I've done the necessary maths and the calculation wasn't difficult. In one sense at least.
Had I been wearing Nike Vaporfly shoes when I ran my first London Marathon I would very likely have achieved my target of finishing inside four hours.
No big deal, agreed, but it was of concern to me on that April day. And such concerns are shared every year by thousands, millions, of ordinary runners, never mind the escalating levels of club and elite performers. Some market.
Had I been wearing Nike ZoomX AlphaFLY shoes – in which Eliud Kipchoge proceeded to his startling sub-two hour "assisted" marathon in Vienna last October – I would have been even more likely to have achieved my goal.
And had I been running behind an arrowhead formation of constantly changing, world class pacemakers, on an almost perfectly flat and largely straight course, having trained assiduously at altitude for several months, with minutely calibrated drinks being handed to me as I followed the time-guide mark of a green laser light beamed down by a pacing vehicle….whoah, whoah, back up…calm down.
On that now rather distant day in London the only unusual performance-enhancing element of which I was aware was the timely appearance of one of my daughters on The Highway, round about the mark at which one was supposed to hit The Wall.
A mixture of shame and pride supercharged a hunched shuffle at that point into more orderly progress.
The calculation involved that is not so easy relates to the decision over whether it is ethically right to buy the apparently guaranteed super-charging effect of these new generation of shoes with a combined carbon-plate and compressed foam, which experts maintain can improve performances in marathon running by between four and five per cent.
"Relatively new" generation that is – the Vaporfly range has been around for four years. The new generation, whose arrowhead as far as Nike is concerned is the AlphaFLY, apparently improves performances by eight per cent…
World Athletics has been under pressure for some time to offer a ruling on whether this performance-enhancing footwear is legal, or a technological step too far.
And, on Friday (January 31), they produced a complex answer to a complex question.
There is one overarching ruling – for now. If shoes have been on offer "on the open retail market" – either online or in store – for a minimum of four months, they can be freely used in competition.
So that's yes to Vaporfly shoes. It's okay. You can trim ten minutes or so off your marathon time if you are prepared to lay out around £250 ($330/€300) for shoes that, according to extensive research, do what they say they do, but at the cost of durability.
Although in so doing, you may always have a mental asterisk appended to your time…
As for the AlphaFLY shoe – no go. World Athletics revealed an "indefinite moratorium" would be placed on any shoe which does not meet a series of requirements, including on the size of the sole and only having one "rigid embedded plate or blade (of any material) that runs either the full length or only part of the length of the shoe".
An expert review group appointed to review competition shoes concluded "new technology in the soles of road and spiked shoes may provide a performance advantage and there is sufficient evidence to raise concerns that the integrity of the sport might be threatened by recent developments in shoe technology".
"If a shoe is not openly available to all then it will be deemed a prototype and use of it in competition will not be permitted," World Athletics said in a statement.
A new working group, comprising bio-mechanics specialists and other qualified experts, will be established to conduct further research into new technology which is being incorporated into competition shoes and trainers.
Bryce Dyer, a sports technologist and specialist in product design at Bournemouth University, told Reuters that the new range of carbon plate shoes were "the equivalent of bringing a gun to a knife fight".
Others have gone on record as saying that wearing the shoes is like putting springs on your feet.
Athletics' world governing body has been here before.
In 1957, a year after failing to make the Russian team for the Melbourne Olympics, Yuri Stepanov set a surprise world record in the high jump of seven feet, one inch, or 2.16 metres.
And when, shortly afterwards, Russia's Olympian Igor Kashkarov, who had cleared only six feet, 10½ inches to finish third in Melbourne, managed a jump of seven feet, ¼ inch, questions began to be asked.
The French sport paper L’Equipe published a picture of Stepanov in action, with the soles of his shoes appearing unusually thick and bouncy.
Paul Mericamp, the spokesman for the International Amateur Athletic Federation, said: "The rules say nothing about the foot gear of a high jumper, but the federation has to take a stand on this phenomenon."
Before long the rules did say something about suitable footwear for high jumpers and the spring-heeled soles were banned. But Stepanov's world mark stood. Just as Kipchoge's unofficial world mark of 1 hour 59min 40.2sec will stand, and it is now even more remote.
The stats on the effectiveness of the new carbon-plate shoes developed by Nike – which are now being replicated by a range of commercial rivals – are compelling.
Of the 36 podium positions in the six World Marathon Majors last year, 31 were claimed by athletes wearing Vaporfly shoes.
There was a close parallel ten years ago with the position the International Swimming Federation (FINA) found itself in regarding the full-length high-tech swimsuits that had been developed by Speedo, which compressed the body and trapped air to aid buoyancy.
Multiple Olympic champion Michael Phelps was the campaign poster boy for a product launched just a few months before the Beijing 2008 Olympics, where 94 per cent of all races were won by swimmers wearing the suit.
When 17 world records fell to those in Speedo garb at the European Short Course Championships in December 2008, with many competitors increasing the effect of the suits by wearing two of them, FINA felt obliged to step in and the body-length bodysuits were banned from January 2010.
Asked about the direction of travel on this question ahead of the World Athletics Athlete of the Year Awards in Monaco in October, World Athletics President Sebastian Coe said that the issue was still being examined, but he made it clear that he was uncomfortable with the general idea of trying to halt technological advances.
The position established appears sensible, particularly as the option for further actions in the light of detailed research has been reserved.
After four years of sales for the Vaporfly shoes and their ilk it is hard to imagine how World Athletics could have policed a ban.