German scientists have collected data from six professional road cyclist´s during a multi stage race. The riders used the SRM system to measure power outputs and heart rate monitors to record heart rates. This study got my attention, because it shows the benefits of using a power meter in the races instead of just a heart rate monitor. It was published in Medicine and Science in Sports and Exercise, January 2006. Before I start advertising more for using a power meter system, I will tell you a little about the study setup.

Before the stage race the six riders performed an incremental cycling test in the laboratory. Peak power output, power output, and heart rate at the lactate threshold and at a lactate increase of 1mM above the lactate threshold were assessed. Based on the test results there were made 3 different intensity zones for both heart rate and power output. Zone 1 was below LT, zone 2 was LT to LT+1mM and finally zone 3 was above LT +1mM. After the testing session the riders were ready to compete in the stage race.

The scientists analyzed the time spent in the three target zones during the 6 stages. There were five mass-starts where the riders averaged 220 Watts and one uphill time trial with an average power output at 392 Watts. This is not breaking news for experienced power meter users. In an uphill time trial riders prefer to ride with a slower cadence and are therefore able to maintain a higher average power output and they have to go fast all the time which also adds Watts to the average power output. In the mass-starts the heart rate monitors over-estimated the time spent in Zone 2, and I am not surprised at all. The heart rate monitors recorded that the riders spent 38% vs. 14% recorded with the power monitor. Heart rate monitors are still valuable, but it is important to know the physiology behind to understand how it works. There is a delay in the heart rate due to oxygen deficit or repayment of oxygen debt. A professional cycling race is either slow or very fast, there is almost nothing in between. But when they ride this stop and go way, the average heart rate will be somewhere in between, in this case this will say Zone 2. This could lead to the wrong conclusion that training in heart rate target zone 2 is optimal for preparation to stage races. Listening to the power meter makes more sense to me, since it tells me instantly what the power output is and therefore gives a much more precise description of the effort.

Reference:
Vogt S, Heinrich L, Schumacher YO, Blum A, Roecker K, Dickhuth HH, Schmid A.
Power output during stage racing in professional road cycling.
Med Sci Sports Exerc. 2006 Jan;38(1):147-51.

My theory is that the intelligent rider will achieve more success in his cycling career than his opponents. It is already concluded that it is possible to improve performance through better training principles, better materials and proper nutrition. The intelligent rider uses these conclusions to become an even better rider. One of the places to get more information about training planning, materials and nutrition is on this website. I think that one of the most interesting topics for cyclists and triathletes right now is wattage training. As a cycling coach I can see so many logical ways to use a power meter, that I can only recommend that you afford one.

This blog is updated with news about physiology, exercise and reviews. There is an introduction on how to integrate a power meter like SRM, Ergomo or Powertap in your training. Like the heart rate monitor was the best way to monitor training in the last decade, power meter training is the gold standard now. Power meters are getting affordable, but they are still very expensive. Therefore I suggest you spend some time studying how to get the most out of your investment.

Power meters are getting very popular especially among professionals. It is very easy for them to measure their effort to a cycling coach. As a cycling coach myself I know how difficult it can be to give advices to riders. With the development of power meters I got a very powerful tool to optimize their training. Now it is much easier to discover weaknesses and help my riders to improve. When I make training plans for my riders I can make specific intervals made for their actual level. And the best of it is, that it is much easier for them to ride the intervals as described because the watts are not influenced by the wind, course or equipment.

Power meters are very expensive and for many people it is a big decision to buy one. Polar offers one of the cheapest power measurement systems on the market, so it was interesting for me to see how it performed compared to the much more expensive SRM crank system. SRM crank system uses torque and angular velocity to measure power output, while Polar uses the vibration and speed of the chain to calculate power output.

British scientists made a study with 12 trained men who made 12 all-out efforts separated with short recovery periods. This study setup is very demanding for the power meters, since the stress on the bike is very high. The purpose of the study was to compare the agreement between these two different systems. The results were published in Journal of Sports Science, August 2006.

Polar underestimates power output

The main finding was that Polar underestimated the power output and did not agree with the power output from SRM. One of the great problems with the Polar was that it was greatly influenced by chain vibration and sampling rates.

These findings agree with the experiences I have been told about Polar. If you ride on cobble stones it is not reliable at all and it is necessary to change chain often. It is obvious that you can not get a precise system like SRM and only pay 1/10. For me Polar offers a cheap entry level for riders who would like to explore power outputs without spending all their money. I believe that you can make analyzes of races and get a good feeling of how races are. But I am not sure, that Polar is good enough for pacing in intervals. Maybe I should go try one?!

Reference:
Hurst HT, Atkins S. Agreement between polar and SRM mobile ergometer systems during laboratory-based high-intensity, intermittent cycling activity.
J Sports Sci. 2006 Aug;24(8):863-8.