The Best Treadmills with iFIT of 2024

If you’ve found yourself in a rut with training, online workout programs can be a great tool to keep your sessions fresh. One such service is iFit, boasting over 17,000 live and on-demand fitness classes. The program is so popular that it’s been integrated into many top-performing cardio machines, including treadmills. The best treadmills with iFit take full advantage of the online fitness platform, giving your daily walks and runs a fresh face to keep you active, entertained, and above all else, progressing forward.

iFit is available on treadmills from top brands such as NordicTrack, ProForm, Freemotion, and Matrix. With several different brands to choose from, it can be difficult to decide which profile is right for your space. So, to get you off and running in your search, we tested 14 iFit-enabled machines, paced through mounds of research, and consulted with customer reviews to curate this round-up of our favorite treadmills with iFit.

The 6 Best Treadmills with iFIT of 2024

• Best Treadmill with iFIT Overall: NordicTrack Commercial 1750
• Best Treadmill with iFIT for Running: ProForm Pro 2000
• Best Budget Treadmill with iFIT: NordicTrack EXP 7i
• Best Treadmill with iFIT for Walking: ProForm City L6
• Best Incline Treadmill with iFIT: NordicTrack Commercial X32i
• Best Premium Treadmill with iFIT: ProForm Pro 9000

How We Tested the Best Treadmills With iFIT

The BarBend team is made up of competitive athletes, certified personal trainers, and lifelong fitness enthusiasts. We’ve gotten hands on (err, feet on) with a variety of treadmills over the years, so we understand which profiles are worth their weight when it comes to home gym equipment. Additionally, we’ve trained with a number of online workout programs, and have spent a fair amount of time with the iFit platform.

For this round-up, we limited our test subjects to iFit-enabled treadmills, comparing our experiences with these machines to our trials with other premium treadmills over the years. We examined common factors that go into treadmill purchases, including how big the machines are, how adjustable they were in terms of speed and incline, and whether or not they could be stored easily when not in use.

We also looked for treadmills with worthwhile displays offering clear, crisp visuals for integrated training. The iFit platform is a visual experience, after all, so it helps to have a device that can actually showcase the live and on-demand workouts without much strain.

Finally, treadmills are some of the most expensive home gym machines out there, so we looked for profiles at a wide range of prices to cater to different budgets. An iFit subscription remains constant at $39 per month, regardless of your device, so we focused more on the device’s price tag for this round-up. 

Best Treadmill with iFIT Overall: NordicTrack Commercial 1750

Specs

• Price: $2,499.99
• Max Incline and Decline: 12% incline, -3% decline
• Max Speed: 12mph
• Weight Capacity: 300lbs
• Product Dimensions: 80” L x 38” W x 65” H
• Display Size: 14”

Pros

• This treadmill supports incline and decline training at pitches between negative three and 12 percent.
• The 14-inch HD touchscreen pivots for off-treadmill workouts.
• Our tester praised this treadmill’s sturdiness, even when training at high intensities.

Cons

• The large 21.11 square footage footprint may not be ideal for smaller spaces.
• This heavy treadmill can be difficult to move around your space.
• Keeping this treadmill in the garage can void the warranty.

The NordicTrack Commercial 1750 is one of our favorite treadmills in general, so it makes sense that it tops our list of iFit-enabled machines, too. This impressive profile can reach speeds up to 12 miles per hour, boasts a worthwhile incline range between negative three and 12 percent, and comes equipped with a Runners Flex cushioned running deck for added comfort in training.

Our tester also noted how seamless the integrated AutoAdjust technology was during trials. This feature works in tandem with the iFit platform to control your speed and incline adjustments with your online fitness classes. For example, when our tester encountered a rolling hill along their digital running route, they enjoyed how the deck actually mimicked the on-screen course.

We also had no issues with the treadmill’s sturdiness, even when training at high intensities. Other, less stable treadmills can wobble and jostle when you ramp up the pace and open your running gait for stronger, faster strides, but the 1750 was solid even at top speed. This is a logical perk to this machine, after all — it weighs over 300 pounds.

Additionally, the Commercial 1750 features a 14-inch HD touchscreen that provides clear visuals throughout your workout. This display can also tilt and pivot, which is great for following along with iFit’s off-treadmill workouts.

