An Introduction to Power Meter

    Posted On Sep 01 2017

      By Shem Leong, Coach in Singapore, ironguides.net

      Do you have a power meter but isn’t quite sure on the best way to use it? Are you considering buying a power meter? Are you getting burn out from all the data oriented training your training have became since you started using the power meter? If you answered yes to any of these questions, this article is for you.

      INTRODUCTION

      This article is addressed to 2 groups of people; 1) Triathletes toying with the idea of getting a power meter and 2) Triathletes with access to power data either from a bike mounted system or on a turbo  trainer/ spin bike but have no idea how to interpret it.

      You’ve read about how power data is more accurate than speed and heart rate and that using power data to pace yourself is like ‘cheating’ on race day. You’ve no doubt heard the Fast Guys shooting off about their FTP and So-and-So’s power to weight ratio, their scary ‘Ironman Watts’ sessions that have been built according to Training Stress Scores and so on. Current power meter manuals will also instruct you how to use power data in many ways, including:

      • Simple ‘zoning’ of effort levels as a percentage of Functional Threshold Power (FTP – more on this below)
      • Pacing over the various distances of triathlon
      • Gauging fatigue levels and predicting the arrival of your physiological peak.
      • Determining what type of cyclist you are and your strengths and weaknesses
      • Aerodynamic testing

      While all this is good and to true, most everyday triathletes will struggle to use this information meaningfully. All you know is that the harder you pedal, the higher the power readings climb.

      If, however, you’re an advanced athlete that has already mastered the finer points of using power data, I urge you to move swiftly on from this very rudimentary approach to utilizing what is, at its full potential, a very sophisticated and refined training platform.

      Instead, this is article aims to give the reader a simple way to start using power data so that it is relevant to your daily training and that does not require the plotting and analysis of any graphs by you or a power meter expert. The methods underlined below are basic, not technical and obvious. In fact, this article simply reflects how I, a strictly ‘Perceived Effort’ kind of guy, have started using power data in my own training and with some of the athletes that I coach.

      _DSC1477

      GETTING STARTED

      Spend a few weeks rolling around with the power meter to get used to the relative magnitude of ‘a bunch of watts’. Note your typical range while riding at different perceived effort levels (Easy/Moderate/Moderate Hard/ Hard/ All Out) through various riding situations; Climbing, Descending, Sprinting, Time Trailing, Sitting in a draft, Riding into a headwind, Taking a pull, etc.  Don’t rush into it; give yourself time to get familiar with a brand new currency.

      The scope of this article will only require you to broadly grasp 2 technical aspects of training with power.

      • Functional Threshold Power (FTP) – is defined as the highest sustained power a rider can hold for 40 – 60 mins.

      Essentially, a rider’s FTP is a point of reference for their current level of bike fitness. For the beginner, raising your FTP is a good starting point – a tangible and quantitative goal to work towards. Knowing your FTP will also allow you to ‘zone’ different effort levels according to the ‘percentage of FTP’ that you are working at.  Current literature has defined 7 separate training zones but to keep this article simple, I only refer to the Lactate Threshold zone, which is most beneficial for increasing FTP.

      *Down the road, as you become familiar with training with Power, FTP can also be used to benchmark a particular point in your bike fitness. For example, if your FTP was 240 watts at your fittest just before an A race, and you are coming off an off season break with a current FTP of 200 watts, then you know how much room you have to improve before approaching race fitness.

      While there are several widely accepted procedures of obtaining FTP, the one outlined below is my preferred method. It is a relatively simple, albeit strenuous, procedure. Mount your bike on a trainer and complete this session as follows:

      Warm up:

      20 mins full warm up done as:

      3 mins easy – mod build /3 x 1 min very hard, 1 min easy/ 4 mins easy

      Main Test:

      30 mins best effort Time trial

      • Perform at the cadence that allows you to put out and hold your best effort.
      • For most triathletes, this will be in the 75 – 85 rpm range.
      • Lap the Power Meter at the start of this section.
      • Start slightly conservatively and build through the whole 30 mins
      • Beak it up mentally as follows
        • 0 – 10 mins @ 7/ 10 perceived effort
        • 11 – 20 mins @ 8 / 10 perceived effort
        • 21 – 25 mins @ 9/ 10 perceived effort
        • 26 – 30 mins @ All Out, empty the tank.
        • Finish with a very easy spin cool down

      Your FTP is the wattage from this Time Trail. Armed with this knowledge, you will now be able to perform a variety of training sessions at the right intensity to elicit certain physiological adaptations.

