Thursday, July 11, 2013

How to Use Your Power Meter to Your Best Advantage in a Triathlon

By Hunter Allen, PCG Founder/CEO/Master Coach

(reprinted from Tri Magazine)

After training and pushing yourself to the limit preparing to take all of your hard-won fitness and do your best on race day, the most important thing on the bike will be pacing yourself correctly. Most triathletes do not understand how easy it is to ride too fast on the bike leg. It’s the number one cause of DNFs in triathlons. The difference between a well-paced bike leg and a poorly paced one can be as little as fifteen watts (normalized) average in the event. It’s not just about average watts, though; it’s about how you produce those watts, how many “surges” you make during the triathlon, and whether you go harder in the beginning or save some for the finish. All of these factors can dramatically impact your run time.

How you’ll produce watts is the first consideration when developing a tri racing strategy. Not all watts are created equal. You can create a thousand watts by pedaling in the 53:12 gear at a very high force but slow cadence, or you can produce a thousand watts by pedaling in the 39:21 gear at a low force but very fast cadence. The watts are the same in the end, but you called on very different muscle-fiber types to produce them. More fast-twitch (Type II) muscle fibers are recruited when you are pedaling in a high-force, low-cadence situation, whereas more slow-twitch (Type I) fibers are recruited in a low-force, high-cadence situation.

I use a tool in TrainingPeaks’ WKO+ software called Quadrant Analysis to help you understand exactly how you create watts. Quadrant Analysis takes your power data and plots it in four different quadrants so you can see exactly how you created your watts. Quadrant 1 is high force and fast cadence, like sprinting. Quadrant II is high force and slow cadence, like climbing a steep hill or pushing a big gear. Quadrant III is your endurance pace with low force and slow cadence. Quadrant IV is low force and fast cadence, more like a criterium.

Quadrant III is predominantly the Quadrant you want to be in during a long-distance triathlon. Why does this matter? It matters because of the energy expenditure in both situations. When fast-twitch muscle fibers are recruited, more muscle glycogen is used in the contractions than when slow-twitch fibers are recruited. One of the key things for a triathlete to do is to pedal as smoothly and steadily as possible. By keeping your power output as smooth as you can, you save valuable energy for the run. By smoothing your effort on hills and avoiding bursts of wattage, you can keep your pedaling variability low and therefore reduce the amount of muscle glycogen used on the bike leg.

Just as when a car’s your fuel consumption will be much higher if you are constantly flooring it and accelerating hard at every chance you get instead of driving smoothly and consistently, your muscle glycogen expenditure will be greatest on the bike when you are fluctuating your power between low and high forces. I’m not necessarily advocating always using a high cadence in triathlon. I am, however, advising greater mindfulness about how you create your watts in a race. Stay light on the pedals, use your gearing to keep your cadence consistent, and, if you’re a “gear masher,” spend plenty of time in training trying to achieve a more consistent, smoother pedaling stroke. Your pacing strategy should include being able to choose the correct gearing in such a way as to minimize excessive glycogen use.

The next most important use for your power meter is to know the pace that you should adhere to in order to give it your best on the bike, but still have a PR on the run. That first begins with knowing your functional threshold power or FTP.  Your FTP is your best average power that you can produce for one hour. How do you find it? There are two ways: 1) Go out and do your best 1 hour effort at the edge as HARD as you can go. If you don’t have a suitable location for an hour effort, then 20 minutes will do. Do your best 20-minute effort and then subtract about 5% off that number. The result will be very close to the same power you would do in an hour, or your FTP. 

Once you know your FTP, you can begin to make a pacing strategy based on the length of your race. In the book I coauthored with Dr. Coggan, Training and Racing with a Power Meter, our chapter on Triathlon goes more in depth with pacing and presents case studies by successful triathletes. We put together a pacing chart below for you to use in order to help with the various distances you might race in.

Pacing for triathlon, based on your functional threshold power
*NP is Normalized Power, or the power you would produce if you pedaling smoothly for the entire event. This is a metric created by Dr. Andrew R. Coggan and is used in TrainingPeaks’ WKO+ software. Intensity Factor is a measure of intensity of your effort in relation to your threshold power, so .83 is roughly 83% of your threshold power.

A power meter is more than just a training tool. It’s a tool to help you achieve the best performance you can on your day. Not all watts are created equal in cycling, and how you create the watts is a very important part of your bike leg. Just pushing the biggest gear you can is a mistake, and you will likely pay for that mistake on the run. As we all know, the sport of triathlon is largely a sport of pacing, and pacing yourself in the bike leg is probably the most important place to be mindful, as going too fast can ruin your run time, and going too slow will give you a subpar overall performance. A power meter tells you exactly how hard you’re going in a race, whereas pacing by heart rate can be very deceptive since heart rate is affected by heat, hydration, sleep the night before, and a number of other things.

Use your power meter in both training and racing to help you be more successful in whatever distance triathlon you are competing in.