On a final note, the Commercial 1750 is a large machine, taking up 21.11 square feet of space during operation. The deck does have a hydraulic folding mechanism for easier storage, but it’s still a hefty footprint, nonetheless. If you’re living in confined spaces, it may be best to look for a smaller profile.

Read our full NordicTrack Commercial 1750 Review.

Best Treadmill with iFIT for Running: ProForm Pro 2000

Specs

• Price: $1,799
• Max Incline and Decline: 12% incline, -3% decline
• Max Speed: 12mph
• Weight Capacity: 300lbs
• Product Dimensions: 77.3” L x 35.3” W x 59.6” H
• Display Size: 10”

Pros

• The 20-inch by 60-inch running deck is spacious enough for most running gaits.
• The max speed and incline settings can be suitable for higher-intensity running sessions.
• The included pulse sensors and heart rate monitor are useful for tracking your metrics during workouts.

Cons

• The smaller 1.9-inch rollers will require the motor to work harder for worthwhile belt revolutions.
• The 10-inch display does not swivel or rotate for easier off-treadmill training.
• The $1,799 price tag may not be ideal for athletes on a tighter budget.

When you increase your running speed, you increase your stride length and frequency. (1) As such, having a treadmill that can support your gait are you put in the miles is ideal. Thanks to its expansive 20-inch by 60-inch running deck, the ProForm Pro 2000 is plenty capable of keeping up with your higher-intensity running workouts.

We also appreciate how this treadmill can reach speeds up to 12 miles per hour, inclines up to 12 percent, and declines down to negative three percent. This adjustability can be ideal for switching up your running routes as you follow along to one of iFit’s thousands of available fitness classes. The 10-inch display is also great for such situations, although it’s less ideal for off-treadmill workouts. This display module doesn’t swivel or pivot for easier viewing in off-treadmill workouts, so you’ll have to use a smartphone or tablet.

The ProForm Pro 2000 is also a favorite of ours for running thanks to the included pulse sensors and chest strap heart rate monitor. These tech-heavy features can help you track your data for a more well-rounded analysis of your performance throughout training. Plus, the Bluetooth compatibility allows you to stream your metrics right to the display, so all your data is upfront and readable as you pace through your circuits.

The one area we recommend paying attention to, though, is the roller size. The 1.9-inch rollers are on the smaller side when it comes to treadmills, which can impact your machine’s working capabilities over time. Smaller rollers will require the motor to work harder to achieve quality belt revolutions. That extra wear and tear, in turn, can lead to quicker burnout across the motor and rollers with extended use. Thankfully, ProForm covers the Pro 2000 with a hearty warranty package including 10-year support for the frame, two-year coverage for parts, and one-year coverage for labor. 

Read our full ProForm Pro 2000 Review.

Best Budget Treadmill with iFIT: NordicTrack EXP 7i

Specs

• Price: $1,299
• Max Incline and Decline: 12% incline, 0% decline
• Max Speed: 10mph
• Weight Capacity: 300lbs
• Product Dimensions: 70.8” L x 34.9” W x 59.7” H
• Display Size: 7”

Pros

• The $1,299 price tag is more affordable than other treadmills in this round-up.
• The EXP 7i’s seven-inch touchscreen is a rare feature for treadmills at this price range.
• The foldable deck and wheeled front make moving and storage simple endeavors.

Cons

• The 55-inch running deck may be too short for athletes with longer strides.
• Athletes wanting a larger display should look elsewhere.
• The smaller 1.9-inch rollers can lead to more wear and tear on the motor during extended use.

If you’re already planning on subscribing to iFit for $39 per month, odds are you’d like to keep your treadmill machine costs as low as possible. The NordicTrack EXP 7i is our favorite budget-friendly iFit treadmill, coming in at just under $1,300. 

This may seem like a higher price tag for a wallet-friendly profile, but if you consider the fact that this treadmill can reach speeds up to 10 miles per hour, supports inclines up to 12 percent, and boasts an actual touchscreen display, the numbers start to make sense, and the deal becomes more apparent.

In testing, we appreciated the OneTouch controls that allowed us to quickly adjust our speed and incline with a single touch of the button instead of continuously toggling these metrics to our desired levels. Additionally, our tester noted that the seven-inch touchscreen is easy to read, providing all their metrics and readouts as they paced through their iFit workouts. It’s not the largest display in this round-up, but it’s a welcome benefit, especially for a treadmill at this price range.

