Using Power Meters in Training

Bike power meters (PMs) have been around for a while now and are gradually coming down in price as technology matures and the market evolves, meaning they are accessible to more and more people. Not to be confused with Power Balance Bands, PMs actually do something useful and in all my years of training, racing and now coaching, I rate PMs as the most valuable tool for training and racing that I've ever used.

This article is not aiming to convince you to buy a PM - or which one - but rather to explain how, as a coach, I use PMs and the information they provide for prescribing training, reviewing training (and racing) and planning race strategies for the athletes I coach who have them. Equally, the athletes themselves are able to learn a lot about themselves and how they ride in order to become better athletes. An added bonus of knowing the principles of using PMs is that the same approach applies to running where pace is the equivalent metric to watts.

The starting point for using PMs is actually having a PM, of course, and having some familiarity with using it since your natural inclination when you first use a PM is to view it like a speedo and see how high and how long you can keep your watts up. Remember, use it as a tool and don't be a tool using it!! Once you've got and used a PM, you must buy and read the "bible" book called "Training & Racing with a Power Meter" by Andy Coggan and Hunter Allen...the 2nd edition has a valuable chapter on triathlons. This book explains concepts, terms and more that are essential for effective PM usage.

I've written previously that using a PM to guide training and racing has far replaced HR as a relevant measure of exertion to use for bike training...and similarly using pace during run training. It allows me to prepare periodised training plans where I can guide physical progress via the level of power and nature of sessions scheduled throughout the year. Additionally, a PM provides invaluable feedback in terms of reviewing and evaluating sessions completed, eg, did the athlete execute the session as planned, as well as a means for conducting routine testing to measure progress using a black-and-white measure of watts.

The following are the ways I use PMs in training and racing, which assume the athlete already has some familiarity riding with a PM for a couple of weeks.

Getting Started
The first step is to do a benchmark test, primarily to determine FTP (Functional Threshold Power) and some other metrics. Any testing should be done in a repeatable environment, where the conditions can be replicated the same each time - a velodrome or trainer are often the best options. Perhaps the two most useful testing protocols are either a 20 min TT (Coggan & Hunter) or 2 x 8 min (Carmichael), which can be extrapolated to determine FTP. Alternative testing is a Power Profile test (1min, 4min, 10min) or a MAP step-test although these are not as specific for determining FTP. Whichever approach is used, FTP watts is the outcome number you want (...and analysis of the test session file is also valuable).

Power-Based Sessions
Knowing FTP then allows structured and targeted sessions to be developed. Here's an example of a session for an athlete with FTP of 265w, aimed at VO2 max development:

25min W/U + 5 x 30sec spin efforts
5 x (2min @ 335-345w / 1min easy;)
5min easy spin;
8 x (1min @ 345-355w / 1min easy;)
5min easy spin;
10 x (30sec Hard @ 100rpm / 30sec easy spin)
20-40min W/D

Only two parts of the session had target wattages (5 x 2min and 8 x 1min), which are the key parts of the session. For this athlete it is understood that the warm-up/down and recoveries are done at an easy/moderate pace...however for some athletes wattage guidelines are necessary. The key reps are targeted at 125-130% of FTP (5 x 2min) and 130-135% of FTP (8 x 1min) and since the session is being done on a velodrome it is easy to achieve a steady power level. The 10 x 30sec reps are included without wattage targets to encourage smooth rhythm and technique without the "distraction" of a target, and is a good way to complete what is a very intense session.

For sessions done on a non-flat course, wattage targets are tricky since power fluctuates enormously and the ideal measure of Normalised Power (NP) is (mostly) not available until you download and analyse a session. In these cases average watts is the best alternative, however the athlete needs some experience and understanding to translate this figure into a meaningful and useful measure in this context. This is where analysis and familiarity with wattages by the athlete is a valuable learning out from using a PM.

