Tracking power at the Tour of California
By Dirk Friel, TrainingPeaks.com
There were plenty of power meters being used at this year’s Tour of California, largely because it offered a unique early season opportunity for riders to test themselves against some of the world’s best.
Indeed, four teams made racing with a power meter a very high priority at the eight-day California race, because this would be the best field the world would see prior to Paris-Nice. What better opportunity to start collecting crucial numbers?
The professional teams Predictor-Lotto (Belgium), T-Mobile (Germany) and Slipstream (USA) as well as the U.S. National Team each stressed the importance of racing with a powermeter to their athletes. Team coaches and doctors delight in the opportunity to collect early season data that would both quantify the exact demands of the race and paint a complete picture of each rider’s current fitness level.
During the Tour of California, I had the pleasure of working with the Predictor-Lotto team on a daily basis, downloading and analyzing power data at the end of each stage. I had already attended several pro team training camps in January on the island of Mallorca and that helped me gather some baseline data and then see just how far each had progressed by the time they reached San Francisco on the 18th of February.
During the Tour, I also had the approval from the Predictor-Lotto team to post two professional riders’ daily files for public review. Feel free to view data for Belgian Mario Aerts and Josep Jufre Pou of Spain.
World-wide data management
Some days you have to remind yourself just how cool some of this stuff is. For example, after each stage I would download the Power-Taps into CyclingPeaks’ WKO+ software and then synchronize the data up to each rider’s TrainingPeaks web account. By sending the data immediately to a secure account, team managers, doctors and personal trainers would have access to it immediately, no matter where they were in the world. For example, Predictor-Lotto director Hendrik Redant was even able to access training data for team members who were training back in Europe while he was in California.
We analyzed race files with WKO+ software, which allowed us not only to help dissect the individual stage demands, but also to develop future training sessions in an effort to help the rider improve specific abilities.
For example, we tracked maximum critical power (CP) values each day, which included maximum 60–minute (CP60), 20-minute (CP20) and five-minute (CP5) segments. It is hard to push the body to the maximum in training, so racing is the ultimate laboratory to collect a rider’s true personal best values. Tracking maximal CP60, CP20 and CP5 values provide an indication of where a rider’s threshold power and VO2Max power values exist. These are crucial when it comes to road racing.
The Solvang time trial – at 23km – served as an ideal venue to collect maximum critical power values. This TT saw only two riders break the 30-minute barrier. Remarkably, both Jufre Pou and Aerts opted to forego their disc wheels in favor of racing with a power meter to gain the data. In Jufre Pou’s case, that decision probably cost him a top-15 final classification, but in return, he now has data that can be used to help him objectively train for his major goal of the year, the Giro d’Italia.
Jufre Pou, who weighs 147 pounds, averaged 388 watts for 32-minutes. His maximum 10-minute value was an astonishing 400 watts. This is some very valuable data as he starts to prepare for the Giro since the Italian race has a 13km uphill time trial and a 42km flat time trial. He can now use this data to design specific, objective intervals to prepare him for both. The time trial data from California also reaffirms that Jufre Pou’s functional threshold power (FTP) is somewhere between 380-390 watts at the time of the Tour of California.
Another great stage to track critical power values was Stage3, which finished in San Jose. The race took the riders up the steep grades of Sierra Road with just 23 miles to go on the stage. Jufre Pou averaged 408 watts for 12- minutes on the climb, 441 watts for the first five minutes. To understand just how hard that is you need to relate it to body weight to see the power to weight ratio it would take for you to produce the same speed up the same climb.
Jufre Pou weighs 65kg so that translates to a power to weight ratio of 6.2 watts per kilogram for 12 minutes after three hard hours of racing.
Training Stress Score
I work with the professional teams to help them better monitor individual fitness levels and track training trends over time. By seeing historical data and comparing day-to-day physiological stress, training programs can be custom tailored with an eye on the past. Riders should know that peak form comes with very high fitness and very low fatigue. One way to track fitness and fatigue over time is to follow monitor Training Stress Scores.
The TSS represents a calculated number that takes into account the duration and intensityof a workout to arrive at a single score of the overall training load and physiological stress created by that session. One hour of functional threshold (as hard as you can go for one hour) = 100 Training Stress Score points.
So why not just track kilojoules? The benefit of tracking TSS points over kilojoules is that TSS points are relative to one’s threshold power. A kilojoule on the other hand is the energy it takes to produce watts over time, but does not take into account individual efficiencies, or lack thereof.
For example, think about how efficient it is for a professional like Michael Barry to push 200 watts as compared to a recreational rider of the same body weight. Michael is simply much more efficient and therefore his TSS score for an hour at 200 watts would be very low compared to a recreational rider. Michael’s one-hour ride at 200w may only produce 30 TSS points, whereas the recreational rider may be at a max effort for one hour at 200 watts and therefore produce a score of 100 TSS points. But if we tracked kilojoules they would have both produced the same value. This is not a very good measure especially as threshold power changes over time.
Which stage was the hardest? That depends
Stage6 to Santa Clarita proved to be Jufre Pou’s hardest day since he was in the 9-man breakaway and averaged 284 watts for more than three hours. He produced 276 TSS points, averaged exactly 400 watts for five minutes to bridge the gap to the breakaway and then rode 100-percent with his breakaway companions in the effort to stay away from the field. In analyzing his power file we found that he rode 39 segments of time which averaged at least 300w for more then 45 seconds in length within a 3.5 hour time span.
That represents some serious interval work!
Meanwhile, the rest of his Predictor-Lotto teammates were able to sit in the peloton and save their energy for the final sprint. Stage 6 was therefore the third hardest day for most of the team. We don’t have access to data for the Discovery team, which put in a huge effort chasing down the break. We have to imagine those numbers were impressive, as well.
For many of the Predictor-Lotto boys, it was stage4 to San Luis Obispo that proved to be the hardest day. Mario Aerts produced 298 TSS points because this was the longest stage at 140 miles.
Bike racing as you can tell is becoming more like Formula One car racing every day. Not only do the riders change equipment based on the daily weather forecast, but they along with their coaches are monitoring massive amounts of data in an effort to get a fraction of a percentage point faster. Most of the top riders and coaches are analyzing, monitoring and planning training and race data in unimaginable ways just five years ago.