You may notice that the speed from your Stryd device differs from the speed on your treadmill display. This is normal.
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To explain why this is, it is important to understand there are three speeds/paces you could look at while running on the treadmill.
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​The first speed is the speed displayed on the treadmill console.
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This speed represents the speed at which the treadmill is trying to run the belt. However, due to the degradation of the treadmill motor/poor control over the motor, this speed is not the same speed that the belt is running at.
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The treadmill is not a constant pace machine. It is not an accurate pace machine. It is not a consistent pace machine. A treadmill only spins a belt and that belt speed can change in a run, between runs, and run at any speed it wants to run at, independently of what the treadmill display may say.
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​The second speed is the actual speed of the treadmill belt.
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​This speed is much closer to the speed that the runner is running at, however, the treadmill belt speed is still not the same as the speed of the runner.
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As we covered back in 2017 (https://blog.stryd.com/2017/02/10/mysteriously-low-treadmill-pace-2/), the treadmill's belt speed isn't actually constant. More specifically, when your foot strikes the belt, the motor is loaded and the belt slows temporarily. Conversely, when your body is in the air, the motor applies an extra speed to the belt to recover from the previous loading. This extra speed is recorded by the treadmill, but it isn't applied to you as the runner.
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​The third speed is the actual running speed.
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This can only be captured by a foot pod. A Stryd power meter is one of the best ways to track this because a Stryd pod is fundamentally a motion capture device. It knows the displacement from one stride to the next and, from that info, the speed you are running at on the treadmill.
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​The reported pace and distance from your Stryd pod will be a far better representation of your true running speed.
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The topic of "true running speed" vs "treadmill speed" has been covered by top leaders, such as Fellrnr and DCRainmaker, in the fitness technology space.

Please see Fellrnr's explanation of this topic here: http://fellrnr.com/wiki/Stryd#Treadmill_Problems

Please see DCRainmaker's explanation of this topic here: https://www.dcrainmaker.com/2019/01/treadtracker-treadmill-accuracy.html#accuracy-testing
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​Why is the correct indoor pace important for runners?
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The Stryd power meter bridges the gap between indoor and outdoor running for the first time. You can directly compare your running intensity from outdoors and bring it indoors to create a seamless training plan. This knowledge helps improve run training because runners can consistently improve and measure their performance year-round.
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​Why does it feel harder to run on the treadmill?
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While running at the same pace, running indoors can feel more difficult compared to outdoor running.
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- Heat builds up around the body quickly because there is less airflow indoors
- Some runners are not well adapted to running on the indoor surface compared to the outdoor running surface, which can increase the RPE of the runner
- The treadmill surface is jerky. The treadmill belt is constantly slowing down and then speeding back up which will cause your body to engage extra muscles.
- Inadequate lubrication between the treadmill belt and rollers. You may need to apply new or more lubrication to the rollers, which will make your treadmill run smoother.
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​Why should you use power on the treadmill instead of pace?
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As you can tell, it is hard to dial in at an exact pace while running on the treadmill. You should treat the speed dial on the treadmill as an intensity selector. If you are not reaching the proper power target, you should increase the intensity on the treadmill. If you are too high, you should dial down the intensity.
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​Should I calibrate my Stryd pod?
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​It depends on what you would like.
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1. TRUST YOUR STRYD DEVICE:
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​The accuracy of a Stryd pod out of the box exceeds all other wearable devices such as GPS watches and other foot pods.
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Most Stryders choose to trust the values from the Stryd pod due to the difficulty of completing a controlled precision test i.e. You would not want to compare a ruler (a Stryd power meter) against a less accurate ruler (an unmeasured track, a race result, or GPS), therefore you are better off trusting Stryd.
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2. VERIFY OUTSIDE:
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​Your Stryd power meter will maintain the same accuracy from outdoor running when you move indoors to the treadmill. You can verify the accuracy of your Stryd pod by running outside and performing a controlled accuracy test on the track. You can find instructions for that here: https://support.stryd.com/hc/en-us/articles/115004337834-Distance-and-Calibration
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​3. PERSONAL PREFERENCE:
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If you would prefer the speed/distance from your Stryd pod to match the speed/distance that is being displayed on your treadmill, you can adjust the calibration factor on your sports watch to scale your Stryd pod's pace and distance to match the pace value on the treadmill's display. Be sure to adjust your calibration factor before you run again outside, or you will receive inflated pace values when running outdoors as well.
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NOTE: This choice will nearly certainly make your Stryd pod less accurate on the treadmill. You are purely choosing to do this out of preference.
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​​4. VERIFY INSIDE:
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We recommend verifying the accuracy of your Stryd power meter outdoors on a measured track but you can also perform a treadmill test. However, this is a fairly difficult process so an outdoor test is generally preferable. You can find instructions for a treadmill pace/distance verification test here: http://fellrnr.com/wiki/Treadmill_Calibration

Treadmill running is an inherently different strain on the human body than outdoor running. Being confined to a small belt that is moving below you and in a stationary location alters the effort and efficiency in a few ways that can make a treadmill run feel easier or harder than comparable power on an outdoor run. These changes in sensation do not indicate that the Stryd foot pod is malfunctioning or reporting incorrectly. Instead, treadmill workouts should be built differently from outdoor runs. Below are a couple of things that might contribute to a change in perceived effort for a treadmill run and how to adjust your indoor workouts to account for these factors. If more than one applies, the effects of each one are not additive (do not decrease your power targets by 2x if gait changes and heart rate both seem applicable).

