You're gonna laugh your azzz off when you read this But there is an old saying in the hiking community that says that one should never hike faster than one can sing >it has to do with your abilty to breathe properly >so the question then becomes what do you sing ?
As a solo hiker I am notorious for singing old Broadway show tunes and 50's doo -wop at the the top of my lungs while hiking
Two reasons why
1) These songs were written for people who can actually sing
2) If you can hike uphill with a 45 lb pack on while singing "Why do fools fall in love " at the top of your lungs then you're in decent shape
Try it, it's hard to do.