> Also, I think these things must measure oxygen (input - output) being > consumed rather than air intake. This is a little more sophisticated > than just measuring volume of flow since oxygen and/or carbon dioxide > content must be measured. O2 uptake would be much more meaningful than air intake. PC: this is true, but it would take more costly equipment, a simple heart monitor paddled over a longer steady state corse would yeild a relative comparison that would be useful. Of couse pure O2 uptake would be better, and if you are comparing the same person with different paddles, again you would get a reasonable comparison, you would get very different values from one person to the next depending on their metabolism, conditioning, etc. >However, it does bring up the issue of repeatability in tests. I'd like to know how one measure energy out accurately. While a knotmeter and GPS combo can give decent speed estimates, they'd have to be integrated over time and compared to O2 uptake over time as well. Then you'd have to know the speed vs resistance characteristics of the hull. You do not need any of this information to make a valid comparison. the same hull, at the same gross weight, at the same speed will take the same amount of power to push it though the water (presuming wind and currents are not a factor). What you get a the same power output with each paddle, what would vary is the amount of O2 uptake, or heartrate (once stablized to a steady state condition). Since presumable the O2 or heartrate would vary, the lower the O2 uptake, or heart rate, the less work the paddler is puting into the paddle to mantain the SAME speed (or power output). You do not need the to know the speed vs. resistance of the hull to measure relative paddle efficiency. Peter *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 20 Sep 2004 at 10:05, Peter Chopelas wrote: > PC: this is true, but it would take more costly equipment, a simple > heart monitor paddled over a longer steady state corse would yeild a > relative comparison that would be useful. This is true - cheap and dirty O2 uptake tests are simply time over distance tests that are calibrated for weight etc. You run/cycle/whatever for a given time, measure the distance (or vice versa) and look up a table of O2 uptakes required to do that for typical people of a given weight and such. However, the question is then whether the errors in this kind of test are sufficiently small to differentiate between two paddles. If tests results for the HRM vary by 5% and the paddles differ by 3%, you won't see anything reliable. HR vs O2 uptake can be thrown off easily by things like CO saturation level - if you hang out in a smoky bar the night before the test, you'll pump more blood per unit O2 than if you stay out in the fresh air. Ditto if you spend several weeks vacation hiking high up in the mountains and then perform the test at sea level - you'll pump less blood per unit O2. > You do not need any of this information to make a valid comparison. > the same hull, at the same gross weight, at the same speed will take > the same amount of power to push it though the water (presuming wind > and currents are not a factor). The key then is to oblige the paddler to a paddle at a specific speed. It would be wise to choose a speed that is not too high, so that it can be achieved with a wide range of paddles. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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