Power meters provide wealth of data for athletes to mine in pursuit of stronger performance

You can't open a cycling website or magazine now without seeing a pro cyclist with a power meter on their bikes. But what is a power meter, what does it do and why would you want one?

First off, a power meter is a measuring tool. It measures the torsion (twisting) of a bicycle part that has been twisted as a result of your pedalling. This can be measured in the "spider" (the bit between the chain rings and the crank), or in the hub, on the twisting of the chain itself. There is even a new company coming out with pedals that will measure your power.

Power is torsion multiplied by angular velocity, and angular velocity in cycling is cadence or how fast you pedal. Power is output in watts, and you probably have heard of cyclists referring to the wattages on a climb, in a race or even on TV. So, when you hear that Lance Armstrong can hold 450 watts for an hour, then know 450 watts is really, really hard to do for five minutes, much less an hour! The typical trained cyclist can average 250 watts for an hour. Keep in mind this is also dependent on weight, so a cyclist who weighs 115 lbs (52 kg) and produces 250 watts for an hour has a much higher power-to-weight ratio at 4.8 watts per kilogram than a rider who weighs 180 lbs (81 kg) for a power-to-weight ratio of 3.0 watts per kilogram. Power-to-weight ratio is king in cycling, so the amount of watts per kilogram of body weight a cyclist can produce is incredibly important to their success.

Wattage is the measure of work you can do on a bicycle. While heart rate can be used to measure intensity of effort, it is dependent on rest, hydration of the rider, outside heat and humidity. Heart rate is a response mechanism to work. Wattage is the "dose" and heart rate is the "response." If you are, or have been, training with a heart rate monitor, then you are basing your training on a "response." But, what has been the cause of that response? Why did your heart rate go to 150 beats per minute? Was it because a dog just chased you? Was it because you just did a hill sprint? Was it because you are just hyped up and sitting on the start line ready for the race to begin? Heart rate gives us some information, but it does not tell us how much work you are doing. That's what a power meter does.

Once you have forked out the dough for your new power meter, gone through the laborious process of installing it on your bike, calibrating it, charging the computer and figuring out how to use the buttons, you might ask yourself, "How do I use it to improve my cycling?" Great question, and that's exactly what you will want to do with your new training tool. A power meter does not make you a faster rider the same way putting on that new set of fast wheels does, or when you drop one pound off your bike with some new carbon fibre widget.

You are going to have to think, understand and utilize all of the information that your new power meter provides to you. Power meters collect a tremendous amount of data (five to seven channels of data collected at one-second intervals), and you will have to make sense of it to ultimately improve your cycling. I have come up with some basic steps to get started on the fast track to training with a power meter.

COLLECT DATA
Your first mission is to simply ride with the thing on your bike and download every ride. Every ride has importance and every download is key to your understanding. Don't change your training for the first week or two - just follow your normal routine and collect the data. These downloads will begin to give you some valuable information on your current training: how much time you spend in your new power training zones, at what wattage level you consistently pedal, your preferred cadence, how many kilojoules it takes before you significantly fatigue and so on. In this first step, your goal is learn some basic things about yourself as a cyclist that you will be able to apply later in your training, in order to improve.

TESTING BEGINS
The second step in this process is to learn your functional threshold power (FTP). FTP is defined as the highestpower that a rider can maintain for approximately an hour in a quasi-steady state without fatiguing. When power exceeds FTP, fatigue will occur much sooner, whereas power just below FTP can be maintained considerably longer. This means your FTP is your best average watts for an hour time trial. There are many ways to find out your FTP, but the best one is just to hammer all-out for an hour and see what you can do. Unfortunately, as you might know, this is a painful but necessary part of the process. You will need to test for your FTP many times in the future, as this is one of the best ways to see how much you have improved over time. (For all you "shortcutters" out there: do 20 minutes as hard as you can and then subtract five per cent from it - this will give you a very close approximation of what you could do for an hour.)

ESTABLISH POWER TRAINING LEVELS
Once you know your FTP, then you can determine your power training levels. The power training levels are anchored around your FTP, with Level 4 (smack dab in the middle of the seven levels) defined at 91 to 105 per cent of your FTP. With your FTP as 100 per cent, the rest of your training levels can be defined.

