Last Lap:Be thankful the marathon doesn't finish in another city. Frank McNallyexplains.

The enduring popularity of the marathon is all the more remarkable considering the event's origins, in 490BC. As everyone must know by now, the original marathon runner - Pheidippides - gave a chilling resonance to the term "finishing-line" by dropping dead there. This was not only unfortunate for him; it was also a major public-relations embarrassment for the event organisers.

The tragedy is diminished somewhat by the likelihood that, in the opinion of many historians, it never happened. Even so, it is no surprise that the next 2,400 years saw something of a lull in marathon running.

The race was only revived as part of the 1896 Olympics. And a key part in its rehabilitation was the epic poem Pheidippides, by Robert Browning.

Browning's verse describes the events that led to the inaugural run, which followed an invasion of Athens by the Persians. Pheidippides was "the best runner of Greece", according to the poem. And even before embarking on his most famous race, he was urgently dispatched to seek military aid from the Spartans - 140 miles away.

Despite the distance, we are told that Pheidippides ran to Sparta like a "fire" through a field of "stubble".

Unfortunately, the Spartans were not ready to join the coalition of the willing. So, soon, our hero was running back to Athens - another 140 miles - with the bad news, burning any stubble that had escaped the original conflagration. The question arises, therefore, whether it was the subsequent marathon that killed him, or the excessive mileage he was doing in training.

In any case, it is at this point in the story that, according to Blake, events take a dramatic turn. Pheidippides finds his way blocked by "a stoppage of stone". And there, in a moss-covered grotto, he sees "majestical Pan" - the goat-god.

Pan berates Athens for its lack of faith. But handing Pheidippides a sprig of fennel as a token of their meeting, he promises his support in the coming battle, saying: "Go bid Athens take heart, laugh Persia to scorn."

Of course, we in the modern world know that, when he had his "vision" of "Pan", Pheidippides was almost certainly suffering from acute glycogen deficit. The "stoppage of stone" sounds like the dreaded wall that long-distance runners know only too well.

At any rate, marathon runners who meet goat gods anywhere on the course the day after tomorrow are advised to top up their carbohydrate intake immediately, or else contact the nearest race marshal.

Yet, according to Browning, Pan made good his promise of support for the Athenians. The Persians were routed on the plains of Marathon (by what was, essentially, a Pan-nationalist front).

And it was only then that Pheidippides embarked on the inaugural "marathon" to bring the good tidings back to the city. In Browning's version, he was sent with the words: "Run, Pheidippides, one race more! The meed [sic] is thy due."

This is the first mention of liquid intake in the poem, although we know that Pheidippides had already covered at least 280 miles at high speed as well as fighting in a battle.

Furthermore, modern science tells us a fermented honey drink with high alcohol content is not the sort of thing that can be expected to keep top athletes going 33 per cent longer. But, in any case, the nearest drink station was at the end of the course - where, Browning says of Pheidippides, in terms that would make the most brass-necked PR consultant blush: "Joy in his blood bursting his heart, he died - the bliss."

As Browning very well knew, "joy" has never been recorded as a cause of death by any pathologist. It is much more probable Pheidippides succumbed from the combined effects of sunstroke - he was running in the middle of the day in Greece - and dehydration. This much is hinted in the poem's closing lines: "Gloriously as he began, so to end gloriously - once to shout, thereafter be mute: 'Athens is saved!' Pheidippides dies in the shout for his meed."

Nevertheless, modern runners must learn from his mistakes. The message for participants in next Monday's race is: (1) load up on carbohydrates beforehand; (2) hydrate properly during the race; and (3) don't talk to goats.

Also, be grateful that Pheidippides expired when and where he did, and not - for example - after the run from Sparta.

Otherwise, the Dublin City Marathon would be finishing in Cork.