The EXP 7i can also be a worthwhile investment for athletes living in smaller spaces. When in use, the treadmill takes up just 17.16 square feet of flooring. Additionally, SpaceSaver technology allows the running deck to fold up for storage, so you can get some space back when not in the throes of training.

As performance-laden as the EXP 7i is, though, we don’t believe it’s a sustainable option for high-intensity training. For one, the running deck is shorter than other treadmills at just 55 inches. This could be too short of a running plane for athletes with longer strides, or those wanting to take part in all-out sprints. Additionally, the 1.9-inch rollers will require some extra effort from the 2.6 CHP motor to achieve proper belt revolutions during workouts. This extra output could lead to more wear and tear across these components over time.

Read our full NordicTrack EXP 7i Review.

Best Treadmill with iFIT for Walking: ProForm City L6

Specs

• Price: $599
• Max Incline and Decline: N/A
• Max Speed: 8mph
• Weight Capacity: 250lbs
• Product Dimensions: 70.25” L x 29” W x 44.5” H
• Display Size: N/A

Pros

• The City L6’s 1.6 HP motor is powerful enough for extended walking and light jogging.
• The sub-$600 price tag can be great for athletes on a budget.
• The City L6 folds neatly onto itself for convenient storage under furniture.

Cons

• A separate smartphone or tablet is required to follow along with iFit fitness classes.
• This treadmill is not powerful enough to support higher-intensity running sessions.
• There are no incline or decline settings for more varied training setups.

Training with an iFit-enabled treadmill doesn’t always need to entail running or jogging. Walking can also be a worthwhile endeavor for improved cardiovascular health. (2) For these slow-rolling workouts, we recommend the ProForm City L6 treadmill.

While this profile isn’t powerful or large enough to support your all-out sprints, the eight mile-per-hour max speed and 17.5-inch by 45-inch tread belt can be suitable enough for walking purposes. Plus, when you connect your personal smartphone or tablet via Bluetooth to the City L6, you’re able to follow along with iFit walking sessions that automatically adjust your speed in tandem with your instructor.

We appreciate the simplicity of this machine, most notably in the folding makeup of the profile. Our tester enjoyed how compact the City L6 was when not in use, and the folded silhouette (roughly 11.5 inches tall) was slim enough to store easily under a nearby bed or couch. Additionally, the digital display was great for tracking time, distance, and calories as they strolled through their daily step count.

Finally, athletes on a budget will appreciate the $599 price tag. This can be an effective way to take advantage of your iFit membership without sacrificing your floor plan for a larger, more expensive machine. You don’t get all the bells and whistles like incline adjustments or a built-in display, but you can still produce worthwhile results with this walking-ready silhouette from ProForm.

Read our full ProForm City L6 Review.

Best Incline Treadmill with iFIT: NordicTrack Commercial X32i

Specs

• Price: $4,499
• Max Incline and Decline: 40% incline, -6% decline
• Max Speed: 12mph
• Weight Capacity: 300lbs
• Product Dimensions: 76.5” L x 40” W x 73” H
• Display Size: 32”

Pros

• This treadmill can reach an incline of 40 percent.
• The large 32-inch display provides clear, easy-to-follow visuals through the iFit platform.
• The 22-inch by 65-inch running deck provides ample space for all-out sprints.

Cons

• Our tester notes that assembly requires two people given the machine’s massive size and weight.
• At nearly $4,500, this is one of the most expensive iFit treadmills available.
• The Commercial X32i cannot fold up for more convenient storage.

Incline training can be an excellent way to boost your running economy. (3) While many of our favorite treadmills with iFit support such settings, there are few that match the pitch capabilities of the NordicTrack Commercial X32i. This behemoth of a machine can reach inclines up to 40 percent, along with declines down to negative six percent, giving you plenty of room to vary up your approach angles during sessions.

In testing, we also appreciated how stable the Commercial X32i was, even when training at high intensities. According to our tester, the only indication that they were running at the max 12 miles per hour was a slight jostle across the massive 32-inch screen. There was no feedback or shaking across the well-cushioned 22-inch by 65-inch running deck, creating a firm yet cozy surface for max output time and time again.