      • Normalised Power (NP) is the second concept that you need to understand. In simple terms, a rider’s NP is the average power, but adjusted for the range of variability (starts, stops, climbs, descents) over the course of a ride. Basically, it’s a more accurate reflection of average power when collecting data from longer rides out on the road. We can also use NP for tracking efforts on the trainer.

       

      TURBO TIME

      Power meters will be most useful for athletes that have already incorporated interval training into their weekly schedule. While it matter less where you do them (on the road or on the trainer), than that you do them, I believe that the quality of training you get from bashing out a set on the Turbo exceeds what you can get from doing a similar set on the open road.

      For the purpose of this article, I will highlight the 2 most important types of sessions for triathletes and how to use power data to get the most of out of them.

      1. Bike Tolerance

      Lactate Threshold sessions, done regularly, are designed to increase your FTP by developing both your cardiovascular tolerance (the ability to hold your effort at ‘redline’ for an extended period of time) and your neuromuscular skill (the ability to pedal at ‘race cadence’ in smooth efficient circles by training your muscles to fire in a coordinated fashion).  With a power meter, the intervals can be done at the prescribed intensity of 91 – 101% FTP. This will give you real time feedback within the session, if you’re pushing too hard or not hard enough or just the right amount.

      For Example:

      4 x 12 mins at 91 – 101% FTP / 4 mins easy spin off recovery between efforts

      See also:  Training: The Ups and Downs of Ironman Training

      Your power data can help you ‘fine tune’ the execution of these types of session. The goal for a rider with an FTP of 240W is to perform each of these intervals is between 218 and 242 watts. Say the 1st 3 intervals go according to plan at 220, 228, 234W but he fades on the last one and despite his best efforts is only able to put out 196W. We can deduce that if he had held back a touch on the 2nd and 3rd efforts, this would have improved his chances of getting that 4th interval within the prescribed 91 – 101% FTP.

      Without power data, the same session would be written as follows:

      4 x 12 mins hard / 4 mins easy spin off recovery between efforts

      While the results would have been very similar, the athlete without power data would need to reply on ‘perceived effort’ to adjust the intensity of the intervals in the following week in order to put out a ‘perfect’ session. But because he still reaps the physio-mental training stimulus of performing the session, his time on the turbo has not gone to waste. The addition of power data simply helps him to learn how to execute this session better. Of course, we assume that the athlete is teachable and thoughtful and indeed adjusts his efforts the following week(s) to finish the set ‘perfectly’.

      A stubborn athlete on the other hand, no matter what the power data tells them, will charge headlong into the session and execute it in exactly the manner, producing exactly the same result.

      The second way to use this data, is for the athlete to track their progression by comparing the average Normalised Power across all 4 efforts from week to week. An athlete without power data would need to rely on their own sense and feel as to whether they were getting better at this set of intervals or not.

      1. Bike Strength

      Excluding non- swimmers, the biggest gap for new and intermediate athletes is often their strength on the bike.  This issue requires immediate attention and the best remedy is to introduce a healthy dose of big gear work on the trainer. This involves working your legs against a much heavier resistance than you would normally encounter while riding steady on a flat road.   Think of this as doing cycling specific weight training. I start beginner athletes on 1 minute intervals done at 50 – 60 cadence.

      For example:

      20 x 1 min All Out / 1 min very easy spin off recovery

      • Maximum Cadence of 45 while @ maximum effort
      • Resistance on the recovery is as easy as you need it to be.
      • The more experienced athletes can go down to 30 cadence on longer intervals once the supporting structures in their legs and back have adapted to the higher load.

