In the Royal Marines the final commando test is the infamous 30 miler across Dartmoor.

Wearing basic boots, webbing, rucksack and carrying a rifle totalling 45lbs in weight – recruits have to go up and down hills, cross streams, swamps and moors in under 8 hours to earn their coveted green beret.
Blisters! Because it’s such hard terrain carrying over 3 stones on your back it’s the equivalent to running two normal flat marathons back to back.
Throughout the 32 weeks of the longest and hardest infantry training in the world the furthest that any recruit will run is 12 miles.
The rest is made up of 40 minute intense circuit training sessions that work the whole body and increase your VO2 max / endurance and also some fast short runs (1.5 miles flat out).
It sounds far fetched but it’s a tried and tested winning formula designed by sport professors at Loughborough University.
So that goes to show that you don’t need to spend hours and hours long slow boring jogging on the roads to increase your fitness, if you work hard and push yourself really hard every now and again at boot camp then that will do the job too!