Cycling Training with Power

Power meters are gaining popularity in the cycling community and this has been aided greatly by the vast choices of power meters on the market currently, which has made owning a power meter a possibility for the regular amateur and professional alike. Finally, power meters are becoming affordable. Currently, there are various types of power meters available; but the three most common types are the crank-based, pedal-based and wheel hub-based power meters. Each of these have pros and cons. Some are more expensive than others, some are easily interchangeable between different bicycles and others claim to be more accurate than others. Regardless of which option of power meter is chosen, power meters are very useful tools in improving cycling performance.

A lesson from Heart Rate Monitors

When heart rate monitors became widely available to the general public in the 1990’s, they too were useful tools for training and racing, yet at the time, most athletes used the heart rate monitor as a type of ‘rev counter’. People knew what their heart rate was, but they never controlled their heart rate enough to make good use of the technology. The heart rate monitors were largely used as interesting pieces of information rather than making use of the information to control training intensities closely. The same pattern is emerging in the use of power meters; a great number of people are missing the point and missing out on making best use of what many coaches and athletes consider to be the most valuable training and racing tool to have been invented, for cycling. Heart rate monitoring has now become an adjunct to the power meter, and monitoring power on the bike has replaced heart rate monitors as the gold standard of effort prescription.

Here is why:

As Sports Science gained in popularity, scientists developed protocols to determine levels of blood lactate accumulation, which revealed the state of intramuscular glycogen metabolism (Glycogen metabolism is the process of either building up glycogen, which is the body’s way of storing carbohydrate, or breaking it down to fuel the body. An increase in the blood lactate level implies that the glycolytic or glycogen break-down process is becoming increasingly saturated. Basically, the demand exceeds the supply, due to limitations in “supply chain”). At the time, power meters were not available to the general public and so these intricate measurements of blood lactate were associated with corresponding heart rates, which was a tool that could be easily used. People would incorrectly assume that heart rates associated with blood lactate levels in the laboratory, were the same as in the real world. For example a person would say: “My threshold is 167 beats per minute.” But, the reality is that their heart rate was 167 beats per minute, at ‘lactate threshold’, only under the same intrinsic and extrinsic conditions as the when the test was conducted, and these conditions could include:

• Temperature (higher temperatures elicit higher heart rates, independent of muscular power)
• Time of day (Circadian rhythm has an effect on heart rate, independent of muscular power)
• When they last ate (The gut requires blood, and the less blood that remains in circulation for muscular work, the higher the heart rate will be, independent of muscular power)
• Hydration status (Dehydration elicits higher heart rates independent of muscular power)
• Humidity (More humid climates elicit higher heart rates independent of muscular power)

If these conditions are not met in any and every workout, heart rate cannot be used as an accurate reference of intramuscular metabolism nor of blood lactate concentration that was previously measured. You see, heart rate is affected by so many factors, other than muscular power, that it becomes a very rough tool to use, and there are many other factors that can affect heart rate, other than the ones I have listed. Muscular power and metabolism, on the other hand, are very closely linked, independent of other variables. Power is a direct measurement of energy transferred from the body to the pedals, and measuring this is a very accurate tool to pin-point correct intensities in every training workout and also to pace oneself accurately over the course of long distance events. Heart rate, however, is a great tool that can and should be used if you want to monitor the actual heart or total body stress, taking all intrinsic and extrinsic factors into account, but it should not be used to prescribe training or racing efforts in relation to the levels of lactate in the blood.

The Physics of Power measurement

Power is measured in Joules/second or Watts, after the inventor James Watts. The Joule is a measurement of energy. Therefore Power is a measurement of energy in relation to time. With regards to rotational systems, such as in a bicycle crank arm driving a chain, the determination of this measurement of power is defined as Torque x Angular Velocity. In other words Power is equal to the force applied to a rotational system multiplied by the speed of the rotation. Basically, this means Power is determined by how hard you push on the pedals multiplied by how fast you can turn the pedals.Increasing force, cadence, or both will produce an increase in Power. As you can see, cadence is an integral component of Power and the improving the cyclist’s ability to ride at a higher cadence should be a part of the training program. Likewise, there should be a focus on improving the muscular strength of the cyclist, so that they can produce more force with each pedal stroke. This too will improve Power. These two components are the foundation of improving a cyclists Power.

Cadence is important

There have been many tests and studies which have tested efficiency at various cadences, and most tests have concluded that cyclists are most efficient at a cadence of 75-90 rpm. This has led some coaches to train their athletes exclusively in this cadence range. These tests and studies very rarely assess the effect of high cadence training on the ability to produce power, or efficiency, following months of adaptation to training at high cadences. The same applies to studies which assess adaptation to training at low cadences. We know, from looking at training methods of the best cyclists in the world, that both of these strategies are very effective in improving cycling Power.

To summarise this point, for a cyclist to improve their Power:

There must be an increase in the ability to produce force which can be achieved by training at low cadences, or there must be an increase in the ability to turn the pedals faster (and to sustain the increased turnover), which can be achieved by training at high cadences, or a combination of both. In addition to the two fundamental components of Power mentioned above; force and cadence, if a cyclist is to improve their performance, they will need to improve the amount of work that they are able to perform. Work could be described as Power over the course of time, which brings us back to the measurement of energy, the Joule:

Power = Joules/second. Work = Power x time (seconds), therefore Work = Joules/second x time (seconds). Therefore Work is measured in Joules. This is a convoluted way of describing energy, but relevant in the context of the individual components needed to produce power, and the energy needed to do so over a period of time. As we unpack this further, the relevance will become apparent. The longer a certain Power can be held, the greater the Work performed. We not only need to be able to improve our cycling Power by being able to push harder and turn the pedals faster; we improve by being able to sustain that power for increasing periods of time. For an endurance athlete, the amount of Work that can be performed, and the rate at which it can be performed are the crucial components. As an example: Cycling 200km would require a lot of Work, regardless of the speed. Cycling at 45km/h would require a lot of Power, regardless of the Work done to achieve that speed. Cycling at 45km/h for 200km would require extreme amounts of both Work and Power. We can also calculate relative energy requirements, and use that to plan our training. A 2 hour ride at 150W would require the same amount of total energy transferred from foot to pedal as a 1 hour ride at 300W, even though these may have very different physiological requirements and effects on the body.

