How Powerful Are The Pros?
Wednesday 9th August 2006 - Dr Jamie Pringle
How our home-grown riders compare to the pros
This year's Commonwealth Games saw excellent performances on the velodrome, the mountain bike course and the road. There were 54 medals available across the events, and UK riders won 19 (five gold) and Australia took 20 (nine gold); both a long way ahead of the five medal total of the next closest country, Canada.
I suspect that this domination of the competition may feed the general perception that British cycling is in a very healthy state ? Chris Hoy and Victoria Pendleton are now becoming household names.
I had a vested interest in the men's time trial, and although I was disappointed to see Michael Hutchinson just miss the podium, I was very pleased to see him have a good race and be in the mix with the best riders on the day. The winner, Nathan O'Neill, had a very good ride indeed ? we are talking about a quality time triallist. But I know what a lot of people were thinking ? would he or Michael have broken into the top 10 of a Tour de France, Olympic or Worlds time trial? Just how good are the home nation riders really?
It's a fair question, although one likely to go unanswered because never the twain shall meet. But if you read some of the forums and believe a few seemingly well-qualified commentators, you may have heard suggestions that George Hincapie, Sergei Gonchar, Levi Leipheimer or even Lance Armstrong would have put a healthy handful of minutes into this field. Well, I'll contend that is simply not possible, and I'll show you why, by using some swanky physiological mathematics.
GREAT DIVIDE
The gap of 15 seconds that Michael Hutchinson was shy of Commonwealth bronze equates to riding a tiny 0.5 per cent faster. For silver, Michael would have had to have ridden 2.1 per cent faster (64 seconds); and gold, 2.9 per cent faster (88 seconds). Racing at this sort of level requires a power output of between 400 and 440W.
Hutchinson rode with SRM power cranks on his bike, so we have an accurate power profile for this rolling course. The relationship between speed and power depends on complex aerodynamics, and it's not easy to make comparisons between different riders, but for a single rider it's consistent (and predictable) and we can calculate the exact change in power (and directly, aerobic fitness) a certain change in speed would require. For Michael to have ridden 0.5 per cent faster to claim bronze would have required 5W more, or just over 1 per cent more power.
The folks at Omega and USE provided Michael with probably the fastest bike set-up in the race, but 5W, albeit teasingly trifling, is equally agonising when you're operating right at your limits. In his hour-record trials we discovered that finding 5W more ? either gaining that from fitness, or from using different equipment ? was equivalent to adding a whole lap of a 250-metre track in an hour ? or pretty much the margin by which that record is broken.
That 1 per cent difference in power is actually much smaller than the 3 per cent day-to-day variation in physiological fitness we normally expect in a human performer ? a variation that sometimes falls your way ? or not. However, we shouldn't entertain any ideas that the top step of the podium was a possibility had our man had his fabled 'float day'. The cubic nature of the power-speed relationship means that going 2.9 per cent faster in time to win gold would have required a huge 35W, or 9 per cent more power, which was unlikely to happen!
So, to go just a little faster at this level of competition requires a large increase in power and
fitness ? it becomes more and more physically and physiologically difficult to find gains in speed as we approach the upper limits.
FASTER AND HARDER
For a typical male tester to break the hour for 25 miles would require him to sustain about 250W of power (around 230 to 280W depending on body size, position on the bike and equipment, although I've seen as little as 200W in a pocket-rocket female national champ and well over 320W in a six-foot male). For our rider to shave 5 minutes off this time (ie 55 minutes and riding at 27.3mph) raises the required power by 70W and up to a 320W average. At a body weight of 75kg, that's 4.3W/kg ? about the standard of a first or second-category male rider.
To take a further five minutes off the time and break the impressive 50-minute mark (ie to travel at 30mph) the required power rises a further 100W and goes up to 420W. This would mean being able to be in the mix at the National Championships and at 5.6W/kg is approaching the standard of the top-level professional riders.
When Lance Armstrong made noises of attacking the Hour record at the end of his career, there were suggestions of him being able to smash the record and being able to sustain 'about 500W'. That figure was even suggested in a peer-reviewed scientific journal (Heil, 2005, Eur. J. Appl. Physiol., 93: 547-54) and seemed to be accepted as 'truth' from there on in.
