That is a Question more should be concerned with for general Health and Wellness!
What is your Metabolic Cost of Running, Cycling, Paddling, Rowing?
That is a Question you have NO choice but answer and address with your training program!
When you Improve your Performance in Endurance Sports, you have lowered your cost!
I ran a Mile as a Sophomore in High School in 4:34 I could run a mile in 4:34 in college at 85% of my Max Heart Rate. I lowered my cost and raised my Mile performance to 4:00 at 100%.
The best way to train this is RPT Reference point Training what Dr. Vigil calls Fractionalization.