Power Training III: Critical Distance
Here’s something the power meter industry doesn’t want you to know. You can measure power output without a power meter. OK, it’s not really a big secret, but this segment of the training series brings us back around to my original notion of “Training with the concept of power.”
The Power Mindset
To me, power, more than a number or a graph or a measurement of any kind, is a concept. It’s the concept that when we ride, train and race, our number one concern over all others should always be putting out (or conserving) power in the most effective manner possible. For the most part, this is just a slight shift in the psychology of how we ride, but it can make a very real difference in the energy you expend and the efficiency of your training and racing.
I think one of the biggest mistakes most riders make when doing intervals, is that they focus on pedaling “harder”. Pedaling harder conjures up the image of mashing on the gears, rocking your body back and forth, and grunting and groaning a lot. When you make the mental shift in your training from pedaling harder to pedaling with more power, suddenly all of that wasted energy turns into smooth, even acceleration and a constant and efficient force on the pedals. Power monitors display this concept very clearly as you can instantly see your wattage with every turn of the pedals, but even without a power meter, a rider can learn to understand the difference between hard riding and efficient riding.
When you make the mental shift of changing the focus of your intervals from “harder” to “more powerful”, you start to understand the essence of doing a proper interval. As hard as this is for most riders, sometimes (especially on the shorter intervals), you must stop looking at heart rate and start looking at miles per hour. Focusing on road speed might seem to be a bit of a throw back to pre-HRM training, but in fact, when used properly, it can actually be quite useful.
Two Riders were in a Bar…
One cycling conversation that never ceases to amuse me is the one where two riders brag about their average speeds for two totally different training rides. In this conversation, a benchmark of 20 mph is usually the holy grail of cycling accomplishments and anything above that is just gravy. Unfortunately, because of things like wind and hills, average speed for a long ride is a rather useless measurement of the effectiveness of a workout. However, in a controlled environment, miles per hour or distance covered in a certain time frame can actually be very telling and make for a handy alternative to a power meter.
Time-Based Field Testing
There are basically three predominant intervals lengths that I use in my own training and in my coaching. These are 15 minutes, 3 minutes and 1 minute. Of course there are others ranging from a 2 hour zone 3 interval to a 15 second sprint, but for our purposes here, these are the three we will focus on. For each of these lengths, I have my clients choose a different stretch of road that has a marked starting point and an easily identifiable finishing point (such as mailboxes or road signs) so they can tell how far they have traveled on each interval.
When doing this for yourself on your own training ground, you should find a section of road with a consistent grade that is free of obstructions that could affect the speed of the interval such as stop signs or traffic. Other factors like wind should also be minimized either by choosing an area with a consistent wind in either direction or one that is protected by trees or buildings. Doing the intervals at the same time each day can also minimize airflow variations. If possible, it may be useful to have two courses for each interval length, one flat and one with a grade.
Once you choose your courses these will be your test tracks for the remainder of the season. Do a trial on each of the 3 courses to see the maximum distance you can cover in the given interval length. The most distance you can cover for each of the 3 time periods is similar to what the power meter crowd calls CP or Critical Power. This distance can then be used as a bench mark for all future intervals. Let’s call it CD or Critical Distance.
This does not mean that every interval over the course of a month has to be done on the exact same section of road. Not only would this be incredibly boring, but it would also decrease the effectiveness of the training because the body would become very efficient at riding from, say 7th street to 21st street rather than adapting to a variety of different terrain. Doing one or two intervals per week on your chosen section road should be sufficient to improve the effectiveness of your interval sessions as described below.
The first advantage to doing your intervals using CD rather than Heart Rate or Perceived Exertion is that it will force you to focus on putting all your energy into making the bike go faster (power) rather than using wasteful movements that might increase ventilatory rate or heart rate but don’t necessarily do anything to increase speed. Second, it will encourage more consistent intervals. A high heart rate as your primary objective will often lead to an overly aggressive start to the interval and a taper near the end, but when CD is the goal, you will quickly discover that a smooth acceleration and even tempo over the course of the interval will lead to the best results. This is true not only for each individual interval, but for the entire set. If you find that the CD of the 3rd and 4th drops off significantly, it may be an indication that you blew your wad on the first two.
Critical Distance as Diagnostic
The CD can also be used over the course of a training block, not only to measure progress in fitness (as your CD increases), but also to help you or your coach better understand your body’s limits and prevent over training. For example, you might have 6, 3 minute intervals on your schedule. The first 2 might be great but then on the 3rd, you notice a sharp drop off in CD. This could be a fluke, so you might try one more interval. If the result is the same, this is a strong indication that the training session is over because you are no longer putting out the necessary power to invoke a worthwhile training effect. Thus, rather than do two useless intervals, tiring yourself out unnecessarily, you would end the session early and get some extra rest so that you can come back stronger for the next workout.
Similarly, near the end of a hard 4 week training cycle, you might come out and find that even your first and second intervals are well off the mark of your best interval. This is an indication that the training block might be too long or that you are tired from other factors such as stress or illness and that it is time for a rest week. I will often give a rider one more interval session during a training cycle than I think they can handle. If they get to that day and their CD or CP is way off from the gun, they can roll home easy no harm done. However, if they complete the session successfully it tells me that maybe they can handle that extra day of intervals each month and it will allow me to improve the efficiency of their training schedule.
Finally, perhaps the most important problem solved by using CD rather than heart rate to measure interval quality is the avoidance of the inevitable frustration that so many riders feel at the end of a month of hard training when no matter what they do, they cannot get their heart rate “up”. Even though they have all read my articles (see Training with the Concept of Power 1 and 2) and heard me explain to them over and over that a decrease in heart rate over the course of a training cycle is unavoidable, many riders can’t get rid of that nagging doubt that there is something wrong with them or that their intervals aren’t good enough because their heart rate is lower than it was at the beginning of the month.
When invariably I get that worried phone call each month from one of my riders wondering what is wrong with them, I can simply inquire about their CD or if they have a power meter, their CP and from there, we can work out whether there is an actual problem or if it is just a case of over-reaching (normal training exhaustion).
So many riders take themselves out of a race or training session before it even starts, because their legs feel tired or they feel worn-out. The indisputable proof learned from training with power or the concept of power, that even a feeling of extreme fatigue doesn’t necessarily negatively impact performance can be the most valuable weapon any rider can have in their arsenal. On day 6 of a stage race, everyone is feeling tired, but the rider who knows from experience that that feeling of exhaustion is just that, a feeling, will often have the mental edge that puts them over the top.
In the final article, I will discuss the advantages of having the hard data from an actual power meter and the basics of what to do with that information and how to put it all together.
Josh Horowitz is a USCF Certified coach and an active Category 1 racer. For more information about his coaching services check out contact [email protected] or check out his website at