Understand Your Rowing Numbers – Power/Watts

Let’s start this series off with what is hopefully the easiest number to interpret – power/Watts.

Power is simply the amount of work done (aka energy delivered) to the machine, in a given amount of time. It’s measured in Watts, similar to measuring the power of a light bulb or microwave oven. One important thing to note – Watts displayed by the rowing machine reflect how much work the machine receives from you, NOT how much energy you use to deliver that work. This will become important later when we talk about calories.

The rowing machine measures your power by continually recording the speed of the flywheel. By comparing the difference in speed of the flywheel during your drive and your recovery phases, the machine calculates how much energy was put into (and subsequently lost by) turning the flywheel.* Dividing this amount of energy by the time taken to complete the stroke gives us power.

We recommend that if you’re just starting out rowing, use the power statistic to guide how hard you are pushing yourself. This is because the number of Watts changes directly in proportion to how hard you row – e.g. if you pull twice as hard, you’ll see twice as many Watts on-screen. Thus tracking your (average) power output is the most straightforward and intuitive way to track how much you improve. This isn’t the case for split, which we’ll talk about in the next post.

One final note about the power number: although the number is updated every stroke, the machine actually displays the average of your last two strokes. That’s why you may notice a one-stroke delay if you change your effort level very suddenly.

That’s it for our short lesson on power/Watts. Next week, we’ll talk about pace (aka split).

*: It may be of interest to note that by using this method to calculate your power, the machine effectively cancels out any random errors (e.g. air density, humidity, dust, friction in the bearings, manufacturing errors, etc) so that the power measurement is consistent across machines. While it is beyond the scope of this series to delve deeper into how the machines work, feel free to ask your instructor about this if you’re interested. We may do another series of post on this topic in the future.

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