Here's another example of a session, being an IM prep ride:

1:30hr easy
3 x (40min @ IM watts; 20min @ 1/2IM watts)
30-60min easy

In this case there are no specific wattage numbers, however I'm relying on the athlete - in conjunction with discussions we're previously had about suitable targets - to try different wattage levels. While there's a few models to determine suitable target watts for an IM race pace, ultimately these need to be tried out to see how the athlete copes in somewhat of a simulation training ride...which is key role of pre-IM sessions. Each of these rides, combined with post-ride analysis of the power file help to refine their target for optimal racing and pacing strategy, which are used in conjunction with other feedback measures like perceived exertion, HR, speed, and so on.

In summary, a PM allows you to structure almost any kind of session in order to achieve some objectives from it, throughout an entire periodised year of training.

Session Analysis
Once a session is complete comes the exciting part of downloading the files to a computer and analysing what actually happened. Suffice to say, you need to have an interest in this kind of thing to get the most out of the data...although a good coach will translate it into terms even my mum can understand!! While every session provides valuable information, structured sessions with some kind of focus provide the best information. Races provide the best "real life" analysis of how you ride.

In reviewing a power file you're actually looking at what happened during the ride, seeing things that the naked eye would have missed, which turns into feedback and input into structure for future sessions. For example, feedback to the athlete who did the first listed session included observations like this:

• His avg wattage was perfect for each of the reps, exactly in the target range. Also notable was the evenness of wattage within each rep - often reps like these will start with a spike in power and decrease thereafter. Power during the recovery was not important, only during the reps.
• HR was also consistent, following a typical pattern of reaching a stable ceiling in the second rep and reaching the same ceiling in each subsequent rep.
• The most notable thing from this session was his avg cadence, which went like this (2min reps) 96-96-97-93-90, (1min reps) 91-89-92-91-90-85-83-85. This was a notable drop in cadence which was explained as "Yes the common theme between both the 2 min and 1 min reps is as I tired and after the first few reps, I dug in and changed down a gear because I get more power at a lower cadence by pushing the pedals – the last 2 of the 2mins and the last 3 of the 1mins reps reflect this." In this case because the wattage was the target I wasn't too fussed how he generated that, so this explanation was fine.
• Further analysis using WKO+ software allows me to check the Quadrant Analysis scatter graph, highlighting each rep to see the associated distribution. While efficient cycling is generally in Quadrants III and IV, this session had significant distribution in Quadrants I & II which reflect the high force he was putting through his pedals.

Analysis of the second session includes consideration for altitude (hills) since it was on the open road and the wattages jump around a lot more although smoothing helps to even this out. Analysis from this ride includes things like these:

• Average and Normalised Power during the reps, and how much these vary. Ideal pacing has little variation between these two numbers which is far more efficient than wide peaks and troughs.
• Cadence is also reviewed in terms of consistency, particularly late in reps as fatigue builds.
• Similarly, HR trend as the session proceeds is an important measure of how the athlete was generating the power and the stress the body was under.
• Speed analysis is not so important, since the session is based on wattage targets...although speed can be confidence boost for the athlete to see as they ride.
• Quadrant analysis is more valuable in a session like this since it is a simulation effort and provides good "real life" data compared to controlled velodrome sessions.
• A session of this length allows evaluation of TSS for each rep as well as the overall session.

There's more things you can see by studying power graphs, peak power figures and so on...it takes some practice to know what to look for depending on the nature of the session or race. This analysis tells me how well the athletes are completing – and coping with – the sessions, which then feeds into progression in future sessions. It’s all about ensuring each session has an objective and that you’re getting the most from each session. Power analysis over time also helps in evaluating and managing workload and accumulated fatigue, which are great indicators of form.

Summary
This is just an overview of how power training can be used, and there's some real gurus in taking it to another level of detail. Nonetheless, for my coaching purposes a PM provides a fantastic level of insight and understanding into how athletes train and race, and allow me to use that knowledge to tailor their sessions to plan for and achieve the goals they're after. The same things can also be done with/for running using pace instead of watts. Either way, a PM and knowing how to use it is a wonderful tool in any athletes toolkit, and a huge benefit for the quality of service their coach can provide.