Training with Power

The main purpose of training with power should be to ensure optimal intensities are chosen in each interval of each workout, so that each component of the physiology is stressed in the correct manner, and you become the best cyclist you can be. To determine these specific intensities, the athlete needs to know what the limits are of their performance. Ideally, the athlete should perform regular performance tests at varying time intervals, so that they can get an understanding of what their individual strengths and weaknesses are. A performance curve, determined from more than one performance/time test, should be plotted so that there is an accurate estimate of the athlete’s 1-hour power. At MPG we use a 4 minute and 20 minute power to determine an accurate FTP (Functional Threshold Power) or CP60 (Critical Power over 60 minutes), which is the estimate of our best performance at 60 minutes. From this data we can get very accurate and relevant numbers which represent the various physiological zones. These values can be represented in a Performance/Duration curve.

It is critical to get the FTP estimate as close as possible. Some coaches calculate FTP by simply multiplying the cyclists 20 minute power by 0.95. This will only be useful for a relatively small percentage of the cycling population. In fact, it overestimates FTP/CP60 for the majority of cyclists. Cyclists who are strong and muscular, or cyclists with poor fatigue resistance will have real FTP/CP60 numbers which are lower than the 20 minute power x 0.95 estimate, whereas cyclists with excellent fatigue resistance will have real values which are closer to the 20 minute x 0.95 estimate. In order to accurately predict FTP, you need at least 2 data points so that a performance curve can be plotted; you need to see how much the cyclist is slowing down over time, rather than taking some random data point and making linear extrapolations from that. <

Once you have the correct FTP/CP60 number, in can be very useful in planning your training. We have already explored the relationship between Power, Work and Energy, so we can put that information to great effect. If you intend on becoming well trained for a long distance event, you can use your FTP to determine volume targets for your long rides. We know that well trained athletes can maintain higher percentages of their FTP for longer than athletes who are less trained.

Well trained Cyclists can maintain around 90% of FTP for cycling of 2-3 hours, 85% of FTP for races of 3-4 hours, 80% of FTP for races of 4-5 hours and 75% of FTP if the cycling race lasts longer than 5 hours. So, if a cyclist wants to be able to cycle for 4 hours at 80% of FTP/CP60, and their FTP/CP60 is 300W, they will be well trained if they can complete the race at 240W. We don’t want them to go out and simply ride at race pace for 4 hours in training. They need to build up their system to be able to tolerate those energy demands, as well as the muscular performance demands of achieving this goal, and we need to progress gradually. This example assumes even pacing, as in a time trial type event or solo effort.

If, for example, they are comfortable cycling at 180W, how long should they be able to ride at that power, before they have met the energy demands of a 4 hour race at 240W? 4 x 240W = 960. 960/180 = 5 hours 20. This will result in having enough endurance to finish the race, but it will not guarantee that the athlete can maintain the goal of 240W. Intervals of 240W or more would need to be incorporated into the long ride so that both metabolic and muscular components are well trained. From this basic example, you can see that by using the principles of Energy, Work and Power we have very useful tools at our disposal.

Generally, there should be 9 training intensities. It is important that all aspects of the physiology are stressed appropriately, so that the full endurance performance engine is developed optimally. It is also important to closely monitor the quantities of each zone within the training program. Doing too much too soon, particularly at effort levels at or above the FTP/CP60, without sufficient time given for physiological adaptation, is a recipe for illness and injury. It is far better to introduce these zones in smaller proportions into the training program initially, and build up the volume gradually. This will ensure that improvements are consistent and continue for many months.

An example of intensity and proportion of the training program are given below for a training week of 10 hours in total:

• Recovery – 50-60% of the FTP/CP60, 10% of the total volume = 1 hour
• Low Aerobic – 60-70% of the FTP/CP60, 20% of the total volume = 2 hours
• Mid Aerobic – 70-80% of the FTP/CP60, 25% of the total volume = 2 hours
• High Aerobic – 80-90% of the FTP/CP60, 25% of the total volume = 2 hours
• Sub Threshold – 90-100% of the FTP/CP60, 10% of the total volume - less than 1 hour
• Threshold – 100-110% of the FTP/CP60, less than 5% of the total volume - less than 42 minutes
• Above Threshold – 110-120% of the FTP/CP60, less than 3% of the total volume - less than 18 minutes
• Sub Maximal – 120-150% of the FTP/CP60, less than 2% of the total volume - less than 12 minutes
• Maximal - 250% of the FTP/CP60, less than 1% of the total volume - less than 6 minutes

As you can see, calculating all these zones and creating a training program that holds to these principles is a time consuming and arduous task, and as a result most coaches forego any of this specificity and guestimate times and efforts for their athletes. MyProgramGenerator.com does all these calculations for you, and so if you prefer to be specific and intentional about the precision of your training, then look no further.

Happy training!

Freddy Lampret