That stability is good for pushing yourself to your absolute limit, but moving the treadmill itself can be quite the challenge. With a footprint of 21.25 square feet, you’ll need ample space to house this iFit treadmill. It should also be noted that the Commercial X32i does feature any folding components, meaning you can’t regain floor space when not using the device.

We also recommend getting a helping hand for the assembly process. In total, this treadmill weighs nearly 460 pounds, and the components aren’t easily handled just by yourself. So, it’s best to have an associate assist with the installation before you set your sights on new training heights.

Read our full NordicTrack Commercial X32i Review.

Best Premium Treadmill with iFIT: ProForm Pro 9000

Specs

• Price: $2,299
• Max Incline and Decline: 12% incline, -3% decline
• Max Speed: 12mph
• Weight Capacity: 300lbs
• Product Dimensions: 77.3” L x 35.3” W x 59.6” H
• Display Size: 22”

Pros

• This treadmill has a lot of convenient amenities, including a SpaceSaver design, CoolAire fan, and Bluetooth audio capabilities.
• The 3.6 CHP motor is powerful enough for extended high-intensity training.
• ReBound Pro cushioning across the deck can be ideal for soft landings and in-training comfort.

Cons

• Our tester noted connectivity issues between the treadmill and their WiFi network.
• There’s no dedicated water bottle across the console, just open storage compartments.
• There are more budget-conscious options available for athletes looking to save some money.

For athletes wanting a luxe training experience, the ProForm Pro 9000 should definitely be on your radar. Boasting a wide 22-inch HD touchscreen, powerful 3.6 CHP motor, and well-cushioned running deck supported by ReBound Pro technology, this treadmill has all the bells and whistles to make every workout an enjoyable experience.

Our tester enjoyed their trials atop this feature-rich profile, highlighting the Quick Speed Controls which were great for interval training. The one-touch toggles allowed them to seamlessly change speeds and inclines across the machine, rather than hitting the arrowed dials constantly to reach their desired metrics.

The Pro 9000 also boasts automatic adjustments for athletes following along to iFit fitness classes. Instead of pausing your workouts to adjust your speed and pitch, the machine automatically changes these metrics for you when your session calls for alterations. This can be great for keeping focus mid-training, eliminating any burdens that come with achieving a proper setup.

We also liked how cushioned and comfortable the 20-inch by 60-inch running deck was during exercise. The ReBound Pro absorbed a good bit of the impact experienced during strides, which can be ideal for athletes dealing with joint discomfort.

The one thing of note, though, when setting up this iFit-enabled treadmill is to position it as close to your WiFi router as possible. Our tester experienced some connectivity issues during their initial setup, so it’s best to give your machine a clear pathway for a secure connection. From there, taking advantage of iFit’s over 17,000 online classes and challenges is just a few steps away.

Read our full ProForm Pro 9000 Review.

How We Chose the Best Treadmills With iFIT

Finding a treadmill with iFit integration is a little more simplified than finding a treadmill in general. After all, you’re limiting the playing field by first confirming the machine supports the iFit platform, right? Still, we looked at a handful of other components to ensure our round-up delivered the best of the best.

Equipment Footprint

Treadmills are by no means compact pieces of fitness equipment. Even the slimmest, most storage-capable silhouettes take up some space while in operation. To cater to all training spaces and living arrangements, we looked at a number of treadmills showcasing varying footprints from 14 to 22 square feet.

We included the overall product dimensions above, and pointed out when treadmills showcased any folding features to aid in convenient storage. If a treadmill didn’t showcase any storage-friendly features, we made sure to recommend them for athletes with larger spacial availability.

Speed and Incline Settings

Having multiple speed and incline settings at your disposal can help you create a varied training setup day in and day out. When you account for iFit integration, these settings can allow you to take full advantage of the service, most notably through the platform’s AutoAdjust feature showcased in a handful of treadmills.

We looked for a variety of speed and incline ranges when curating this guide, pointing out where the ranges could be best utilized in certain training scenarios. If a treadmill wasn’t able to accommodate high-intensity running, which related to its max speed, we made note of it and provided recommendations for how to best utilize the machine for light jogging or walking.

In general, we searched for treadmills capable of speeds between eight and 15 miles per hour, along with inclines of at least 12 percent. We found these to be worthwhile metrics that could support a variety of training needs.

