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Fitness features, December 30, 2004
Power-based training Part II: Power to the coaches
Following our article on the use of power meters in training, Cyclingnews caught up with a few members of our fitness panel and other well-known coaches to get their perspective on using power meters and how their methods of coaching have changed in the last ten years since their introduction. Kristy Scrymgeour and Anthony Tan report on their responses.
Heiko Salzwedel, who is probably best known for his role as head road cycling coach at the Australian Institute of Sport during the early-to-mid 90s - the same time power meter systems were introduced at the academy - says the power meter virtually replaced heart rate-based training in terms of creating programs for his athletes. "Before I used the SRM system, kilometre and heart rate were the common parameter to design training programmes," he begins.
"That means, a 5km workload for the same programme varied from winter to summer, from headwind to tailwind and in different profiles and temperatures. Contrary, the prescribed training ranges with the power meter are precise and clear."
Cyclingnews Form & Fitness panel member Ric Stern, who was under the tutelage of Olympic and world pursuit champion Chris Boardman's coaches, Peter Keen and Dr Louis Passfield - both big proponents of power meters - at the start of his formal sports science education in 1995, says he was aware of the potential as soon as he started using them.
"As soon as I started beta testing the original Tune Power Tap hub, I understood the potential of the equipment for coaching purposes. The hub (or another power meter) could directly report to me, the coach, exactly how the athlete had trained on that particular day. By examining each file and comparing multiple files, I could see directly how athletes were responding to various training loads.
"In short, this changed the way I thought about coaching and gave me an added dimension to understand how the rider responded. This gave added meaning to the various comments riders made."
Eddie Monnier, another member of Cyclingnews' Form & Fitness panel, says that nowadays, almost every one of his athletes under his guidance uses a power meter. Monnier echoes Stern's remarks in that feedback on intensity is instantaneous and objective, unlike heart rate or perceived exertion. "It's changed the way I approach interval training with my athletes," he says.
Watts are where it's at
So, irrespective of other external factors, the all-important unit of measurement changed, while heart rate alone has became an increasingly unreliable measure of performance, as Cyclingnews panellist Ric Stern explains:
"The advantage with power output over HR [heart rate]", he says, "is that power is what you need to see increasing, whereas HR can vary at a given power output due to a multitude of factors, e.g., fatigue, cadence, temperature, altitude, hydration etc."
According to Heiko Salzwedel, these other factors, such as temperature, dehydration - even problems in the back of your mind - make the training, if prescribed solely with heart rate zones, to an unreliable guesswork. "[With the power meter], 10 minutes in a certain intensity zone are the same 10 minutes in summer as in winter, on the flat or in the mountains. Therefore, my training plans describe the time to be spent in certain intensity zones, categorised in watts," he says.
Exercise physiologist and head coach for Whole Athlete, Dario Fredrick, concurs, and explains the drawback of simply training off heart rate alone: "HR is affected by temperature, cadence, gradient and wind, while watts are watts regardless. Power is a real-time, direct measure of work as opposed to a highly variable, delayed physiological response. It is useful, however, to use both measurements in tandem, as we need to monitor the body's response to various workloads."
Stern adds that the athlete is now able to objectively quantify training loads, and ascertain the exact demands -the primary reason why top-level riders use power meters in training or in important lead-up races.
"I cannot tell with certainty whether or not they've improved unless they have a power meter," says Monnier. "If they average 300 watts for a 30-minute test and last time they tested at 280 watts, they've improved. Whereas if we looked only at heart rate or speed, we wouldn't really know because each is subject to many variables. For example, the athlete's average speed may be slower but perhaps there was more of a headwind than the prior test. And heart rate is subject to both internal and external influences. That's why the power information is so vital."
While watts are where it's at, Salzwedel points out that the power meter has not made the heart rate monitor redundant; instead, he uses heart rate to analyse the efficiency of the training and to monitor how the athlete copes with the accumulation of workload.
"For a coach, both power output as well as heart rate are important means to evaluate training," he says. "The physical parameter, watt, describes exactly how much power is required to do work within a certain time, while the heart rate indicates how well the athlete copes with stress.
"The power output determines how many muscle fibres are required to contract. In other words: the higher the workload, the more muscle fibres are involved. The heart reacts with adapting its pace according to the required amount of energy and the accumulated waste products. Heart rate does not correlate with performance; it indicates only how hard the supporting system is working. Therefore, power is a precise parameter to plan the quality of training, while heart rate is a good tool for analysis."
The advantage of introducing power zones becomes apparent when it comes to quality training at higher intensities and for race analysis. In conjunction with heart rate-based training/analysis, power output shows how athletes adapt to training and it helps to prevent overload.
Asked if used as a tool for a coach's subjects in training or as a way of monitoring athletes' training and analyzing their races, Fredrick says both: "Analyzing power files from training sessions to determine power/HR/cadence relationships, as well as seeing specific demands of races and what athletes are capable of in competition as compared to training."
