Polish Jews are forced to hold heavy logs while squatting. This is a classic form of torture and torment the world over. Not terribly taxing at first, holding the object becomes more and more difficult with every passing minute. After only a short while, the arm muscles begin to ache and shake. Finally, the muscles simply give out. Not a big deal when it's a contest between friends. A much bigger deal when you continue to live only as long as you can keep the object raised.
A6M zero fighter at rest on the Akagi taken in November 1941 in Hitokappu Bay in the Kuriles. This is shortly before the Akagi departed with the rest of the Japanese fleet to attack Pearl Harbor, this is shortly after the fighters had finished preparatory training at Misawa Air Bases Lake Ogawara.
Sunken WWI U-Boats a Bonanza for Historians: Explorers find dozens of WWI U-Boats off United Kingdom coast - http://www.warhistoryonline.com/war-articles/sunken-wwi-u-boats-a-bonanza-for-historians-explorers-find-dozens-of-wwi-u-boats-off-united-kingdom-coast.html