More than likely you have heard people say that riding at more than 6 watts per kilo is superhuman, impossible, unachievable, and finally; Doping. I find it a little peculiar.
They give anecdotal reasons based more on the fact that not many people have achieved this, than actual biology. It’s a lot like a conspiracy theorist saying that the moon landing didn’t take place. It did, it’s just a little hard for some people to comprehend.
Dr Andy Coggan gives us a scientific run down on the theoretical limits of human performance in this blog posted to Cycling News; “The Clinic”. Andy Coggan is the man that gave us Normalised power and Training Stress Score (TSS). Its safe to say his analytical skills are on point. Coggan puts the theoretical limits at approximately 9wkg for 1 hr by using the highest efficiency, Vo2 max and aerobic capacities of all athletes in the literature rolled into 1 man (or woman). Read this here.
So if we haven't hit the limits of human performance what's stopping us? As an athlete, and from an athlete's point of view; its really hard to do that much training.
For a 75kg guy to have a threshold of 6wkg (450w), you will need to do all your base kms, Endurance zone training (56% to 75% ftp), at an average speed of between of 35.3kmh to 39.3kmh. Anything easier than riding at 35kmh is recovery and not improving your fitness (this includes sitting on the wheel).
It becomes difficult to find training partners to ride at these speeds, not to mention unsafe. Riding long climbs is the best way to reduce your speed and increase the effectiveness of your training. If you don’t live in an area with 1 to 2hr climbs you will struggle to hit these training zones and performance will suffer. This is exact reason why all the top athletes permanently live in the mountains. Furthermore, the mental aspects of training alone also take a toll. There are very few people on the planet that can keep up with you. This is not a transient solitude either, it takes years of dedication to build a big aerobic capacity. There seems to be a self limiting cycle where the fitter you get, the harder it is to sustainably hit your training zones and keep improving. From a molecular biology, standpoint there is very little to limit adaptation if the appropriate stimulus is applied.
It begins to seem that the limits of performance are more Practical limits than Physiological ones. And with all practical problems, just like going to the moon, if you spend enough time thinking about it you will find an answer. The problem is simple; to achieve peak performance you need to be hitting specific metabolic and physiologic targets, however to exist in the real world you need to satisfy the human aspects of life. Athletes aren’t robots, real world constraints apply to them.
The biggest difference between the successful teams and the unsuccessful teams is the execution of the training programs. It's not that elite teams are doing super secret intervals sets but rather they have procedures and actions put in place to increase the probability of success and to reduce the mental cost required for peak performance and training.
Human Physiology hasn’t changed in the last 60 years, so what makes big budget teams succeed is their ability to simply reduce the effort required for excellence. Using a familiar pillow, having a motorbike follow coach, holding training camps in challenging places with great weather, having fun staff and removing mental distractions, all contribute to the training ability of a rider.
Simply put, ergo sessions in a dark East Berlin gym doesn’t cut it anymore. Now it's summer in Bright or winter in Majorca where the terrain is so tough that by simply riding your bike you will hit peak performance. To paraphrase Ian Mckenzie (Australia’s most successful track coach) and Aristotle;
The goal here is to make excellence a habit, not something that we do, but something that we are.
In Summary, the biological limit is hard to hit on a practical level, yet we are slowly making it easier. So keep a close eye on your training habits in the future. What simple changes can you make to remove the barriers to excellence?
To pull speed from power is a little more difficult than going the other way.
Firstly we know;
P = CdA*0.5*rho*v^3 + Crr*m*g*v
That makes v(P) a bit more complicated, but it's a cubic polynomial with one single real root:
a = P/(rho*CdA)
b = 2*Crr*m*g/(3*rho*CdA)
v = ( a + sqrt( b^3 + a^2) )^(1/3) + ( a - sqrt( b^3 + a^2 ) )^(1/3)
Thanks to Andy Froncioni from Alpha Mantis, the smartest guys in Aerodynamics, for providing the above equation.