Display Size

If you’re looking to follow along with iFit’s library of training classes, it helps to have a treadmill capable of streaming the programs in a worthwhile manner. When creating this guide, we searched for treadmills offering quality display modules at varying sizes from 7 to 32 inches. We made note of how clear and detailed the pictures were during trials, as well as whether the displays were adjustable to better facilitate off-treadmill training sessions.

If a treadmill didn’t showcase an integrated display, it definitely dropped in our rankings, but wasn’t completely out of the running. For these scenarios, we made sure that the consoles featured a media holder so you could rest your smartphone or tablet in front of you for a sort of DIY display setup.

Price

When looking for a treadmill with iFit, you’re already agreeing to invest $39 monthly into your fitness journey. So, to help ensure your budget isn’t stretched too thin, we looked at treadmills showcasing a variety of prices. We tested budget-conscious silhouettes and luxury-riddled profiles, finding that most fell between $600 and $2,500. Outliers are, naturally, available in the space, but this was the range we found more often than not.

The Benefits of Treadmills with iFIT

Studies show that regularly exercising on a treadmill can be a great way to improve your cardiovascular health and general quality of life. (4) As positive as this training discipline can be, though, the repetitive nature of running on a treadmill can leave some less enthused to take part in the activity day after day. 

Integrating the iFit online workout platform to your training schedule can be a unique way to keep your fitness goals intact while bringing a refreshing sense of engagement to your exercise routine. “iFIT programming is some of the best interactive fitness programming available, especially for cardio,” says Amanda Capritto, certified personal trainer. “You can take exercise classes much like you would in a brick-and-mortar fitness studio.”

Below are a few benefits that can come with adding an iFit-enabled treadmill to your training space.

Training Variety

It can be good to mix things up every now and again with your workouts, and there’s no shortage of opportunities with the iFit platform. The library boasts over 17,000 available fitness classes and sessions, giving you plenty of chances to refresh your running pace and routes. 

Additionally, many of the top-performing treadmills with iFit utilize automatic adjustments, meaning the changes to your speed and incline during training are controlled by your chosen workout. You don’t need to worry about pausing your sessions to match your settings to your instructor — just continue to run or walk and the machine adjusts accordingly.

On- and Off-Treadmill Workouts

The iFit platform also has dedicated workouts for HIIT, yoga, bodyweight training, and other disciplines, which can be viewed and streamed through your treadmill’s on-unit display. This can be a great perk to have in your back pocket when running or walking isn’t as enticing of a workout for a given day.

Some iFit treadmills even allow for more convenient off-treadmill viewing with adjustable displays. These pivoting consoles can allow you to set up adjacent to your machine while still keeping your instructor or fitness class within view.

Data Tracking

Another benefit to running on a treadmill with iFit is the data-tracking capabilities of the platform. Each completed session gets logged with your account, creating a resource to showcase your average metrics like distance traveled, average speed, and calories burned in a given workout. This can also serve as a source for motivation, giving you a roadmap of where you began and how much progress you’ve made throughout your journey.

How Much Does iFIT Cost?

When looking for a treadmill with iFit, you’re likely interested in the online workout program itself. Still, though, this service full of training potential is an added cost in addition to your treadmill itself. So, how much does an iFit subscription really cost?

According to the brand, iFit is a subscription-based service listed for $39 per month. A membership grants you access to over 17,000 fitness classes and sessions led by qualified fitness experts. This equates to roughly $468 per year, so if you’re purchasing a $2,000 iFit-enabled treadmill, you need to ensure your budget will support the actual $2,468 price tag.

If you’re more invested in long-term training with iFit, you can potentially save some coin by opting for yearly memberships. These plans may cost more upfront, but are cheaper than paying month-to-month. Currently, iFit offers one-year memberships for $396 ($72 in savings), two-year memberships for $699 ($237 in savings), and three-year memberships for $899 ($505 in savings).

Now, you don’t need to make a decision at the start. Most treadmills with iFit come equipped with a 30-day trial period that can be great for learning the platform and testing whether it fits your training needs. At the end of this trial run, though, it can be helpful to be prepared for the $39 monthly charge.

How to Choose the Best Treadmill with iFIT

Choosing the right treadmill with iFit integration can be a tricky endeavor if you’re not sure of what to look for. Outside of the (obvious) iFit integration, you also want to be certain that the following factors are aligned with your fitness wants and needs.

