Re: Power Meters and Pedaling Effectiveness
Originally Posted by RapDaddyo
But, I am a bit surprised to learn that HR is not a predictor of fatigue if it is a proxy for effort and if greater effort leads to earlier fatigue. I understand what you are saying and accept it, but I just don't understand why.
HR varies for many reasons, but tends to increase as you cycle at a higher power output, and decrease as you cycle at a lower power output. However, HR is only one aspect and it is cardiac output that is a better measure (CO being the product of stroke volume and heart rate).
HR will also vary due to other factors, as you have found out, by riding at a constant power and varying the cadence your HR will be different but performance isn't. Caffeine will raise HR, and temperature will decrease or raise it a given work rate at low and high temperatures respectively. Additionally, altitude, dehydration and anxiety can all cause it to fluctuate at a given power, as can fatigue, state of training, illness, and certain foods. Topographical conditions can also affect it.
I find that HR can vary dramatically under given workrates making it impossible to decipher what it may mean (other than the speed of your heart). What's important is whether you can generate the power that you need over the duration of the session irrespective of HR.