The average person can easily carry a pistol, a knife, two large calibre weapons, several first aid kits, grenades, and hundreds of rounds of ammo with no problem at all.
the average quake 2 marine can carry 2 shotguns, a blaster, a machine gun, a chain gun, a rocket launcher, a rail gun, a BFG, a hyperblaster, a grenade launcher, a rebreather, an environment suit, ammo, weapon upgrades, data discs, a severed head, security keys, wear armour and still run around like an athlete.