NOTE: Stryd offers a collection of Treadmill Workouts standard with the Stryd Mobile App. These workouts were made with the treadmill in mind, and won't need modification under the effects described below.

Gait changes

Running on a treadmill belt changes your running mechanics. The treadmill belt limits where you can step and it is moving below you, and it also simulates much more constant running conditions that you experience on an outdoor run. Recent studies have shown that there are substantial changes to the way humans run on a treadmill with comparison to outdoors. The changes the treadmill creates in your natural stride can make it feel like you are running at a higher power than you are. If you notice this trend, reduce the power target for treadmill workouts so your perceived effort is similar to what it would be outside.

Heart rate

Runners will sometimes note that their heart rate is higher for a treadmill run than an outdoor run even when their running power is the same. When running in a stationary location, it is common for heat to build up around the body versus be lost to the environment as it is in an outdoor run. The decreased ability for the body to cool itself can increase your heart rate at the same power output.

It is also worth noting that heart rate is a poor metrics for work in general. It fluctuates from day to day and is affected by factors beyond running strain. It is often inconsistent and can vary even without the heating effects described here.

For the purposes of keeping the effort feeling the way you think it should, decrease your power targets for treadmill workouts compared to what they would be for an outdoor run.

Ventilation and air flow

Ventilation and airflow are limited in treadmill running with comparison to outdoor running. This can lead to the same heating effects described under Heart Rate above, but can increase perceived effort at a given power number without increasing heart rate. If your efforts is higher due to stagnant air or overheating, reduce your power targets for treadmill workouts with respect to the outdoor workout equivalent.

Mental fatigue

Treadmills are stationary. It is difficult for them to provide the same kind of mental distraction and engagement with your surroundings that you will get running outside. The reduced distraction can cause a runner to become more focused and aware of their effort, and can consequently feel they are working harder at the same power number.

Mental distraction and fatigue has little impact on the work of your body. Any change in RPE associated with mental fatigue does not require a change in power targets for your treadmill workouts, but you may choose to lower power targets if you believe it may help improve the run experience.

Airpower

There is no air power contribution when a runner is stationary as they are on a treadmill. It is normal for air power to contribute 0-10 watts to an outdoor run, but there is no air power in treadmill workouts. This means the pace or incline must be adjusted to reach a similar power target.
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You might notice that your power fluctuates while running on a treadmill, even though the pace is very constant. The spikes in power are caused by changes in air pressure while you are running on the treadmill. Pressure changes are interpreted by Stryd as changes in elevation, causing power to fluctuate.

You can avoid these fluctuations if you record your run with the Stryd app on your phone in the indoor mode or the indoor mode on either the Stryd Apple Watch app or the Garmin Stryd Workout App. Stryd will ignore the elevation data in these scenarios as it now knows that you are running on a treadmill. Therefore, power flattens out.

The Race Power Calculator works best if there is a good variety of run types. For example, running inclines and descents, a variety of paces, different temperatures, windy conditions, etc.

When only running on the treadmill at 0% incline, the following apply:

The Stryd Pod can be used as a foot pod sensor with many indoor running software, including Kinomap. As a Kinomap and Stryd user, you may notice a different power number in Kinomap than on other devices you are using, such as a Garmin sports watch.

The reason for this difference is that Kinomap is not fully integrated with Stryd Power. Kinomap will use the pace and distance measures that are fed to it from Stryd, but Kinomap performs its running power calculation using this data. The algorithm for running power in Kinomap appears to be more simplistic and thus is less reliable. For the best running experience with Stryd, you should use only the Stryd Power data for analysis. You can record this by connecting another device to Stryd by an ANT+ wireless pairing at the same time as a Kinomap, or you can use the offline sync feature from Stryd to see the data directly from your Stryd running power meter.

If you have additional questions about this, you can learn more at the Kinomap website.

The Stryd can be used on the AlterG treadmill but there are some limitations of Stryd with this treadmill.

Stryd will be able to give you accurate pace and distance for this treadmill but if you have Stryd with wind detection there will be issues with the calculated air power.

The AlterG treadmill uses air pressure to change the relative weight of the runner. This air pressure causes the Stryd wind sensor to inaccurately calculate air power.

Here you can see that Stryd thought Air Power accounted for 38% of the total power. This is not correct and has overestimated the average power for this activity.

If you choose to use your Stryd for the AlterG treadmill please reach out to support so we can remove the Air Power for these activities.