, and exercise specialists. We are committed to providing our readers with evidence-based information that is grounded in the latest scientific research.

Curved Treadmills: Everything You Need to Know

Is a Curved Treadmill Better Than an Electronic Treadmill?

Steve Theunissen, PT
We provide honest reviews based on a thorough, multi-point testing methodology . We do earn a commission if you purchase through our links, supporting our independent product assessments. View our disclosure for more details.

If you’ve wandered through the cardio area of your local gym lately, you may have noticed a relatively new addition to the line-up. Rather than the high tech, electronically optimized gear that we’re used to seeing, this cardio trainer stands out for being decidedly low tech.

In fact, it’s not even powered by electricity. I’m talking about the curved treadmill, a pared back version of the familiar indoor running machine that is getting a big thumbs up from a lot of serious trainers.

What is a Curved Treadmill?

A curved treadmill, also called an air runner, is a non-motorized treadmill which runs off the energy of the person using it. As such it has no motor and therefore does not have to be connected to an electrical outlet. That means that this treadmill can be used either indoors or outdoors.

What Is A Curved Treadmill
Curved Treadmill

The most unique feature of the air runner, as with all treadmills in this category, is that it has a curved running bed. Conventional treadmills provide a flat running surface and are limited in terms of the ability to propel themselves forward when compared to a curved treadmill.

However, the unique curved running bed of a curved treadmill has been precision engineered to provide a far more efficient transfer of energy from your foot to the running surface, allowing you to run faster and more naturally.

The running beds on the best curved treadmills are made up of a series of overlapping rubber panels that together form an arced running surface. This increases the length of time that the foot makes contact with the surface below it.

The increased contact time results in greater energy transfer, leading to greater propulsion and more work being required by the body. The overall result of all of this is a greater level of energy expenditure as evidenced by an increased calorie burn, which adds to a more efficient workout.

The experience of running on a curved treadmill is very different to running on a standard manual or electronic treadmill. It literally feels as if you are running on air, making this a great running choice for people with ankle or other joint issues.

Curved Treadmill Pros:

  • User friendly
  • Minimal set up
  • Good for HIIT
  • Can be used anywhere
  • Natural running motion
  • Trains you to run properly

Curved Treadmill Cons:

  • No extra features that you’d expect on an electronic treadmill
  • Expensive
  • Not good for speed acceleration
  • Not good for endurance training

Curved vs Electronic Treadmill

Electronic treadmills do a decent job of helping people burn calories. Serious athletes, however, often find them to be too restrictive. The body is locked into a predefined movement pattern, pace and gait. Many people just find that they can’t simulate the real feel of running on an electronic treadmill.

The curved treadmill has been created to meet the needs of people who are looking for a more realistic indoor running experience than that offered by electronic treadmills.

Curved treadmills are engineered to bring every muscle in your lower body into play, from your glutes to your calves. The power to move the running belt comes from you, so you have total control over the speed of your workout.

Electronic Treadmill
Electronic Treadmill

And, because of the curved design of the running surface, the transfer of energy from your feet to the running platform is more efficient, natural and joint friendly than when you’re running on an electronic treadmill. With the curved surface your foot remains in contact for longer, allowing for a greater energy transfer.

The curved treadmill actually trains your body to run properly. If you are a heel striker you will find it difficult to run on the treadmill. You will quickly be forced to adjust to a ball of your foot strike.

The difference between running on a curved treadmill and an electronic one can be likened to the difference between lying on a conventional mattress and memory foam mattress topper – it feels as if you are lying, or running, on air!

When you run on a conventional treadmill, the horsepower of the motor is propelling your legs forward. You do not have that artificial help when you work out on a curved treadmill. You must do all the work yourself. As a result, you’ll burn more calories, work your muscles more intensely and produce a greater cardiovascular benefit.

Because there is no need to plug your curved treadmill into a power outlet, you can use it anywhere, both indoors and outdoors.

