The long run: how to prepare for a marathon

'I'm going to be controversial here, Dublin City University's sports scientist Niall Moyna warns. "Is it good for people who can't run a marathon in under 3½ hours to be doing it in the first place?"

“The best can cover 42km in under 2½ hours, but five hours is a lot of running for someone without proper conditioning. There is now evidence that it may negatively impact on their heart function,” he says. “Then you must think about the joints and tendons, particularly as the average person running a marathon may be slightly overweight.”

Moyna, a sports lover and exercise physiologist at the university, has run marathons. He says people should set themselves realistic challenges, such as five five-kilometre races in a year, or a half marathon, rather than doing a full marathon and then hanging up their shoes. “It’s an awful pity when the guy ran from Marathon to Athens it wasn’t five kilometres. It would have served society better,” he says.

Those who want to cover the full 42km in one race, however, will find there are plenty of insights from sports scientists. Most important is to have trained for 15-20 weeks beforehand and to be well fuelled on the day of the race. Everyone has two fuel tanks in their body, Moyna says: their fat reserves and their carbohydrate reserves.

An average person holds about 100,000 calories of fat and 3,000 calories of carbohydrate. The higher the intensity at which you run, the greater your reliance on carbohydrate. If you are untrained, you will burn through this tank quickly. If you run out of carbs, then you hit the wall, because your body can’t get energy quickly enough when you use only fat.

That can be avoided by proper carb intake. With training, athletes can also teach their muscles to use more fat, thus reducing reliance on carbs and allowing them to run for longer at higher speeds.

Carbodhydrate intake
James Morton, exercise researcher at Liverpool John Moores University, has tested muscle biopsies from runners who take carbs before and during exercise – in line with standard advice – and those who fast before and during training. "When you feed carbohydrates all the time, you block the adaptation of making more mitochondria [the cells' energy factories] in the muscles," he has found.

General advice on carbohydrate intake for endurance has shifted, says Ruth Kilcawley, an elite performance nutritionist with Athletics Ireland. The emphasis on loading up on carbs days before an event has fallen off, but do fuel up on the day.

“Take additional carbohydrates in the form of gels or fluids early in the race. Certainly by the 10km mark you should be replacing the fuel you’ve used,” she says. “I like rice-style cake and banana bread.”

But don’t overdo the water on the day. The most important thing is to be hydrated the day before. Drink when you are thirsty.

Kilcawley also stresses correct protein intake: too often, amateur runners focus on chicken, when they need oily fish two or three time a week to support good immune health, and red meat such as beef and lamb, which helps with iron levels.

Top athletes might eat twice as many carbohydrates as amateurs, yet protein intake is similar. Research shows timing matters though. “When protein is taken throughout the day, it has been shown to have a very significant effect on muscle protein synthesis and the prevention of muscle breakdown,” says Kilcawley. She advises eating some protein five times a day.

There is a limit to the amount of glucose absorbed in an endurance situation, so mixing it with fructose is a good idea. “A good breakfast is porridge with honey or fruit and combined with a fruit juice and toast with jam – different types of carbohydrates – and it’s important to have it two to three hours before the event, because as it gets closer to start time, your digestive system gets affected as nerves and adrenaline kicks in,” says Kilcawley. If that’s difficult, have a good carbohydrate-heavy supper the night before.

If you wish to stay up with the race leaders, though, you probably should have chosen your parents, says Moyna. Genes matter. “There is no single magic bullet that determines if you are going to be a power athlete or endurance athlete,” he says. “Many genes are involved, and they are influenced by diet, training and lifestyle.”

Known genes account for “5 per cent of the variability of performance” .

Final advice: “If you make a plan, stick to it as, when the exhaustion and dehydration set in, you can’t think straight,” says Kilcawley.

Ed Coughlan, sports scientist at University of Limerick, says to keep a steady pace and be conservative early on.

Fuel up: Avoiding athletic energy deficit
Nutritionist Ruth Kilcawley warns that many Irish women are not adequately fuelling themselves for running. They leave themselves open to impaired immunity, ill health, increased risk of bone fracture and reproductive problems.

“People assume that if they weren’t eating enough food, then they wouldn’t be able to train, but that’s not the case,” Kilcawley says. “It can be hard to spot.” She’s talking about “athletic energy deficit,” which happens when runners don’t take enough energy on board. The body keeps the basics going – movement – but sacrifices secondary physiological functions, in particular the immune and reproductive systems. Some female runners struggle with menstrual cycle problems.

Kilcawley recommends that athletes eat a regular, nutritious meal after a training session. If that’s not possible, a chocolate milk drink has been proven to work.

Prof Niall Moyna at Dublin City University says that it is important to see the upsides of exercise too. “As a society we totally underestimate the value of exercise as a medical therapy. It is probably the cheapest form of medicine we have and it’s underutilised.”

DCU recently completed a study of men and women in their 60s, who had been referred by a cardiologist after having a heart attack, stent or bypass surgery. “We put them on a high-intensity training programme and they got tremendous benefits in fitness,” says Moyna. “In Ireland we have this culture that when people reach 65 they go out to pasture. Changing that culture is extremely important. People in their 90s benefit from increased muscle strength.”