cewait
DIS Veteran
- Joined
- Mar 3, 2000
- Messages
- 5,695
I have experience with three brands of foot pods; Polar, Nike and Garmin. Most of the following would also apply to others that are out there.
In technical terms, all foot pods are sets of accelerometers that convert the force of the foot strike and kick as you run down the path or on the treadmill. They have the advantage of not needing a GPS signal to give you pace and distance.
Foot pods MUST be calibrated for each runner since each of us has a slightly different stride. Also, a run/walker will need to follow the same pattern of running and walking during calibration to assure that the overall average is accurate. What I note is that a foot pod may be close on the run but horribly incorrect on the walk; or visa versa.
I would also re-calibrate on a 6-8 week interval just to assure myself that I am still running with a similar gait. As we become conditioned, the accelerations around the foot contact with the road will change; bringing the pod slightly out of calibration. This also applies when we are struggling with injury.
A final thought on the periodicity of calibration check calibration each and every time you change the battery, shoestrings or the shoe the unit is on. Basically, when you have the pod off the shoe and then reinstall, the alignment will change. I noticed that my pod was off about 10% or nearly a minute a mile when I changed out shoes. This paragraph may be moot for the Nike pod when it is used in a Nike shoe with the built in pod holder.
How do I calibrate?
The best method is to head to the local high school track and run one mile or 1600 meters depending on how the track is constructed. If the track is not crowded, take the inner lane and run in the very center of the lane. I use a running start for my calibrations and hit the start button as I pass the line on the track. I then run 4 laps and hit the stop button as I run past the line. The reason for the running start and stop is to avoid any readings where I may be hitting the track harder than normal. Most wrist units will give you the option of accepting the calibration. I know the Garmin starts off at 1000 as the factory setting. This is a unitless value. My stride yields a calibration value in the 925-935 range. With no adjustment to the watch, my indicated pace would be approximately 9 percent higher and the resulting distance 9 percent longer. Or in practical terms my 11 mile run is only 10. Worse, if I thought I was doing well running a 16 minute pace on the uncalibrated unit I would be shocked to find that I was actually only running a 17:20 pace.
In technical terms, all foot pods are sets of accelerometers that convert the force of the foot strike and kick as you run down the path or on the treadmill. They have the advantage of not needing a GPS signal to give you pace and distance.
Foot pods MUST be calibrated for each runner since each of us has a slightly different stride. Also, a run/walker will need to follow the same pattern of running and walking during calibration to assure that the overall average is accurate. What I note is that a foot pod may be close on the run but horribly incorrect on the walk; or visa versa.
I would also re-calibrate on a 6-8 week interval just to assure myself that I am still running with a similar gait. As we become conditioned, the accelerations around the foot contact with the road will change; bringing the pod slightly out of calibration. This also applies when we are struggling with injury.
A final thought on the periodicity of calibration check calibration each and every time you change the battery, shoestrings or the shoe the unit is on. Basically, when you have the pod off the shoe and then reinstall, the alignment will change. I noticed that my pod was off about 10% or nearly a minute a mile when I changed out shoes. This paragraph may be moot for the Nike pod when it is used in a Nike shoe with the built in pod holder.
How do I calibrate?
The best method is to head to the local high school track and run one mile or 1600 meters depending on how the track is constructed. If the track is not crowded, take the inner lane and run in the very center of the lane. I use a running start for my calibrations and hit the start button as I pass the line on the track. I then run 4 laps and hit the stop button as I run past the line. The reason for the running start and stop is to avoid any readings where I may be hitting the track harder than normal. Most wrist units will give you the option of accepting the calibration. I know the Garmin starts off at 1000 as the factory setting. This is a unitless value. My stride yields a calibration value in the 925-935 range. With no adjustment to the watch, my indicated pace would be approximately 9 percent higher and the resulting distance 9 percent longer. Or in practical terms my 11 mile run is only 10. Worse, if I thought I was doing well running a 16 minute pace on the uncalibrated unit I would be shocked to find that I was actually only running a 17:20 pace.