Another major benefit of working out on a curved treadmill is that, due to its design, it encourages you to use a correct running technique. This is very different to electronic treadmills. The artificial nature of running on an electronically propelled running surface and the pressure to keep up with the speed or match the slowness of the running belt often compromises people’s running form. You do not have these issues with a curved treadmill. Rather, the curved design of the machine encourages you to run in a natural, safe upright position.

Is the Curved Treadmill the Same as a Manual Treadmill?

Technically, the curved treadmill is a manual treadmill. However, it is light years ahead of the conventional manual treadmill market. The unique design of the curved treadmill makes it far more natural and beneficial than a conventional manual treadmill.

Manual Treadmills
Manual Treadmills

The curve at the top of the running belt provides the forward propulsion of the running belt. On a standard manual treadmill the running belt is flat. That provides zero propulsion. As a result, it is very hard to get started  and the running experience is jerky and stilted.

A really big difference between the traditional manual and the curved treadmill is the price. You can buy a manual treadmill for around a hundred dollars, while the average price for a curved treadmill is several thousand dollars.

Curved Treadmill Drawbacks

Despite the clear functional benefits of the curved treadmill, there are a couple of pretty obvious drawbacks. The first is the price. With an average price of around $5000, curved treadmills are beyond the budget of most people. It is about double the price of a high end electronic treadmill.

Another potential drawback is the relatively narrow width of the running belt. While a good electronic treadmill will provide you with a 20-22 running belt width, the standard width of a curved treadmill is just 17 inches. That may be too restrictive for larger people.

If you are used to a treadmill that includes high console functionality, you may struggle to get used to the basic functionality of a curved treadmill. It will provide you with feedback on your time, calories and distance but that’s about it.

Curved treadmills are very good for allowing you to build up to and maintain a constant speed. However, it is much harder to build acceleration. That’s because acceleration requires you to push harder with your feet while leaning forward. However, the design of the curved treadmill encourages the body to stay upright in order to maintain balance. As a result, a curved treadmill is not the best option if you are wanting to build your running speed.

Running on a curved treadmill feels quite different to running on a flat surface treadmill. Even though it is ergonomically better, it will feel strange at first, especially if you’re used to running on the electronic version. If you are not confident with your balance and coordination, you may struggle to get to grips with the challenges of getting used to running on a curved running bed.

When it comes to athletic applications, the runner will not get the vertical force oscillation that is needed to be able to develop maximum speed. The curved running bed also does not allow the sprinter to assume the proper positioning for optimal speed.

Curved Treadmill Works

Who Should Use a Curved Treadmill?

Curved treadmills are suited to both inexperienced and experienced runners. Because they force you to run in an upright manner with a front foot strike, it is an excellent running form trainer. Running on a curved treadmill will produce a higher calorie burn than on an electronic treadmill so it is a more time efficient form of cardio for people who have the goal of losing body fat.

A curved treadmill provides all runners with a more natural, close to the real thing running experience. It also provides less joint strain than you would get when running on an electronic treadmill.

High intensity athletes are going to get a better workout on a curved treadmill. Because the treadmill design keeps your form and posture on point and you get no artificial assistance, you will be working harder while more effectively working your body.

Because a workout on a curved treadmill is far more intense than one on an electronic treadmill, you will not want to use it for extended endurance type workouts. Generally, any workouts beyond 20 minutes are better suited to an electronic rather than a curved treadmill. Of course, a 20 minute curved treadmill session will produce more bang for your buck in terms of calorie burn than a 30-40 minute session on an electronic treadmill.

What are the Top Rated Curved Treadmills on the Market?

The two most popular curved treadmills on the market are the Assault Air Runner and TrueForm Air Runner. Let’s take a look at the top offering from each company.

Assault Air Runner

Assault Fitness Airrunner
Assault Fitness AirRunner

The Assault Air Runner is a user-friendly running machine. Once you hop on this air runner, it will begin to self-propel very easily. This is quite different to the other leading model in this space, the TrueForm air runner, which is designed to teach you the ideal running form. The downside is that the TrueForm is harder to get started running on.

When you want to run faster on the Air Runner, you simply move forward slightly to the front of the air runner. The curved design of the running bed gives you a very solid footing. As you are running, the running bed moves in a pendulum type motion. To go faster, you simply increase your pace.

