One of the nice aspects of running with the Stryd is that every day you see how much power (in Watts) you have produced during your training or race. This means that automatically you will note whether you are making progress and whether your training is producing results. But how good or how bad is your running power actually? How can you compare your performance to that of others?
Calculate your Functional Threshold Power (FTP)
In the first place you have to correct for the environmental conditions (temperature, wind, air pressure, altitude), the distance and the course. The best way to do that is to calculate your FTP from your race time. You can do that with our calculator. The FTP is the correct measure for comparison with others, because it is corrected for the circumstances. It indicates what your real performance has been.
Compare your FTP to world-class level
Hans currently has an FTP of 4.3 Watt/kg and Ron has 3.6 Watt/kg. So Hans has a higher level than Ron, but how do they score compared to others?
In our books we have derived the table below for the FTP of runners of various levels.
This turns out to be a popular table among runners because you can compare your own performance with others. We have therefore called this the performance index.
Correct for your age
Of course, to make a fair comparison, you have to correct for the impact of age. We have derived the table below for the performance index at different ages. The first column indicates the maximum (100%) value for the relevant age category, i.e. the FTP at the level of the world best. The other columns are for the categories international level (90%), national level (80%), regional level (70%) and club runners (60%). Hans is 66 years old and therefore has a national level with his 4.3 Watt/kg. Ron is 62 years old and just reaches regional level with his 3.6 Watt/kg.
Our approach has been adopted internationally (unfortunately sometimes also wrong, we explain this below)
Our books are widely read, copied and quoted internationally. For example, American coach Steve Palladino has set up his own Palladino Power Project, in which he makes frequent use of and refers to . In a recent article on the internet, he presents an adapted version of our performance index table, see the table below. He did this for the new Strydv3, which incorporates the air resistance. Palladino has therefore added a percentage to our table in an attempt to take into account the air resistance. He motivates this with the statement that our table would be based on the old Strydv2 (without air resistance).
Unfortunately, Palladino made a fallacy in this approach. He is quite right that the power values of the Strydv3 are higher than those of the Strydv2 due to the influence of air resistance. However, our table was not based on the Strydv2, but on our universal running model as shown below.
In our running model, we already include the air resistance. Consequently, we have already taken into account the air resistance in deriving the table, so that the adjustment of Palladino unfortunately is an error!
In our book we have also shown that the maximum FTP of 6.4 Watt/kg is actually the maximum power that the human engine can deliver (without doping and in 2020). This value is equivalent to both the world records in athletics and the world best performances in cycling and other endurance sports (such as skating).
The Strydv2 measures the power for the Running resistance plus Climbing resistance (P = Pr + Pc). The Strydv3 was launched in mid-2019 and also measures the Air Resistance (P = Pr + Pa + Pc). The Strydv3 is therefore a more complete running power meter.
We also note that the measurement of the running resistance by the Strydv3 is correct on a hard surface. On a trail or cross with pieces of forest soil or loose sand, the running resistance is higher. The Stryd does not measure this, but you will notice it as you will lose time.
The maximum power of the human engine is 6.4 Watt /kg.
You can determine your performance index with our calculator and our tables.
Steve Palladino’s modified version unfortunately is based on a fallacy and should NOT be used.
If you would like to purchase The Secret of Running (or the German version, Das Geheimnis des Laufens, or the Italian version, Manuale completo della corsa) you can do so in our webshop.