Polar s810 Protects You From Overtraining

Polar s810 can measure your heartbeat intervals. The differences in these periods reflect your autonomic nervous system when it regulates your heartbeat. This measurement is most useful at rest or at low intensities, because we are talking about very small differences (msecs.) Your relaxation rate indicates the state of your physical recovery. If you are overtrained, it might very well be reflected on the Polar s810 monitor.

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Polar S-410 Gives a Rough Estimate of Energy Expenditure

Many heart rate monitors and bike computers has a feature to measure the energy cost of the exercise. But can we believe these numbers? I have always been sceptical to these calculations since they are based on very few variables (percentage of maximum heart rate and total time). I have always said to my riders that they can use these numbers for fun, but don’t count on them when they cook dinner. There is probably huge variability in the quality of calorie metres, some gives a rough estimate and some doesn’t.

Can heart rate monitors be used to calculate energy expenditure?

Yesterday I found a study published in Medical Science of Sports and Exercise that tried to figure out how accurate the energy expenditure calculator of the Polar s-410 heart rate monitor was. They used three different calculations of the energy expenditure: 1) Polar s-410 using predicted values of VO2 max and maximum heart rate. 2) Polar s-410 using actual values of VO2 max and maximum heart rate. 3) Indirect calorimetry (You might have heard about this one in school”¦)

The results showed that the Polar s-410 did a quite good job for the men with no significant differences between the three calculation methods. The women’s numbers were overestimated when using predicted values of VO2 max and maximum heart rate. The estimation was better when they used the actual values but still overestimated with 12%.

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Review of SRM, Power Tap and Polar


Kraig Willett has made a comprehensive review of the three most used power meters: SRM, Power Tap and Polar. He explains in details how these power meters measure power output and presents results from his tests. He gives us a very detailed review of how SRM, Power Tap and Polar perform in price, performance, and durability. The review might be a bit difficult to understand for beginners, but it is really worth reading.

Here are some of the points from Kraig Willett:

On how the SRM crank system measures power output
“Instrumenting a mechanical structure allows one to convert the phenomenon of interest into an electrical signal that can be subsequently analyzed, mathematically manipulated, and then displayed to the user. Strain gages do just that in the SRM power measuring device.

The strain gages that SRM uses are nothing more than a piece of foil embedded in a plastic carrier. The resistance of the foil element changes depending on how much it is stretched/strained. The strain gages unique characteristic of changing resistance under strain is what allows the mechanical deflections that naturally occur in the structure to be converted into an electrical voltage signal.”

On accuracy of power meters
“Additionally, it can even be argued that absolute accuracy is not an issue, but rather, consistency over time or measurement repeatability is most important.”

On installing a Power Tab hub
“The Power Tap system is just about as close to ‘Plug and Play’ as one can get. The straightforward steps of installing a cassette and a tire on the wheel built with the Power Tap hub are nothing too difficult for your average bike racer. Once these steps are accomplished, one must simply drop the wheel in the dropouts and install the receiver and CPU mount with the supplied zip ties. The whole process should take 30 minutes at most.”

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15 Super Gifts For Cyclists

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