Why is There a Discrepancy Between the Distance Recorded on My Apple Watch and Treadmill?
Many individuals experience discrepancies in the distance recorded by their Apple Watch’s exercise ring and the distance shown on their treadmill, especially when one kilometer on the treadmill is only registering as 650 meters on the watch. These discrepancies can be attributed to several factors. Let’s explore these in detail:
Improper Stride Length Estimation
The primary source of the discrepancy is the difference in stride length experienced under different conditions. Your stride length may vary depending on whether you're walking or running outside or on a treadmill. This can cause significant differences in step count calculations.
Devices like the Apple Watch and treadmill meters use standardized step length estimates, often based on user inputs such as height and gender. The watch may be using a stride length estimate that does not match your actual stride or that differs significantly from how you walk on a treadmill. It's important to understand that steps-based distance estimation can vary depending on speeds or the number of steps per minute taken. Therefore, while GPS is generally more accurate for outdoor activities, treadmill activities may rely on step-counting methods.
Wrist-Based Pedometer Limitations
Another factor contributing to the discrepancy is the limitations of a wrist-based pedometer, particularly when using a device like the Apple Watch. Wrist-based pedometers can struggle with step counting during treadmill activities.
For instance, if you are holding onto the rails for a significant part of your treadmill session or if you're using a treadmill while walking a bike outside, where your hand holding the watch is resting on the handlebars, it becomes challenging for the watch to count your steps accurately. This can result in an underestimation of the distance.
Calibration of Treadmill Distance Meters
On the other hand, the treadmill itself is designed to measure the actual distance accurately, provided it is calibrated properly. Treadmills use physical measurement methods to track distance traveled, ensuring a more reliable reading.
However, it's important to understand that your watch and exercise ring use a pedometer-style estimate of your distance. To estimate the distance, these devices multiply the number of steps taken by the stride length. The Apple Watch, for example, uses a technique similar to that of a Garmin watch, which requires multiple runs to estimate the user's stride length accurately.
Example of Other Devices
For a practical example, consider the experience with a Garmin watch. While not exactly precise, it does offer a good approximation of distance on a treadmill. A Garmin watch, after several runs indoors, can estimate a user's stride length and provide surprisingly accurate distance measurements, sometimes within just 5 meters of the actual treadmill meters for a one-kilometer run.
It's worth noting that while these devices strive to provide accurate distance tracking, they rely on assumptions about stride length based on user inputs and may not always match personal biomechanics.
In conclusion, the discrepancy in distance measurement between your Apple Watch and the treadmill can arise from variations in stride length, the limitations of wrist-based pedometers, and the accuracy of distance meters in different situations. Understanding these factors can help individuals better evaluate the reliability of their fitness tracking devices.