Beyond the Intervals: The Deeper Benefits of Power Meters

Power meters are great tools. They assess current physical ability, track training progress and improve performance, but those benefits are only the beginning. These devices allow for comparison of your physical abilities to competitors’ before signing up for a race. That gives you a head start in choose realistic tactics. Meters can even help you identify limits caused by issues beyond you physical capacities.

Critical power (CP) is the power a rider can sustain for a particular time. A “power profile” is the collection of your CPs over the complete range of times relevant to bike racing, from a few seconds up to a few hours. For instance, the most commonly used CP measurement is functional threshold power, which is the max power that can be sustained for a one-hour effort. The power profile is a snapshot of your physiological abilities and a convenient way to track training progress and identify areas for improvement. Comparing your power profile to that of your competitors provides a rough indication of how you should perform in races.

The power profile reflects the status of three energy production systems and your mental strength. The three systems are 1) The anaerobic alactic or phosphagen system, which provides most of the energy for efforts up to about 30 seconds. 2) The anaerobic lactic system, which provides most of the energy for maximal efforts from roughly 30 seconds up to six or eight minutes. 3) The aerobic system, which supports efforts lasting more than a few minutes.

A power profile doesn’t indicate efficiency, the ability to draft or race savvy, each of which are as important as raw physical talent. However, the profile does indicate how well you could expect to perform after optimizing those aspects.

Testing critical power at various durations develops a power profile. Then you can look up the power profiles typical of your category on line or in books about power training (eg. Comparing yourself to the standards gives some insight into your ability for particular aspects of racing. For example, a six-second critical power determines how quickly you can accelerate . If this number is near or above the typical level for your category, you’ll probably have a useful jump early on in a race. Of course, you need to also choose your gearing well. To have a good jump later in a race, you need both a high short-term power and efficient position and tactics to conserve energy.

Critical powers for durations between two and eight minutes indicate the ability to maintain effort through the final minutes of a race or during sustained attacks. A high four-minute critical power helps while bridging to a breakaway, or protecting a position in the front of a crit for the final lap or two. The critical power for two to eight minutes depends primarily on your anaerobic lactic energy system.

The 60-minute critical power, also called functional threshold power or FTP, indicates the power you’ll make in time trials. Because efforts longer than 20 minutes depend primarily on aerobic fitness, critical power can generally be predicted for times longer or shorter than 60 minutes from the 60-minute critical power . For instance, it is commonly assumed that 60-minute critical power is 95 or 96 percent of your 20-minute critical power. Extensive testing generally verifies the accuracy of this assumption. If your aerobic power is high for your category, you can do well in time trials and break-aways. If your FTP is high in proportion to your weight, you’ll also climb well.

Persistent Profile Problems

The thrill of progress is a wonderful part of starting a new sport. Novice bike racers can expect rapid progress in all aspects of fitness, skills and performance. Speed improves, along with cornering, sense of pace, drafting, and judgment of how much to eat and drink. Early on in a career, every ride is an opportunity for progress compared to the previous outing. Eventually, you will plateau, and further improvement will require a new angle.

Developing a power profile and then looking for the holes will help personalize training. If your FTP is category three, but your six-second critical power is category 5, you need some strength development, either in the gym or on the bike to develop your sprint. (Old timers would say, “if you are getting to the end of the race but moving backwards in the final meters, you need to work on your sprint.” Same thing.) If your four-minute critical power is competitive in your category, but your FTP isn’t, focus on aerobic development.

Tip: If your critical power for a particular duration or your power at a particular heart rate has decreased despite focused training, don’t increase the training! Power only decreases despite maintained training when you are tired, hungry, dehydrated, sick or overtrained. Rather than pushing, rest and then start training up again. Oscillating fitness from one day to the next often means there are issues with nutrition, hydration or sleep, while reduced fitness that lasts more than a few days indicates fatigue.

Power profiles determine what you need to do to progress, but eventually even knowledge of weaknesses has minimal returns if you’ve reached your physiological limits. No matter how much they train, some people can and some can’t develop 1,200-watt sprints, or the ability to sustain 375 watts for an hour.

In fact, the best sprinters are limited in their sustained aerobic power, while the best time-trialists have limited sprinting ability. To have a phenomenal critical power for six seconds or even two to eight minutes, you have to have an unusually high percentage of fast twitch muscle fiber. This implies a low percentage of slow-twitch fibers, limiting aerobic power. In fact, Well-trained athletes have a strong correlation between VO2-max and fiber type percentages. A Low VO2-max indicates high fast twitch and low slow twitch fiber counts.

