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Monday, July 09, 2012

The Tour in the mountains: Analysis & discussion

The Tour hits the mountains: Power output thoughts

The 2012 Tour de France has reached its first rest day, and with it a chance to catch our breath after a frantic few days that have taken the peloton into the mountains, then to a time-trial, via a press conference which generated just as much interest as either of the Tour's first "shake-up" stages.  If it's the mountains, then it must mean power output analysis, and so below, I look at some of the limited data from Saturday's mountain finish, and ask whether it flags anything "suspicious"?

First, the press conference.  In case you missed it, it featured Bradley Wiggins, leader of the Tour de France, fielding a question about doping accusations from skeptics on social media with the following answer:
“I say they’re just fucking wankers,” Wiggins said. “I cannot be doing with people like that. It justifies their own bone idleness because they can’t imagine applying themselves to do anything in their lives.
“It’s easy for them to sit under a pseudonym on Twitter and write that sort of shit,” Wiggins added, “rather than get off their own arses in their own lives and apply themselves and work hard at something and achieve something. And that’s ultimately what counts. C**ts.”  (Did I mention that this post is rated R for profanity?)
Many have commented on this already, and far more eloquently than I can.  The best of those, and well worth the 5 minutes it will take to read, is this by Joe Lindsey, who addresses all the key points.  The bottom line is that cycling's history puts its current champions squarely into the doping spotlight, and so this is a question that owes its origins to fifty years of deception.  Given this, a more nuanced response would be welcome, and a stronger anti-doping stance celebrated by those who share Wiggins' apparent frustration with doping (and here I exclude the snipers who will never be satisfied, but they're really not worth spending energy on)

To understand the perception of cycling from its fans, there is no better expression than this, written on a forum by a fan, and it says what I think many who follow the sport closely are feeling.

Some thoughts before getting onto power outputs.  First, I would start by highlighting that I would like to believe everyone wants the same thing - a drug-free sport.  I think Wiggins (based on his and Sky's history), those asking the question and those who are now a little concerned and perplexed by his answer share a common desire.  And given that desire, they come to the debate WANTING to believe.  The fans who matter (again, I exclude the outright snipers who just want to tear things down) want desperately to believe that after years of false flats, we've finally reached the end of the hard slog uphill and can enjoy a free ride into a doping-free sport.

Let's face it,  for at least 15 to 20 years, cycling has made fools of its fans.  Just go back and look at the top 5 of the last 15 Tours de France and allow yourself to reminiscence about the excitement you felt watching the race, discovering a new star, cheering your rider to victory, only to later discover the deceit.  I know I have.

Therefore, it is not unreasonable for people to be skeptical, particularly when every one of those champions has vehemently protested their innocence before their fall.  So when the latest champion (and a man who after today's TT looks more likely than ever to be a huge champion) doesn't give the response they crave, a negative reaction is expected, however unfair it may be for us to want a specific anti-doping response (another debate).

Having said that, I can also appreciate that to a rider who has reached the summit of the sport without doping (let's assume this to be true here), and who has invested so much time and effort into that dream, the nagging questions will be frustrating, even angering.  So in the midst of "battle", perhaps one should make allowances for emotional responses.

Here's the thing though - that anger and emotion should surely be channeled and directed towards the people responsible for the question in the first place - the dopers.  The "irksome, annoying question" that triggered Wiggins wrath surely owes its origin to the actions and deceit of previous generations.  Someone asks it in 2012, sure, but the question is planted in the 90s and 2000s by the generations of Mr 60%, Pantani, Ullrich, Armstrong, Landis.  Wiggins has famously shown his contempt for dopers before, including once calling Christophe Moreni  an "idiot" for the doping offense that saw Wiggins' Cofidis team withdraw from the Tour in 2007.

That is the type of response fans applaud - they want their riders to share their anger, to condemn cheating.  They cannot understand why a clean rider, who loses out to dopers, would not join them in the fight AGAINST doping, rather than becoming a passive observer (and 'victim') of a dishonest culture (as an aside, the psychology of silence among clean riders in the peloton would make a fascinating thesis).  Can you blame them?

But for too long, cycling's champions have been perceived to be leaning more towards sympathy to dopers than condemnation.  Wiggins' response is viewed by those people as being yet another example of this.  Further, Sky have crafted themselves as a team that prides itself on its anti-doping stance, and their vocal attitude against doping has rightly been hailed as leading the way into a new era for the sport.

So when their star rider, the man who is identified as a custodian of the sport by virtue of the yellow jersey he wears, suddenly turns that anger and wrath against the fans, I can appreciate the disappointment.  This is the greatest opportunity for clean riders to show the world that the sport has moved on, and swinging in the opposite direction, against the detractors, only fuels their skepticism and ultimately, invites more of the same doubt.

It doesn't help that Sky hasn't entirely broken ties with all doping baggage, as they still have ties to doctors known to have worked in teams with doping tolerance.  This doesn't mean they are doping, and even the doctors can change, but perception is reality, and people who view the sport from outside, who dream of a dope-free Tour, need a stronger reassurance than this.

In any event, more time may be required, and hopefully, anti-doping stance will not be discoloured by a yellow jersey.

Now, onto the power outputs.

6.2 W/kg for a top 10, 6.5 W/kg for the lead group

So, unfortunately, we have a scarcity of top rider data, as is often the case, but we do have Jani Brajkovic's SRM file to play with.  I've taken it from the TrainingPeaks Tour analysis site, and zoomed in on the relevant section, the Les Planche des Belles Filles.

The climb took Brajkovic 17 minutes to complete, and he lost 46 seconds on the stage winners (16:15 for the fastest time of the day).  His power output was reported as 351W, which gives him 5.8 W/kg (remember that relative power, expressed to body weight, is crucial for climbing, and it also allows comparison to other riders).