But it's nonsense. The highest values we could expect in a world record holder would be about 6.4W/kg over an hour-long race in males and 5.4 W/kg in females. I do not believe that Armstrong could sustain any more than 6.4W/kg over the race, and at 72kg that equates to a more realistic but still hugely impressive 460W.
UNMATCHABLE
One of the single most impressive rides I've seen in time trialling was Armstrong's second place in the prologue of the 2005 Tour de France. To beat his main rival Jan Ullrich by 66 seconds in a 21-minute time trial is a colossal gap. Both riders were on the same stretch of road and only one minute separated them as they left the start house. Armstrong put a minute into all his major rivals, so it can't be claimed that Ullrich was going easy and it's unlikely that everyone was having a bad day at the office.
These riders will be sustaining a power output between 450 to 475W (6 to 6.6W/kg). At speeds of 50kph-plus and in a race of this duration, each 10 seconds faster requires about 8W more power, so at face value, this means a difference between Armstrong's and Ullrich's sustainable power of about 50W! Could he really have been a whole 10 per cent fitter than all his major competitors? I think not ? the difference in their physiological capabilities is probably not as great as that time margin suggests.
That is, I suspect Armstrong has optimised every single aspect of his equipment and body position to generate more speed for his power compared to Ullrich. Little gains in speed here and there really do add up ? optimising the weave and cut of the rider's skinsuit can save up to a second each kilometre ? that's perhaps 20 seconds of the margin between these two.
Last year, Armstrong's physiologist Professor Ed Coyle, gave us an insight into the progression of fitness across Armstrong's career (Coyle 2005, J. Appl. Physiol.; 98: 2191-6). Coyle reported VO2 max values ranging from 5.5 to 6L/min which is 76 to 83mL/kg/min when this value is expressed relative to the rider's body weight. Although no figures are reported for Armstrong at the peak of his powers, Coyle commented that he would expect a VO2 max of 6.1L/min or 85mL/kg/min at the time of his Tour wins.
But I contend even that has to be a considerable underestimate of Armstrong's capacity, as Coyle's numbers don't add up; in every test conducted in the previous two years, Hutchinson has generated VO2 max values in excess of this.
BEYOND A PUTATIVE PEAK
Endurance performance cannot be explained in terms of VO2 max alone. Just as important is the individual's ability to sustain a high percentage of this maximum capacity. Furthermore, of all the components of his impressive physiological make-up, Armstrong had a good ability to convert the metabolic capacity of his heart, lungs and muscles into mechanical power with little wasted effort.
This seems to be related to the volume of training built-up over many years. For example, research in world-class Spanish professionals found they could generate up to 20 to 40W more power for the same oxygen cost compared to their amateur counterparts (Lucia et al., 2002, Med. Sci. Sports Exerc., 34: 2079-84). However, Armstrong and Hutchinson (and presumably Ullrich) have broadly similar efficiency scores, so this can only explain a small part of their differences.
I've suggested here that Armstrong can find some 20-60W more than our top Commonwealth riders (and most of his competitors in that 2005 prologue). We also know that every watt requires oxygen to produce and, even with Armstrong's efficiency, this extra output will still 'cost' him around 0.6L/min of VO2.
This suggests that Armstrong would have required a VO2 max of about 6.7 L/min at Grand Tour fitness. At his racing weight this is about 93mL/kg/min, which not only exceeds the highest values ever published for cyclists, but nudges firmly against the ceiling of physiological ability as we know it. Increases beyond this are beyond the highest capacity of the heart, lungs and circulation of a normal man of equivalent size. It is unlikely we'll see anything like this again any time soon.
So how would Armstrong, in peak condition, have fared at the Commonwealth Games? The 460W upper limit suggested above for an hour-long effort is about 10 to 15 per cent higher than our top domestic pro and, assuming similar aerodynamics, this would have equated to 50.3kph, or a time of 47-42, which is 50 seconds faster than gold medallist Nathan O'Neill.
Jamie Pringle is a sports scientist lecturing at Brighton University.