Identify the areas of weakness in your power profile and attempt to fix them, but when the holes in your profile don’t respond to training, eating, sleeping, massage and hydration, that doesn’t mean you are forever doomed to be pack fodder. Some races and tactics favor a big sprint or five minutes of hard effort, while others require a higher FTP. By choosing your races and tactics appropriately, you can pick up prizes even if the critical power tables say you are out of your league.

Get Real

Choosing races that suit your skill set and power profile will improve results more than years of training. If your maximum sprinting power is much lower than your competition, you are not going to win head-to-head sprints. If victory is your goal, entering races that traditionally end in field sprints is a waste of an entry fee unless you can somehow break away. If you are heavy or your FTP is low, don’t plan to win hill climb time trials. The World Track Champion doesn’t enter hilly road races, and except for a few super-heroes, the best climbers from the Tour de France don’t waste their time in criteriums. Still, there are more forgiving races where a variety of power profiles have the potential to win, if the tactics match the profile. For instance, stages of the Tour de France that go over Mont Ventoux have been won by pure climbers (eg. Gonzalo Aja of Spain in 1974) and by time-trialist/leadout men (eg. Eros Poli of Italy in 1994. He was 6’4” and 198 pounds at the time.)

Sprinters Play Dead

A pure sprinter (ie. A rider with high critical power for times under one-minute but low FTP) can win a flat or rolling road race, even a hard one, provided that he or she is realistic about abilities and behaves accordingly. Sprinters don’t pull. They know that they will win if they get to the end of the race with the leaders, and that they’ll be dropped if they trade pulls with FTP riders. It is the job of sprinters to suck wheels, and the job of everyone else to try to get rid of them. A sprinter who arrives fresh at the finale places well. A sprinter who is forced to use up his or her sprint chasing breaks and closing gaps won’t have the gas for the finale. When other riders look to a sprinter to pull in a break, the sprinter does not oblige because the sprinter knows that it doesn’t matter if the break is caught.

The rider with a high FTP but poor acceleration will not win at the end of a race with true sprinters still in the pack. That’s a given so such riders need to avoid that situation. If avoiding getting dropped is more important than winning, such riders can sit in and lose, but if winning is more important, they need to at least try to break away to win races that would otherwise end in field sprints.

Rouleurs on Hilly Courses

What do you do if you are a strong rider but know you’ll be dropped on the climbs? If you wait for the climb to use your matches, you’ll be off the back and out of the race. That is a given. Instead, you must attack long enough before the climb and establish a gap before the ascent. You know the pack will eat your gap on the ascent, but if they catch you at the top or near it, you can hold on. Remember that all tactical decisions are gambles. By choosing tactics suited to your power profile and weight, you may win some races that don’t match your body type. Recognizing their strengths and weaknesses, FTP riders can sometimes win “easy” races, and sprinters can occasionally win on harder courses.

Tip for Improving Climbing, Maybe: Speed on climbs over a few minutes duration depends on the ratio of aerobic power to weight. If you have a high FTP but are also heavier than competitors, you’ll climb poorly. Strive to clean up your eating to lose excess body fat, but what about excess muscle? Muscle mass, even leg muscle, weighs you down as much as fat, but that doesn’t mean that everyone should lose muscle to improve climbing. If you outweigh your competitors but also have a relatively high FTP, losing weight will make you climb well. If your FTP is low despite training, you probably have a good sprint. When sprinters lose muscle mass, they lose sprinting ability but do not become competent climbers. If your FTP is low for your category despite a good year of aerobic training, forget about leading in races with long climbs and don’t worry about getting super light to improve your climbing.

When Results Don’t Match the Profile

Experienced riders and good coaches know that high numbers are only a small part of the story. In your appropriate category, you can only win if your tactics, nutrition, recovery behaviors, aerodynamic and so on are as good as the other riders. If your power profile says you should be winning but you aren’t, look to those other factors. Even in the high categories, more riders lose because of poor cornering skills, pack position and cadence than because they just aren’t strong enough to compete. You can develop a power profile and train on your own, but if you are not living up to your profile and you aren’t sure why, rather than just train harder, talk to some other riders or a coach and get some guidance about what else to work on. Focusing soley on fitness when you have more room for improvement in other areas is counterproductive. Worse yet, don’t expect racing to be easy. If the critical power tables show that your profile is up to snuff and you expect a smooth path to victory, you’ll lose. Racing is hard. You have to be mentally ready to use all your strength and skills.

Power Meters – Not Just for Training

Power meters are great for controlling training sessions and monitoring progress but if you stop there, you are missing much of what they can do. Through the power profile, you can identify areas for physical improvement and compare yourself with your competitors, helping you dial in race tactics and identify skills and other areas for performance improvement.