      When doing big gear work on the trainer, pushing very hard against a very high resistance will yield lower than expected power figures, relative to the level of exertion, because the resultant cadence of these types of sessions is so low. Therefore, in terms of matching perceived effort to power output, it is NOT useful to plug in a %FTP training zone, when doing Big Gear strength work, because the power figures, will not feel as though they match the effort you are putting out.

      Furthermore, pacing your efforts throughout the duration of Strength sets is not important at all (compared to Tolerance sets where the goal is usually to churn out paced power across all intervals). Strength sets is usually done pushing each effort as hard as possible (All Out) without regard for the next interval. As a result, the power figures from each subsequent interval should decrease as you progress through the set as your legs fatigue. In fact, I would be concerned that you were not pushing hard enough if you were able to hold the same watts over a whole series of strength intervals. After all, the main goal of this kind of session is to end with rubber legs!

      Instead, the average Normalised Power across all the efforts, ignoring the data from rest intervals, can be tracked each week for significant increases in strength over the course of a 6 – 12 week block.

      LONG RIDES

      As an athlete approaches Race Day, their long rides should start to closely resemble their race day efforts, in terms of Nutrition and Pacing and Power. With the lack of long continuous unbroken bike routes in Singapore, using multiple laps of a ‘low traffic, low stoppage’ loop will go a long way towards dialling in an athlete’s race day effort. The same looped effect can be achieved on a straight forward single out and back route by lapping the unit at predetermined points in the ride (every 15/ 30 / 45 km) depending on how you structure the ride.

      For power data collection on a race simulation, I like to break the ride into laps because:

      • It allows me to negate the first and final 20 – 30 mins of warm up and cool down riding to and from the start of the looped route.
      • It allows me to mentally break a long ride into shorter sections for better focus and pacing.

      With the exception of some of the hilliest half and full Ironman distance races, the best strategy is to ride at your best even paced power across the whole distance. This is where athletes with a better ability to gauge perceived effort will have an advantage over those that don’t. At the start of the bike, on fresh legs, your perceived effort will be lower than for the same power output in the middle of the ride as fatigue starts to build. Perceived effort will be higher again that tail end of the bike ride as the rider’s legs are already shot. Therefore, in order to ride an even paced bike leg, the athlete will need to control their effort continually and carefully, starting at a lower perceived effort and building naturally to a higher perceived effort to account for the accumulated fatigue as you progress through the ride.

      For athletes that are poor at intuitive pacing, a power meter can be a useful tool to help rewire the ‘Brain-Body Connection’ that controls pacing. Much like how data was used to perfect the set of Tolerance intervals mentioned above, so too can the power data on a lapped long ride help to accurately match perceived effort and power output across the duration on the long ride.

      For example:

      Using 12km loop done 6 x continuously (effectively a 72KM time trial) for 6 – 8 weeks leading up to a Half Ironman, is a nice way to replicate the race day scenario. Lapping your power meter after each lap will allow you to view your Normalised Power for each lap.  Here is an abbreviated set of data pulled from a longer 8 week progression of race simulation rides.

      See also:  Training : Nailing race day nutrition
      Lap / Week L1

       

      L2

       

      L3

       

      L4

       

      L5

       

      L6 Notes Ave NP
      Wk 1

       

      124 132 127 129 133 5 laps / group effort/  some drafting/ whole ride fasted / Full ride done big gear easy

       

      129W
      Wk 3

       

      120 132 133 153 153 160 6 laps /group effort / some drafting/ 1st half fasted / Full ride done big gear easy  – mod

       

      142W
      Wk 6

       

      162 168 206 174 176 143 6 laps /solo effort / Poorly paced/ 1st half fasted/ Full ride at race cadence

       

      172W
      Wk 8

       

      164 176 182 176 180 186 6 laps / solo effort / Well Paced/ race day nutrition/ Full ride at race Cadence

       

      177W

      Charting the data this way allows an athlete to cross-reference how hard they felt they pushed against a set of data telling them how hard they actually pushed.

      For example on Lap 3 on Week 6, the rider went for a ‘hot lap’ to test the consequence of a 20 min surge in preparation for such an occurrence on race day. While he was able to recover at race pace through Laps 4 and 5, his legs were too fatigued to hold this effort on the last lap, where his NP dropped significantly.

