Talkback: What's the difference between average power and normalised power on the bike?
I'm not sure I really understand this explanation. I thought normalised power was basically an average power calculation which excludes any periods where the power output was zero, i.e. coasting downhill. Am I wrong?
David, sadly yes. NP takes the average power then adjusts it for the peaks and troughs of say, going up or down hill. But it does this taking into account the physiological cost to your body.
So if you average 150W for the ride, but go uphill at 200W there is a physiological cost, if you were to go up at 250W the increase in cost is greater than twice the increase to 200W. Increasing power has a disproportionate physiological cost. NP takes this into account. As you go downhill and the power drops below average the physiological cost reduction isn't as great as the same increase by going above average. NP also takes this into account. By its nature physiological cost is more of an estimate than a precise calculation.
Thats my understanding anyway.