Understanding in which level you are training is critical to helping you to create the training response you are looking for. If you want to improve your anaerobic capacity, make sure your intervals are between 120 to 150 per cent of your FTP power. This ensures you are training in the correct level to induce training adaptation.

POWER PROFILING
Figuring out your relative strengths and weaknesses is next. Exercise physiologist Andrew Coggan, PhD, and I created the power profiling chart initially in order to help riders compare themselves to the best in the world, and also to compare themselves with their racing peers. However, once created, it ended up becoming a very important tool in figuring out the type of rider you are and what areas you need help in.

Are you "really" a good sprinter? Are you "really" a time trialist?

By comparing your wattages with your power profile, you will be able to tell exactly your strengths and weaknesses and also what type of rider you are. Unfortunately, figuring out your power profile involves more testing!

In the testing for your power profile, you will need to test your best five-second, one-minute and five-minute wattages. These represent your Neuromuscular (Level 7), Anaerobic Capacity (Level 6) and VO₂ Max (Level 5) wattages respectively. The easiest way to test these is on a day when you are fresh and not tired from a long block of training. You will crack out your best numbers when you are rested. The importance of learning your power profile cannot be understated. What your relative strengths and weaknesses are will determine your training plan to attack and improve your weaknesses, while watching your strengths improve, as well.

WATTAGE-BASED WORKOUTS
The final step is to adapt your old training ideas, habits and patterns into wattage-based ones. Since you are now training with your power meter and using wattage to guide you, you will want to change your intervals to wattage-based ones in order to elicit and create the greatest training adaptation. Training specifically in your current training levels will guarantee you are using your training time most efficiently.

When training in levels 1 to 3, look at your average power for the entire ride to make sure you are training correctly, and don't kill yourself by trying to pedal in a narrow wattage range for these lower levels. At the same time, if you are doing an endurance ride in Level 2, don't attack the hills like it's the world championships, and then "putt" around the rest of the time to keep your average wattage in the Level 2 percentages.

When training in the more intense levels 4 to 7, you will want to hold your wattage as best you can in the level you are training. These intervals are shorter, more intense and will require focus to maintain the correct wattage and keep yourself honest in your effort.

Training with a power meter is about results. It is worth doing only if you have a clear understanding of what needs to be done. If your information about your training is limited, then you are limiting your ability to improve and you are ultimately limiting your success. Enjoy training with power.

7 Tips for Using a Power Meter

1. Learn how to use the interval function on the computer head unit. Mark your intervals. Each time you do an interval, "mark" the start and stop, so that you can review them on the road and also find them easily in the downloaded data.

2. Learn your FTP - Functional Threshold Power - the best power you can maintain for an hour. If an hour test is too much, then do a 20-minute test and subtract five per cent from that average wattage, which will be close to your FTP. Test every six weeks to capture fitness improvements.

3. Power is stochastic. This means that your wattage is highly variable, but not quite random. It's hard to hold to a certain wattage number, so choose a range to hold within as your power fluctuates from pedal stroke to pedal stroke.

4. Download your data every day into a software program. Every ride is important, from your rest days to your hardest interval sessions to your races. Download every day and see how that fits into the big scheme of things and also to analyze a part of each workout.

5. Don't pedal. Conserving energy is the name of the game. How much you don't pedal is important for racing and long rides. Save those legs for the end.

6. Pace yourself. This is a sport of pacing. We happen to like to do it on bicycles. Learn to use your power meter to better pace your efforts on climbs, flats, in a fast paceline, over a long ride and even pace your nutrition by looking at the amount of kilojoules burned in the ride (1kJ = 1.1 kilocalories).

7. Training Stress Score is a valuable tool. Learn how many points each ride scores and then get a feel for how much time it takes you to recover from those rides. If you ride as hard as you can for an hour (your FTP), then you score 100 Training Stress Score points. Relate all your rides to this gold standard.

About the Author

Hunter Allen and Andrew Coggan co-authored Training and Racing with a Power Meter and blog about the research at www.trainingandracingwithapowermeter.com.
One of the world's foremost experts in training with power meters, Allen co-developed TrainingPeaks WKO+ Software and is the CEO and Founder of the Peaks Coaching Group. He is a USA Cycling Level 1 coach and former professional cyclist.

"Power Up Bike Training" first appeared in the 2010 July/August Summer Sports Issue of IMPACT Magazine.