1. Killer quads
Hauling a pack builds stronger muscles, especially glutes, quads, hamstrings, calves, and shoulders.
2. Muscles that don't quit
Carrying your pack over long distances endows these same muscles with added endurance.
3. Beefier muscle fibers
High intensity hiking bulks up muscle fibers, especially the faster ones involved in power and strength.
4. Extra energy
Sustained hiking bolsters your muscle cells' mitochondria-organelles that fuel the cells. The upshot? Your muscles can crank out more work.
5. The pink bunny effect
Hiking ups your aerobic endurance so you can climb on and on and on....
6. Less burn
Long days on the trail train your muscles to work harder with less lactic acid buildup.
7. More heart
Taxing your heart with hikes strengthens this muscle so it can pump more blood with each beat.
8. Fuel efficiency
Long, steady backpacking teaches your body to use oxygen more efficiently so you can hike harder without extra effort.
9. More juice
Aerobic exercise expands your blood volume so it can carry more oxygen.
10. Serious circulation
All that hiking increases the number of capillaries in your body, and thus the blood supply available to your muscles.