There is very little set up required for the Air Runner. All you have to do is attach the side arms and monitor, which can be achieved by inserting a couple of bolts.

The team at Assault have designed their air runner to be able to perform high intensity interval training (HIIT) as effectively as possible. Unlike an electronic machine, which requires you to manipulate controls when doing HIIT, all you need to do on the air runner is to increase or decrease your pace. In addition, there is no maximum speed on the Assault air runner.

Quite a few who’ve reviewed the Assault have reported that an unexpected benefit of using the Assault air runner is that their posture and gait improve. Because of the curvature of the running belt, the body is trained in proper biomechanical structure when you run on it, which helps to correct postural issues.

Buy at Amazon


The Assault Air Runner is built for longevity. This is a commercial running machine which is designed for use by dozens of people every day. That means home users can have absolute certainty that it will last a lifetime.

The steel frame of the air runner is very solid and is also corrosion resistant. The slat running belt lasts for an amazing 150,000 miles.

Compact Design

The Air Runner is an impressively compact manual treadmill. In fact, it may well be the most compact treadmill you’ve ever come across. It is 70 inches long and 33 inches wide. This makes it quite a lot smaller than your conventional manual or electronic treadmill. It is also the most compact air runner that we have come across.

The weight of the Air Runner is 280 pounds. This is impressively light for a commercial piece of cardio equipment. As a comparison, the Woodway Curve Air Runner is 350 pounds.

Built-In Workouts

Despite being a manual treadmill, the Assault Air Runner does come with built-in workout programs. You get 8 programs, including a HIIT workout. Bluetooth connectivity allows you to track all of your workouts and download your data to your favorite training app.


A highlight of the Assault Air runner is its high spec console. It features inbuilt interval programs,  and target programs. It can monitor your heart rate and sync to your device. It will monitor your distance, speed, watts and pace. Your caloric output and time will also be recorded.

The monitor is very user friendly. As soon as you start moving on the treadmill, all of the diagnostics will start recording your measurements.

While the Assault allows you to go a little faster than the TrueForm, it does not provide quite as much resistance. On the TrueForm you need to self-propel more than on the assault. That is also true of the Woodway Curve Air Runner.

What’s Not So Good?

The Assault Air Runner is an expensive treadmill. It will cost you around the same amount of money as the most expensive electronic treadmills on the market. However, this is par for the course with leading air runners.

Air runners do not come with the features that you may be used to with an electronic treadmill. These include such things as incline / decline, a workout fan, music port or tablet holder. You get none of these with the Assault Air Runner.

Buy Assault Fitness AirRunner

TrueForm Air Runner Review

TrueForm Air Runner Review
TrueForm Air Runner Review

The TrueForm Air Runner Treadmill from Samsara Fitness competes with the Assault as the most popular air runner on the current market.

Samsara has three air runners on the market, each one geared toward a different target market. They are . . .

  • Low Rider – This version of the TrueForm has the smallest footprint, making it ideal for crowded cardio rooms or for home users who don’t have a lot of room to spare. It features a low handrail design that enables users to keep their balance.
  • Enduro – The Enduro has a slightly larger footprint which has a standard height handrail. This unit is primarily designed for therapy and rehab use where the runners need a great deal of rail support.
  • Performance – The Performance is the top end TrueForm unit that is especially beneficial for professional athletes who need to maximize their speed, acceleration and athletic training. The unit features a tethering system which allows the trainer to max out their explosiveness.

TrueForm Features


  • Responsive belt technology
  • Solid construction
  • Customization


  • Expensive

Smart Technology

The main point of difference between the TrueForm and the Air Runner is the smart technology that has been built into its design. As a result, most first-time users find the TrueForm harder to run on than the Assault or any of the other air runners on the market. The reason for this is that the TrueForm air runner actively trains you how to run properly. The unique curvature of the TrueForm forces the user to run with the proper toe to heel strike. When you do not run this way, you will find it quite difficult to make traction on the running bed. As a result of this, the person who uses the TrueForm will very quickly be ‘taught’ to use proper running form. In the meantime, however, they might become quite frustrated – or simply give up altogether.

