Real Science, Real Simple: Tailwind Coaching

Coaching: Beginner’s Guide to Power (part 1)

Posted on July 10, 2012 | in Coaching, power, Training | by

Quarq Cinqo InstalledTraining with a power meter is consistently hailed as the next step for any cyclist who is looking to improve on their fitness.  While that's true, most cyclists who are in the market for a power meter are hesitant to purchase one.  The biggest reason I've run into is hesitation on how to actually utilize such an instrument.

But why?

Powertap HubA power meter is wonderful and spits out bucket loads of data, but the one thing that it won't do is make you faster.  It will, with some practice and some simple analysis allow you to train to become faster.  In this series of articles, we'll look at a few of the basics that beginning power meter users need in order to train smarter.

Definitions

It helps to know what we're talking about, right?  So let's take a look at some power training terminology.

Functional Threshold Power: Abbreviated FTP, it is the measure of wattage you can produce at one hour without fatigue.  This roughly corresponds to lactate threshold or anaerobic threshold, and is best measured by a 60 minute TT (although there are other ways we'll discuss later.)

Power to Weight Ratio: A simple mathematical formula, usually expressed in Watts/Kilogram (of body weight) that essentially defines the ability to propel yourself (and your bike) down the road.  Raising this ratio is typically a key to improving your racing and training success.

Power Training Levels: Along with FTP, these dictate (roughly) the energy systems used at certain power levels and allow a rider to train specific systems to get specific gains.

Power Profile: One of two metrics that will help to identify strengths and weaknesses.  It is also a key way to determine if you are putting too much time into one specific energy system and neglecting others.  It determines power/weight ratio for various "critical power" points and gauges them versus usual power/weight ratios for various racing categories.

Fatigue Resistance Profile: The second key to identifying strengths and weaknesses.  A fatigue resistance profile helps you to determine what your "winning strategy" should be.  Will you be the drag racing sprinter who goes from 300 meters out or the guy who can blow the doors off a Ferrari in the last 50 meters?  Do you solo in from the 5K to go climb or do you save it for the Flamme Rouge?  The fatigue resistance profile helps you tailor your strategy to your strengths.

We'll start with an overview of FTP and power to weight, with the other factors being reviewed in later posts.

FTP

As stated above, FTP is a measure of how many watts an athlete can produce for an hour without fatigue, and is an excellent measure and predictor of performance.  It is also the basis of all workouts and is how we determine effort levels for intervals.  It is also considered to be our "100%" level.  You know  from experience that if you go out and hammer for all you're worth for about 1 minute, you certainly can't maintain that pace for much longer.  If you go out and spin easy, you know you can probably do that for a long time.  Essentially, it boils down to this: efforts below FTP are sustainable, efforts above FTP are not.  So how do we find our FTP?

While calculating FTP through a true 60 minute TT is the ideal way to determine what your FTP is.  But let's be realistic: there are very few times we're willing to sit on a trainer for an hour and pedal at TT power.  If you're outside, the chances of finding a route with few hills, cars, intersections, stop lights, stop signs and little variable wind is just about nil.  Add to the fact that very often indoor and outdoor (if you can manage them) 60 minute FTP tests yield quite different results.  Bearing all those factors in mind, ideally you'd have a 60 minute (25-ish mile) TT from a race which you can reference, because that is the best way to measure FTP.

20 Minute FTPBarring that, a 20 minute test is the next best thing.  A 20 minute TT is much easier to accomplish both indoors and out, and simply multiplying the 20 minute average power by .95 will give you FTP (within a few percentage points of accuracy.)  For example, the an athlete does his "20 minute test" and he averages 233 watts over 20 minutes.   Multiplied by .95 gives us 221 watts FTP.  Remember this number for later, because this will be our "100%" effort that we base our power training zones off of.  It is also what we use to predict power to weight, which is a good predictor of performance.

But what does that mean?

Power to Weight Ratio

As stated before, power to weight ratio is a key determinate in cycling performance, particularly when climbing.  It is important for time trialling as well, and it gives a good picture of how successful an athlete can be.  Take our athlete above with the 221 watts FTP.  Assuming he is a larger athlete, say about 180 pounds (about 82 kilograms) he would have a power to weight ratio of about 2.6 W/Kg (228W/82Kg.)  This would put him in the Cat 5 level of racing.

However, if the same wattage were produced by an athlete of 65Kg, he would have a power/weight ratio of about 3.4 W/Kg.  This would put said athlete squarely in the Cat 4 level.

Power/Weight ratio

Imagine the implications of simple weight loss then?  Every pound shed increases the power/weight ratio, making weight loss "free speed" at the end of the day.  This will be most noticed in hilly terrain where it's well known that carrying around extra weight will do nothing but slow you down.  Consider the graphic above: that 65Kg rider only has to ride about 30 watts over threshold in order to get into the 4 W/Kg realm of a decent climber.  That 82Kg rider has to put out around 331 watts in order to hit 4 W/Kg.  Assuming both riders have the same FTP, the 82Kg rider needs to ride at 150% FTP just to keep up with the skinny guy!  You'll see later on that this is near on impossible due to the energy systems involved.  Now if that's not motivation to lose a few inches off the midsection, I'm not sure what is.

But weight loss is another topic altogether, and the real way to get a benefit from your power meter is to use your FTP to design workouts, which we will cover next time in the Beginner's Guide to Power – Part 2.

 

Comments?  Thoughts?  Questions?  Post below and start the discussion rolling.

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