      After numerous weeks of ‘race-simulation’, and making the necessary tweaks to efforts and nutrition over the distance, taking the average Normalised Power across all laps, on a well-paced and well – fuelled ride (Week 4) gave this rider an NP of 177W that he can aim for in his coming race.

      The attentive reader will infer that the power data collected over this period has only played a partial role in his arrival at this level of race preparation. It was vastly more important that the rider was;

      • consistent with this weekly Race Simulation long ride
      • continually fine tuning his nutrition plan
      • controlling the training conditions to replicate race day conditions (i.e. drafting and cadence)
      • aware of the changes in his perceived effort as he progressed through each ride.

      All these elements that go into perfecting a Race Simulation are achieved without, and can sometimes be disrupted by the addition of power data. This athlete’s arrival at his NP target of 177W on race day is simply the ‘cherry on the pie’; a cherry that he could easily do without on Race Day, if the Race Simulation Progression was indeed completed in a satisfactory manner.

      IN CONCLUSION:

      A Power Meter is not essential or even necessary to improve on the bike. In fact, the majority of beginner to intermediate triathletes out there would benefit more from simply committing to:

      • Repeating, at least, 1 set of bike intervals a week –Spin Class does not count!
      • Executing their Long Rides, especially in the 8 weeks prior to an A race, in a structured, thoughtful and focused manner with an emphasis on race specificity.
      • Adjusting and fine tuning their effort levels purely according to feel

      Personally, I believe that Perceived Effort is a more intuitive way to train and develops a superior Brain-Body Connection; that understanding of what your body is capable of at its current fitness level. This is a critical and elementary skill that should be nurtured in all athletes at the earliest stage of their development because it gives them confidence in making training and race day decisions.

      For newer athletes, that have not yet learnt how to listen to their body, a Power Meter could in fact sabotage this learning process and cause confusion and frustration along the way. Consider these 2 scenarios:

      • While pure road cyclists can boast that they accurately track their level of fatigue and the onset of an approaching physical peak with power data derived Training Stress Scores, the Triathlete’s fatigue is a comprised of the sum of their swim, bike and run training loads. Currently, there is no simple way to quantitatively and accurately track the Stress Scores of swim and run training. So for triathletes, it is much better to be aware of your personal fatigue levels at any point in time, than to rely on a ‘bike only’ stress score.

      2015IMKona_WA8_1554

      For example, a Power Meter will tell you that you are not meeting the prescribed wattage for a particular set of intervals but it is only the Brain-Body Connection can attribute this decreased performance to the tough long run that the athlete battled through on the day before, or a poor nights rest or a dehydrated state or whatever combination of the above.  Without the Brain-Body Connection, the athlete would start questioning their ability and get frustrated at their apparent lack of improvement. On the other hand, the enlightened athlete would be content and assured to simply tick off that session and get on with taking the remedial steps to ensure that the next day does not become another ‘off day’.

      • Using a power meter to pace over long rides is one of its key selling points; just find your NP over a certain distance and plug in and play, right? In theory this is how it is supposed to work, but the ‘on-road’ reality plays out differently.

      On even a slightly rolling route, it is difficult to generate enough power while descending to match the rider’s target NP so we’re told to push over target NP on the climbs preceding them to compensate for this. While there are guidelines on how to handle various gradients and lengths of climb, I would go so far as to say that it would come as second nature, and be handled better by an athlete with a sound ‘Body – Brain Connection’.

      Don’t get me wrong, for all the power meter bashing that you may think I am doing, I do believe that a it can be a worthy investment if you are already fulfilling the training criteria above and are looking for a means to track your training quantitatively and to motivate you to producing and then subsequently building on that ‘perfect’ set of intervals / Race Simulation long ride, week after week.

      In the end, all I am saying is if you buy a power meter, or already have one; learn how to use it simply before getting bogged down with the advanced jargon and tricky functions. K.I.S.S!

      ***

      Shem leong, ironguides Coach in Singapore, ironguides.sg

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