Directly related to skills that a soldier must possess in war, jumping was not a separate Olympic event as it is today. Instead, it was only part of the pentathlon.
Unlike in the modern Olympics, jumpers used halteres, lead or stone weights used for jumping events. To increase jumping distance, the athlete held one of these telephone receivers or dumbbell shaped weights in each hand, ran and jumped, swinging the weights, and released the halteres behind him at the end of his jump. Halteres weighed between 1.6 to 4.6 kilograms, or 3.5 to 10.1 pounds. Pausanias describes the halteres as "half of a circle, not an exact circle but elliptical, and made so that the fingers pass through as they do through the handle of a shield.”
Athletes jumped into a pit approximately 50 feet long and landed with their feet together. Officials measured a jump from the bater, a fixed point on the side of the jumping pit and used a kanon, a wooden rod, to measure the distance of each athlete's jumps.
How is it so different to Modern Athletics?
In the Modern Olympics, if you did Long-Jump, you would definitely not jump naked! Also weights would not be used in the Modern Olympics.
A little bit about the Spectators
About 50,000 people could sit in the stadium. Away from the arena, most spectators had to find somewhere to pitch their tents or sleep rough, but important visitors and athletes had hotel rooms. It was hot and overcrowded, and the water supply was poor, at first not even a proper drinking fountain. This didn't stop people coming though! The Games ended with a feast. Lots of oxen were roasted in a giant barbecue. Traders came to do business, entertainers such as jugglers and acrobats performed, also politicians made speeches to the crowds.
This Greek amphora (jar) shows long jumping. The jumper holds lead or stone weights, to help him jump further. Pegs in the ground mark previous jumps.