31 August 2007

Power Reserve

I hope that you enjoy this article -- this is a very interesting concept that Terry shared with me last year. He's taken to time to write up his thoughts, more fully, for us here.

You can contact Terry through his website, linked below.


Terry Kerrigan and Dr. Philip Skiba


We should probably introduce ourselves, and let you know why we are writing this together. Terry is an Ironman pro, and is the CEO of Aperion For Life, Inc. He coaches and trains athletes across a number of sports, and brings substantial personal experience to the table. Dr. Philip “The Other Dr. Phil” Skiba specializes in sports medicine and exercise science with a focus on endurance athletes. He is the CEO of PhysFarm Training Systems. Though he coaches a small number of athletes, he primarily works as a consultant and advisor to elite and professional athletes around the world, helping to direct their coaches and trainers to design better programs. PhysFarm then uses the data gathered to design new technologies to better prepare athletes for competition.

Terry and Dr. Phil work as a tag team to train a small number of highly motivated athletes. Terry provides much of the practical advice and training progressions, while Dr. Phil provides the science, analysis, and direction. This approach has been very successful. For example, we work together on Joanna Zeiger’s training. She went from a string of tough races to 15th at the Edmonton ITU race, to 1st at Boulder Peak and 2nd at 5430 Long Course.

We are often asked about our coaching “style” or “approach.” We encourage our athletes to stop thinking in the generic wastebasket terms of “bottom-up” or “top-down” coaching. We treat each athlete as a unique individual with particular strengths and weaknesses to be exploited or improved. We believe in applying the art of coaching to the latest science to develop a logical, evidence-based strategy that yields results time after time.

The Concept of Power Reserve:
Before we can talk about the concept of “power reserve”, we should discuss a few definitions so that we are all on the same page.

Functional Threshold Power (FTP): Coined by Dr. Andrew Coggan, this is the best average power an athlete can maintain for an exercise task that takes about an hour. It is highly correlated to the Maximal Lactate Steady State, that is, the highest intensity of exercise an athlete can perform and still maintain a constant level of lactate in the blood, rather than a continual increase. It is primarily due to the metabolic fitness of the muscles, that is, the ability of the muscles to use fat for fuel, and spare carbohydrates (which are limited).

VO2max: The maximal amount of oxygen the athlete can use during exhaustive exercise. It is primarily due to the ability of the heart to deliver blood to working muscle, as well as the number of capillaries in the muscle. pVO2max refers to the power required to reach VO2max, and is usually quite close to the best average power an athlete can maintain for about 4 to 6 minutes.

Using these concepts, we can put together an organizational framework in our minds. If you think of your fitness as a house, imagine that the foundation of the house is your “base training” or perhaps more appropriately, your overall ability to tolerate specific Ironman training. Let’s think of your absolute best sprint power output is the peak of the roof, your VO2max as the attic, and your FTP as the ceiling. Your performance ability (race power) is equal to your height, and you mark your height on the wall as you grow. Make sense?

First things first: You need to train before you can train. What we mean by this is that you need a period of months to years of general training so that you have a foundation that can support the house. What you are doing is allowing your body to build the appropriate infrastructure to support everything you want to make it do. Put another way, as Dr. Andrew Coggan has pointed out: the more you train, the more you will be able to train. We don’t just go out and try to race an Ironman. We spend years training and racing shorter distances before moving up to the ultra distance stuff.

Once we have a solid foundation and are sure the place won’t collapse, we can move into the house and begin to “grow up.” By performing specific training, you begin to get taller. As you grow, your head gets closer and closer to the ceiling. Eventually, you need to raise the ceiling or you will bump your head, right? So, by training in certain ways, we can raise that ceiling. But now, you have another problem…your attic space is getting smaller. To make more space, you have to extend the attic higher. Yet, this eventually creates another problem…you can’t make the attic any taller than the roof. At some point, you need to raise the roof.