Note that there is about a minute's worth of missing data in the file, in the first quarter.  Jani actually tweeted me himself to point this out, and obviously some technical gremlins affected the SRM.  If one attempts to "normalize" these sections, and push them up towards the range of 400W that the power was at the time, then the average power output jumps from 351W to about 375W, and the relative power output is around 6.2 W/kg.

So, in terms of what that means for Wiggins and co at the front of the stage, it predicts about 6.4 to 6.5 W/kg.  Over 16 minutes, that's not at all unreasonable.  To give you some context, calculations of climbing power output in the Tour de France in the 1990s and 2000s often estimated that top riders maintained power outputs of 6.4 to 6.5W/kg on the Tour's HC climbs, most of which take over 40 minutes to climb.  So in other words, there was an era where the best riders were maintaining similar power outputs to what we saw on Saturday, for three times the duration.  Put differently, all those riders would probably have been a minute clear of this current generation on this climb...

Another point is the physiological implications of this performance.  I try to explain this every year, but every year it seems to invite the (obvious) criticism, of which I'm well aware, that assumptions have to be made.  Every year, I try to explain that if you control the assumptions, and make sure you always take "best case scenarios", you get a very clear and accurate picture of the physiological requirements behind a performance.  So we'll try this again...

I've written before that I believe a sustained power output of above about 6.1 W/kg on the longer (40 min or more) climbs is not physiologically 'plausible'.  I know that this is a view that Aldo Sassi shared (independently, I might add), and the reason for it is that to produce that kind of work, there are physiological requirements.  Think of them as specifications in a car, and unless you have a certain engine, you can't achieve certain speeds.  In cycling terms, the performances of 6.2 W/kg and higher simply cannot be met by any plausible combination of VO2max, cycling efficiency and thresholds.  I describe this theory and the assumptions in this post from back in 2010.

Back to the 2012 race, the assumptions one might make for a 17 min climb are that a rider with efficiency 23% (high case assumption) can sustain 90% - 95% of maximal intensity for this short duration. Then, you can estimate that riding at 6.2W/kg (again, this is Brajkovic), the VO2 on the climb will be 77 ml/kg/min.  Given the 90-95% of max estimate, this rider has a predicted VO2max between 81 ml/kg/min and 85 ml/kg/min  (I realise there are 'errors' in the assumption, but I compare across generations to illustrate a point)

If you take lower case assumptions (efficiency of 24%, which I think is probably a more reasonable assumption), then the estimated VO2max falls to between 77 and 81 ml/kg/min.

Obviously, you can infer from these numbers what the implications are for the top 5 on the day, and you'll see that they're not too different.  You're predicting physiology that says that the world's best cyclists have a VO2max of 85 to 87 ml/kg/min, that they're 23% efficient, and riding at 90% of maximum.  Or, they could be 24% efficient with a VO2max of 81 ml/kg/min.  That is, on paper, normal physiology for the best cyclists in the world in peak condition.

The "abnormal" physiology of years gone by came from guys who were sustaining 6.4W/kg for 45 minutes.  That points to a human that has a VO2max of 97 ml/kg/min on the bike, or an efficiency of  28%, or can sustain 95% of max for 45 min at the end of five hours of racing.  That just doesn't happen.

There's a risk of running away with physiological implications here.  Let's simplify it into the obvious metrics - power and time.  The difference between the current era and previous eras is startling.  In the last four years, none of the Tour's decisive HC climbs have been done at greater than 6 W/kg.  Even the Contador-Schleck showdown on the Tormalet, with the Tour title at stake, was ridden at 5.9 W/kg.  

The graph below was put together by Alex Simmons, and it shows the time on the famous Alp d'Huez climb as a function of power output.  There's a lot of data there but slide your finger across from a time of 38:30.  That's the kind of performance (or faster) we saw in the previous generation.  Then consider the more recent times - Frank Schleck did 40:46 in 2006, the first time in 12 years they didn't break 40.  The best performances in the last 3 years are all slower than 41 minutes.  That fits well with what I've added to the graph in blue and yellow - those are the equivalent performances to two climbs in the 2010 Tour, where riders simply don't get above 6W/kg anymore.  Not even once, let alone repeatedly during the race, as they once did.

Chris Froome, when coming second in the 2011 Vuelta TT (47km) rode at 5.8 W/kg for 55 minutes.  That's likely to be close to what he and Wiggins produced in the Tour today, and is yet another indication of where the "ceiling" for that duration of effort lies.

So that's what we're all getting at when we say the Tour is getting slower.  It is, and it's a good sign, because it brings everything back into the realm of expected physiology.

Now, an important disclaimer.  None of this disproves doping, and none of this proves doping either.  When a rider produces performances that have "alien" physiology implications, it's a strong flag for doping (I'm gratified to read that cycling's governing bodies are actually looking at this approach now). But when the physiology is "normal" or at least, not suspicious, then it doesn't necessarily vindicate the rider.  Why?  Because doping helps with far more than on-the-day performances - it also aids recovery and thus enables consistency. 

So we can't rule anything out this way.  All I will say, and I'm very confident in saying this, is that what we saw on the slopes of Les Planche des Belles Filles did not have me thinking "That's just not right, there's something not adding up".  It adds up.  It's exactly what you'd expect, just as I expect that when we do hit the longer HC climbs later this week, we'll see the top men ride at 5.9 to 6 W/kg, just as they have done for the last three years.

It will be fascinating to see what develops in the high Alps and Pyrenees over the next two weeks.  Hopefully, we'll have some data to chat about.  And a press conference or two!