Determine Your Available Space

Treadmills are some of the largest pieces of cardio equipment you can purchase for your home, with some profiles taking up more than 20 square feet of space during operation. Be sure to look at the overall product dimensions when searching for a worthwhile iFit treadmill. 

These metrics can provide you with a solid estimate of how much space you’ll need to house the machine during training. It can even be wise to leave a few feet of space surrounding your treadmill, if possible, to make it easier to hop on and off the machine.

It can also be helpful to look for treadmills featuring some form of storage-friendly folding mechanism. These features can allow you to fold the running deck upright while the treadmill isn’t being used. You’ll still need to accommodate the listed product dimensions, but being able to fold the treadmill upright can help your space maintain that homely vibe without resembling a full-blown training center.

Think About Your Training Intensity

How hard you work out can greatly influence how powerful your treadmill should be. If you want to perform all-out sprints day in and day out, make sure to look for an iFit treadmill boasting max speeds of at least 12 miles per hour. You should also look for profiles with a larger running deck, roughly 20 inches by 60 inches. These dimensions can better accommodate the longer stride lengths you’ll exhibit at running paces. (1)

If you’re looking to walk or lightly jog throughout your iFit-enabled workout regimen, you can opt for a less powerful machine with a shorter running surface. It may be best to opt for a more capable machine from the start, however, in case you want to push your training further in the future.

Ensure Your Display is Large Enough

One of the main benefits of having a treadmill with iFit is the ability to stream and follow along with the platform’s large library of on-demand fitness classes. That perk goes right out the window, though, if you can’t actually see the streaming sessions, or, at least, view them comfortably across a large enough display. 

When searching for the best treadmill with iFit for your needs, take a good look at the listed display measurements, as this can dictate how easy it is to follow along to your instructors, challenges, and running routes. We recommend searching for a screen that’s larger than your smartphone yet smaller than your home TV — somewhere between seven and 32 inches.

If your chosen treadmill doesn’t feature an integrated display, make sure it at least boasts a convenient media shelf so you can connect your smartphone or tablet for an optimal viewing experience.

Set Your Budget

Along with your iFit subscription, you’ll need to ensure that your treadmill fits within your means. Most of the top-performing treadmills will fall between $600 and $2,500, with some costing as much as $4,500. 

More expensive treadmills typically come equipped with more powerful motors, larger displays, and more-cushioned running decks, but there’s still plenty of training potential baked into cheaper options, too, especially when you consider that these machines already come with the benefit of iFit integration. In the end, the best profile is the one that leaves you with a comfortable sensation post-purchase … and a feeling of accomplishment post-workout.

Final Word

Having a treadmill with iFit can be excellent for keeping workouts engaging, progressive, and fun. The best iFit treadmills make the most of the integration with performance-laden builds, worthwhile displays, and versatile settings to help you get the most out of your daily miles.

Finding the right iFit treadmill for your needs is similar to that of searching for a worthwhile treadmill in general. You need to ensure the profile itself fits your space and budget while also confirming that the speed and incline settings are capable of supporting your training intensity. Additionally, you need to factor in the monthly subscription costs of iFit. Thinking through these factors, and using this detailed guide as a roadmap, can have you crushing your daily workouts in no time.

Treadmills With iFIT FAQs

References

1. van Oeveren, B. T., de Ruiter, C. J., Beek, P. J., & van Dieën, J. H. (2017). Optimal stride frequencies in running at different speeds. PLOS ONE, 12(10).
2. Murtagh, E. M., Murphy, M. H., & Boone-Heinonen, J. (2011). Walking: The first steps in cardiovascular disease prevention. Current Opinion in Cardiology, 25(5), 490–496.
3. Ferley, D. D., Osborn, R. W., & Vukovich, M. D. (2014). The effects of incline and level-grade high-intensity interval treadmill training on running economy and muscle power in well-trained distance runners. Journal of Strength and Conditioning Research, 28(5), 1298–1309.
4. Chan, L., Chin, L. M. K., Kennedy, M., Woolstenhulme, J. G., Nathan, S. D., Weinstein, A. A., Connors, G., Weir, N. A., Drinkard, B., Lamberti, J., & Keyser, R. E. (2013). Benefits of intensive treadmill exercise training on cardiorespiratory function and quality of life in patients with pulmonary hypertension. Chest, 143(2), 333–343.