by Hunter Allen
One of the many reasons to train with a power meter is the ability to determine optimal training load. Should I ride two hours or four hours today? Should I do intervals or just ride easy? Are ten hill repeats enough, or would fifteen make me stronger? How many hours or miles should I ride this week? Does more always equal better? There are elaborate schemes on how to periodize your training based on miles, hours, racing category, age, and geographical location. Some are based on heart rate, some on mileage, and others on goals and available hours to train. All are designed to answer the same question: How much is enough?
Click through to decipher the answer…
I think Joe Friel said it best in The Cyclist’s Training Bible: “An athlete should do the least amount of the most specific training that brings continual improvement.” If you can win the race with ten Vo2 max intervals, why do twelve or fifteen? I remember reading this and thinking it was flawed because I didn’t have a way to know how much was enough. I mean, I love riding my bike as much as the next guy, and I’ll ride extra miles just because it’s fun, not because it’s just enough to give me the win on Sunday. In my mind it was only a guess as to how much training stress I needed in order to achieve the fitness needed to win. Since it’s just a guess, and since I’m ever the over-achiever, if I think ten Vo2 Max intervals are enough, I’m going to do twelve or fifteen just to be sure.
Enter the dawn of the bicycle data acquisition device, the power meter. With a power meter, you can record every effort, every ride, and every race; quantify your exact training load, or dose; and then watch your progress to learn your training response. The ability to understand how you respond to training stimuli is paramount to answering the question of how much is enough. If you do ten Vo2 max intervals two times a week for a total of eight weeks and then see that your Vo2 max power has increased by 30%, you’ll know the training worked. Conversely, maybe you only do those intervals once a week and in eight weeks see no difference in your Vo2 max power, or maybe you do them for ten weeks and your Vo2 max power doesn’t increase significantly after week eight.
Before we consider the big picture, we need to first examine the daily training needed. In order to do this, we need to understand the relationship among intensity, time, and the energy system we’re trying to improve. Let’s say Joe Athlete wants to work on his Vo2 max power. From Dr. Coggan’s training zones, we know that Vo2 Max is stressed when you are between 106% and 120% of your functional threshold power (FTP). So the intensity must be in the correct training range in order to cause enough stress on the energy system we’re targeting (in this case the Vo2 Max) to stimulate improvement. At the same time, the effort must be maintained long enough to stress that energy system. If you rode at 120% of FTP for only thirty seconds, that wouldn’t be long enough to actually cause adaptation. For the Vo2 Max system to adapt to training stimulus, a minimal effort of three minutes is necessary with a maximum time length of about eight minutes. After eight minutes it’s very hard, if not impossible, for most people to maintain 106-120% of FTP.
Once you understand the relationship between time and intensity, you’ll be able to set some guidelines for how many intervals are optimal for you to do on a workout basis. For instance, if you’re trying to improve your Vo2 Max system and want to prepare for an upcoming event with eight five-minute climbs in it, you’re going to do eight five-minute intervals between 106-120% of FTP (let’s say 300 watts). In the first interval you’ll crack out 360 watts, 350 in the second, and 340 in the third. This third interval is what I call the repeatable interval; the watts you do in that interval are the watts you can repeat over and over. The first two efforts are always fresh efforts, in which you have plenty of glycogen in your muscles and a lot of anaerobic work capacity available to crack out the big watts. However, once that anaerobic work capacity is used up, you’re left with just the right amount of energy to repeat more efforts.
The reason this is so important is that we’re going to take the watts in the third effort and subtract 5% from it (in this case 340 x .05 = 17 and 340-17=323 watts), and when you can’t average at least this many watts (323) in your interval, you stop, because you won’t be training intensely enough in order to elicit a great enough stress to cause a training improvement. Maybe the sixth interval is 320 watts, and because you are an overachiever (aren’t we all?) and want to make absolutely certain you’re cooked, you do one more interval. By minute two you know you can’t even maintain 310 watts, much less 323. This immediately lets you know that you are now below the intensity needed to stimulate the Vo2 max system and you can’t maintain the time needed to create enough stimulus for improvement.
The chart above can help you to understand exactly when to stop doing interval repeats based on that telling third effort. This requires a bit of mental math out on the training ride, but as long as you know the percentage drop-off to look for in each time period, you should be able to quickly and easily figure out how many intervals are optimal for each workout.
In the example below of an athlete’s Vo2 Max workout, we see the other side of the coin. In this case, the athlete could have done more intervals to gain even more training adaptation. This is a perfect example of using these interval guidelines to ensure optimal training. This athlete’s watts didn’t drop at all from the first interval to the third one. In fact, they actually went up! Unfortunately he stopped after the fifth interval when he could have easily done another, if not two or more.
Since we’re all limited by the time we have to train, and because we all want to train most efficiently, it makes sense to use the power meter to figure out our optimal number of training intervals for each workout. Not only does it make sense, but it allows us to take advantage of Joe Friel’s maxim, “Train just enough for success.” With a power meter we are now able to quantify the optimal training load in the grand scheme, and with some simple guidelines, we can truly optimize your training each day.
We’re all also limited by our ability to recover and our ability to adapt to training stress, so these will always be a limiter in our fitness improvement. But wouldn’t it be nice to improve at the highest rate you can? Of course it would. If you use my interval guidelines you can be sure you are training optimally. As a coach I use the power meter to its fullest to make sure my athletes train optimally. Train to your optimal level, and you’ll be assured of success!
Hunter Allen is a USA Cycling Level 1 coach and former professional cyclist. He is the coauthor of Training and Racing with a Power Meter, a co-developer of TrainingPeaks’ WKO software, the CEO and founder of Peaks Coaching Group, and a PCG master coach. Hunter can be contacted directly through www.PeaksCoachingGroup.com.