If you are a person who is not interested in being trained in proper running technique then you will probably be better off with the Assault than the TrueForm air runner.

The curvature of the TrueForm bed is designed to force the user to run with the proper toe to heel foot strike.

If you don’t, you’ll have great difficulty gaining any traction. The curved bed also helps to prevent such bad running habits as looking down, over-striding and not keeping your hamstrings and glutes tight. This will soon train the user to use the proper running form.

TrueForm calls their form adjustment technology RBT or Responsive Belt Technology. In addition to training you to be an efficient runner, it will also allow you to get fitter faster. According to the TrueForm website, you will burn 44 percent more calories when you run on the TrueForm compared to other treadmills.

Build Quality

Like the Assault air runner, the TrueForm is a commercial treadmill. That means that it is built to last a lifetime, especially in a home gym setting. The specifications on this machine are very high spec.

The running belt will provide you with more than 200,000 miles of use. The drive system provides you with 106 Precision stainless steel sealed bearings & 14 precision machined, solid aluminum guide rollers.

All of the metals used in the construction of the TrueForm are high grade, hand-crafted and welded in the United States. The tread surface of the TrueForm air runner is formed from vulcanized rubber manufactured exclusively for TrueForm by Smith and Wesson while the frame is made from heavy duty 7-gauge solid steel construction, hand formed & welded.

Custom Thread

There are several customized features of the TrueForm that set it apart from the opposition, including the Assault Air Runner. A very unique feature is that it gives you the option of customizing your running bed. The default bed is made of black rubber. However, you also have the option of having your air runner arrive with any of these running beds:

  • Artificial Turf
  • Running Trail
  • Track Surface
  • Wood

This option of choosing your own running surface is perfect for competitive athletes and sports people as it allows them to warm up with their cleats or spikes on and then go directly into the competition or game with cooling down.

Color Options

The standard color for the TrueForm is a classic black powder coat. However, for an additional $275, you can have your air runner custom painted in an array of color options.

Optional Digital Display

You can purchase an optional digital display for your TrueForm which will give you a readout of your pace (in minutes per mile), speed in miles per hour, and distance and time. In contrast to this, the Assault Air Runner provides you with a comprehensive monitor as standard.

Minimal Assembly

Just like the Assault Air Runner, the TrueForm is ready to use out of the box. If you wish to fit the handrails it may take a few extra minutes to do so, requiring the screwing in of just a couple of bolts.


The TrueForm is a little bigger and heavier than the Assault air runner. However, the built-in transportation wheels make it easy to move around your training facility. It also comes with handles at the front of the unit to make it even easier to handle.

Buy at Amazon


A curved treadmill will provide you with the most natural indoor running experience that currently exists. It will also train you to use proper running form, burn a whole lot more calories and produce a far more intense workout than an electronic treadmill.

While it is not designed for speed acceleration training or endurance workouts, it is an excellent cardio option for high Intensity Interval Training. While you may not have the budget or the inclination to purchase a curved treadmill for your home, incorporating it into your gym training program makes a lot of sense. 

Why not give it a try during your next gym visit?

If you have any questions or need further clarification about this review, please leave a comment below, and Steve will get back to you as soon as possible.

Stay on top of the latest fitness news and updates by adding Fitness Volt to your Google News feed: Follow us on Google News You can also follow us on Twitter, Facebook, Instagram, and YouTube for even more content.
Steve Theunissen, PT
Steve Theunissen, PT
Steve Theunissen is a former gym owner and personal trainer and is the author of six hardcopy books and more than a hundred ebooks on the topics of bodybuilding, fitness and fat loss. Steve also writes history books with a focus on the history of warfare. He is married and has two daughters. Steve hold the following certifications from the International Sports Sciences Association: * Certified Personal Trainer * Fitness Nutrition Certification * Specialist in Group Fitness & Guided Study * Strength & Conditioning Certification * Sports Nutrition Certification * Transformation Specialist & Guided Study

Leave a Reply

Your email address will not be published. Required fields are marked *