The long jump was not practiced as a separate event, but was part of the pentathlon. The jumper landed, just as today, in a sandpit. It was created by raking the hard sand of the stadion over a length of a bit more than fifteen meters.
A major difference with the long jump today is that the Greeks held jumping weights or 'halters' of 1,5 to 2 kg in each hand. Thanks to these halters the athletes jumped further and landed more steadily. Experiments have shown that, with the modern jumping technique, the weighths reduce the length of the jump and hinder the run-up. Clearly the Greeks practiced a standing long jump, with their two feet together, in which case the halters do offer an advantage. The take-off is more powerful when swinging the halters forwards. Swinging the weights backwards produces a counterweight while landing, to avoid falling forwards.
A second problem is the length of the jump. Phayllos of Kroton, one of the greatest ancient long jumpers, jumped 55 feet (16,3 m) and because most sand pits were only about 15 m long, he landed outsite the pit. As a trained athlete cannot reach much more than three meter in a single standing jump, the Greek long jump must have been multiple. They probably made five jumps in a row - the number five being symbolic for the pentathlon -, each time a standing jump with both feet together, so not like in the modern "hop, step and jump". The landing position of the first jump was the starting position of the second. In a modern experiment well-trained athletes, who practiced this technique for eight weeks, did indeed make a fivefold standing long jump of about 15 m. As a multiple jump asks a lot of coordination, jumping was always accompanied by flute music.