When we say “Power Reserve”, we are referring to your “headroom.” We are referring to the amount of power you have available to you above what you actually need to perform the way you would like in the race. Practically speaking, this Power Reserve also reflects an RPE reserve. When the roof, attic, and ceiling are high enough, you have plenty of headroom and you don’t feel cramped/stressed at your chosen race power. The goal of good coaching is to figure out the best way to improve your headroom.

For example: Let’s consider power requirement for a task vs. an athlete’s maximal capacity developed in training. The task is a 180k bike leg in about 4h30m: 68 kg athlete, good aero position, appropriate equipment. Let’s say it takes 265 watts to accomplish this task. How stressful this is, and how well the athlete will run afterwards, depends on their Power Reserve. In other words, if your maximal ability for 180k is 275 watts, and you rode 265 watts, you are going to be shelled and will likely run poorly. However, if your maximal ability for 180k is 290 watts, 265 watts will feel much less taxing.

There are both smart ways and a silly ways to generate that 265 watt average. You could constantly vary your power, or ride steady. Both mathematical modeling and practical experience indicates that your best bet is riding steady, with plenty of reserve, and minimizing your forays into ceiling / attic / roof territory. (However, you should also note that in very variable terrain, a more variable power approach is more appropriate.)

Developing Your Height vs. Developing Your Headroom

The important thing to remember is that the division of exercise efforts into “zones” is a purely artificial, man-made process. In other words, exercise is a continuum where riding done at FTP not only improves power at LT or MLSS, but also serves to improve pVO2max and fatigue resistance. Likewise, riding done at pVO2max will also serve to improve FTP. However, we think in terms of zones so that we train in a time efficient manner and can focus in on particular aspects of fitness.

Traditional training theory would have you believe that the area between LSD training and threshold training is essentially a “no-man’s land.” We have found that, at least in ultra-distance athletes, there is significant gold to be mined here. We have found that while the athlete’s headroom increases with more intense training, increasing the athlete’s height (90k to 180k race power) is best achieved by what we call directed LSD riding. In other words, the athlete does not simply ride long and slow. Rather, the athlete rides in a directed way with extended periods of time at a high LSD / low-end tempo pace. An increase of just 5-10% results in very significant gains in terms of Ironman race power over the long term.

Why Are We Talking About Power Instead of Heart Rate?

Exercise science tells us that (at least below VO2max) HR is the effect of, not the cause of performance ability. You select an exercise level, and your heart simply tries to meet the demand. For instance, we regularly witness HR variations in a range of +/- 15bpm at the exact same power output in Terry’s training! If we had followed a strict heart rate protocol, we would have likely over or under-trained him in a variety of training blocks and circumstances.

The problem is that HR is affected by all kinds of stresses, whether that’s deconditioning, exercise duration, temperature, hydration status, or psychological state. Too many athletes micro-manage HR as if it’s the cause for adaptation when in fact it’s a result of many ongoing changes both chronic and acute. A power meter tells you exactly how hard you are working at any given time, and allows you to very carefully monitor and distribute your effort over the course of a race to make sure you do not push too hard and blow up

The idea of gauging effort in this way is nothing new. For example, look at swimmers and runners: HR monitoring has not really infiltrated the highest levels of these sports. The best athletes have trained on the basis of pace / split times (in other words, power) and duration. The oft-cited Dr. Jack Daniels (and if you don’t own a copy of his book, turn off your computer, go buy it, and don’t read anything else until you finish it) has managed many elite and professional athletes on this basis. Power monitoring will allow you to monitor your training similarly on your bike.

Now, this does not mean that HR data is useless. However, to make it useful, you need to use in under very controlled conditions and keep the above caveats in mind. For instance, it is possible to look at the ratio of HR:Watts in a controlled (indoor and cooled) environment. This is a bit beyond what we can cover in this rather general article, but the point is that there is a place for HR monitoring…just not what most athletes and coaches think it is.

As A Practical Matter, How Do I Apply These Concepts?

This is purely a coaching question, and will be different for every athlete. However, we can give you some general guidelines about our approach to athletes.

1. Know what system you are training.
Set up appropriate zones a la those developed by Dr. Coggan. You can look around on the Internet for a .PDF he authored on the subject, or pick up the book he co-authored, “Training and Racing with a Power Meter”. Dr. Skiba’s book “Scientific Training for Triathletes” also has a short primer on this.

