Maybe it is not a too steep climb, but imagine that you are stunted Roman legionary (the average height of 160-170 cm), have on himself the whole set of weapons and equipment, where only one scutum (convex shield of line infantry) weighs approximately 10 kg., and also - gladius (sword), pilum (spear), casis (the helmet), lorica segmentata (armor) and etc. Total, including weapons, uniforms, supply of grub for three days - up to 48 kg. No wonder they were called mules of Marius for their endurance.
Gaius Marius (157-86 BC) - famous Roman consul general and reformer of the Roman army.