Stern has used a variety of power meters since 1993 and has been collecting power output data ever since. "I like to think of it [the power meter] as an on-the-bike coach!" he says. "It'll advise you when you're putting out too much power, and conversely, will tell you when to get a shift on.
"When you're performing intervals - especially short efforts and also longer efforts - it's all too easy to start at too high a power output that is unsustainable. It takes a while for the effort to catch up with you metabolically, and by the time that it does it's too late - your power will have started decreasing (see figure below). With the power meter, you can put out an even-paced effort (if that is what is required of you), which you should be able to sustain to the end of the workload.
"By using a power meter when racing, you can also ascertain why you did well in that race," explains Stern. "It may have been that the race was easier than normal, or atmospheric conditions were better (leading to a personal best in a TT).
"For e.g., my PB for a 25-mile TT was recorded with a lower power output than my second best time, when one would think that this would be the other way around. As the course was the same one, the difference was due to a better day (in terms of atmospheric conditions, even though my fitness was worse on the day). Using the power meter, I could see that the power output for my PB was lower than my slightly slower (second-best) time. Without the power meter data, I would have assumed that my PB also yielded my best power output."
Monnier, however, isn't convinced of the effectiveness of power meters in race conditions apart from time trials. "A power meter is invaluable for training, monitoring and time-trial pacing. I do encourage my athletes to use their power meter during mass start races, too, but it's often very hard to draw any conclusions from race data," he says.
Raising the bar
Scientific training and the advent of power meters has, according to Stern, increased riders' fitness to a higher level, and also believes the use of power meters has been instrumental in raising the bar in cycling performances around the world.
Monnier agrees, and says the 'haves' are far better off than the 'have-nots'. "I think power meters and more scientific approaches have raised the bar for the whole peloton," he says. "With an increasing number of athletes rigorously preparing for target events, it is becoming more and more important to have a disciplined, scientific approach."
Salzwedel is equally certain about the power meter's impact in the number of history-making cycling performances on the world stage over the last 10 years, believing the teams pursuit to be a case-in-point. "The dramatic impact of training with power meters is clearly visible in the progression of world records in time trial events," says the former head coach of numerous record-breaking teams pursuit outfits.
"As you can exactly calculate how many watts you must produce to reach a certain time, say in the 4000m team pursuit, you can set the training goals accordingly. You can predict performance in competition much better, as the training data measured in watts reflect in a more precise way the quality of training."
"I believe that some athletes using power meters have risen to higher levels, as their goals are specifically orientated to increasing power," adds Stern. "With other power-training athletes, they've reached the same level, but done so at a faster and more efficient rate. By careful monitoring of the rider's power data, ineffective training can be gotten rid of."
Fredrick says it perhaps the most succinctly: "For training, emphasizing quality over quantity. Less volume with more focused time on the bike. Greater performance gains made over time by a wider range of athletes."
SRM vs. PowerTap vs. others
Not surprisingly, with his roots in the German cycling system, Salzwedel has used the SRM cranks and only the SRM cranks. "I only work with the SRM System from Uli Schoberer," he says. "The SRM Professional Road is the most precise and reliable tool of measuring power. It is small and lightweight, but robust and does not require too much maintenance. Contrary to other systems, if you have a puncture or you need to change your wheel, you can still measure your power."
Dario Fredrick is also of the SRM-ilk: "Most accurate, weatherproof, easy to calibrate, reasonable weight, good user display (power control), excellent analysis software."
"I've used all the commercially available power meters and some that aren't yet!" boasts Stern. "Out of the current crop of commercially available meters, the two that I use most are the PowerTap and the SRM. Both are excellent pieces of equipment. The SRM is excellent if you like to change wheels frequently (e.g., training wheels, TT wheels, etc), whilst the PowerTap is simplicity itself to use, making it very user-friendly, and is an excellent system for portability (it's a piece of cake to move it from your training bike to race bike etc). Both systems are accurate, with the PowerTap possibly edging the SRM in this department."
While the SRM Powermeter and PowerTap are the two leading brands, there are a number of alternatives. Eddie Monnier has used the SRM Powermeter, PowerTap and Ergomo, and believes the ability to be able gauge average power output 'on the fly' is the single-most important feature - which the Ergomo is unable to do. "The Ergomo does not have interval capability in the CPU, so you cannot check average power while interval training, which is a major drawback in my opinion," he says.
Another alternative is Polar's system, which measures power via chain tension. It requires no component changes, needs no regular calibration, is the cheapest powermeter on the market and works in conjunction with Polar's popular S700 series of heart rate monitors, also making it the only powermeter to include an altimeter.
As with any measuring system, each has its strengths and weaknesses, although it appears the SRM's only negative is cost (the SRM cranks are significantly more expensive) and the inability to swap easily between bikes. Conversely, with the unit mounted in the hub, the PowerTap provides this feature, but this advantage is also its disadvantage, in that wheel choice is restricted. Polar's system is certainly easier to use in this regard.