That’s true if you keep exercising at the same absolute output, but that’s not what you’ll naturally do. Your speedometer is how hard it feels. What getting f

That’s true if you keep exercising at the same absolute output, but that’s not what you’ll naturally do. Your speedometer is how hard it feels. What getting fitter enables you to do is increase the output without it feeling harder, either through increased duration or increased speed/power/etc. Be wary of using heart rate as an indicator of this - it varies massively between people, and approximating energy output from it is not much better than using math.rand(). If you’re training to the same heart rate but your speed is going up, you can say you’re improving, but you can’t apply an absolute measure to it with any accuracy.