2. Build your foundation.

“Base Training” isn’t (or rather, shouldn’t) be about just going long and slow. LSD training is important in this context, but you must always address the other systems: Anaerobic capacity (<1-2>20 minute power) to optimally prepare your body for everything you will ask of it later. Pure LSD training to the exclusion of all else prepares you to go long and slow. Is that how you want to race? We refer to LSD as Long Smart Distance Adaptation, very specific power per energy system and progressing the duration.

3. Go short and fast before you go long and fast.
This is also known as “reverse periodization” or “raise the left, fill the right”. In other words, you increase how many watts you can make, then work on how long you can make them. Early on this may mean working on your short term power (a couple of minutes) and extending that power out to 4-6 minutes. This raises the roof and attic. Then, you do the same thing for your FT and later race power. You start out with a directed long ride that includes a few 15-minute intervals at race power. Later in the season, you will extend those intervals to 20 or 30 minutes. As you reach peak training load, you gradually cut down the rest interval. You will come to a place where you can ride at your desired race power very steadily and without great variation for many hours.

4. Don’t do anything in the race you didn’t first do in training!

This might be the most important rule. Prove to yourself you can do it in training before you try to throw the smack down in a race. If the best you have ever done for 180k is 220 watts and you try to push 260 watts, you are asking for a 6 hour marathon that will leave you praying for death. You would be surprised at how many people do exactly this. Just because you feel like Superman at the end of your taper doesn’t mean you are faster than a speeding bullet. Stick to the plan.

The Big Picture:

As you apply these concepts to swimming and running, it is important to remember the big picture. The body adapts to stress according to some pretty well defined principles, the most important of which are specificity and progressive overload.Specificity means just what you think it does: at the end of the day, you need to run to become a better runner and bike to be a better biker. There is very little crossover between sports, and this has been proven scientifically. (To be strict about it, there is some minimal crossover, but this is of more importance to novice and/or severely detrained athletes). Progressive overload means that you slowly overload the body such that it adapts to the new stress level. In mythology, Hercules became strong by carrying a small calf up a hill every day. Each day, the calf grew a little, which made his “workout” a little harder. Hercules achieved great strength through a process of overload. He didn’t carry the calf one week and then a bull the next week. Catch our drift? You can’t do it all at once…it needs to be gradual.

But, just how long is “gradual”? We are talking years. Seriously. More often than not, athletes “overshoot” mentally. They attempt an overly ambitious training program and expect a result that isn’t in keeping with the time periods of physiologic adaptation. They think in terms of weeks, months and race seasons, when in fact it takes years (as many as 10) to come to peak ability. The results of “overshooting” are often frustration, injury and health complications. In desperation, the frustrated athlete then begins investing too much energy in things that don’t provide any proven gains. They look to enhance results with supplements, swimming aids, or special running shoes, and become still more frustrated when they fail to meet expectations.

There is no easy way. Achieving your potential is about hard work, being honest with yourself, and having a deep level of commitment to becoming your best on your body’s terms, not your ego’s terms. There is no replacement for things like a healthy lifestyle, sleep, good nutrition, and above all, patience.


Above all, the most important concept we can convey to you is that your training program must be based on evidence; that is, real data. How fast can you swim 4k on a day-to-day basis in training? How many watts can you put out and for how long can you put them out? How fast can you run from 20-40k? How about after cycling for several hours? This is what you need to know to design your training program properly, and just as importantly, how to optimally plan and execute your race. Good Luck!

Aperion For Life, Inc. bridges the gaps between sports performance, lifestyle development, and health and wellness, providing thoroughly planned and effective solutions to fitness related challenges. Read more at www.aperionforlife.com

PhysFarm Training Systems, LLC is dedicated to helping clients in amateur and professional sports achieve excellence in athletic performance through the application of the latest science and state of the art technology. PhysFarm develops custom training strategies for clients interested in lifting performance through legal, scientifically validated means. More information is available at www.physfarm.com