It's hard work keeping up with Dr Niall Moyna. He walks fast. He talks fast.

He is totally immersed in his subject.

When it comes to exercise physiology, he is willing to talk genetic polymorphisms, hypertrophic stimuli, muscle biopsies, energy expenditure, even large grants from the US National Institute of Health. But ask him about himself, and the torrent of talk abates to a hesitant flow.

This is just as well, as we have completed a whistle-stop tour of the state-of-the-art facilities in the exercise physiology labs in DCU and a rest is definitely indicated. So, where did education begin of this prodigious researcher, who became director of the applied physiology lab in the University of Pittsburgh, and an adjunct professor to Trinity College, Hartfort, Connecticut, and who has recently joined DCU as a senior researcher?

Niall Moyna started out at St Macartan's College, Monaghan. "For the first three years in school I never opened a book. I was very good at sport," he summarises. He left St Macartan's for the Marist College, in Dundalk. "I woke up at 15. I wanted to do PE but I needed Irish and I didn't know it. So, after my Leaving, I went back to St Macartan's to do Irish. You had to pass an oral test in Irish because Macartan's was a teacher-training college.

"I'm not sure where I graduated from. When I got a place it was the National College of Physical Education, then it became Thomond College, now it's part of UL."

He returned to Monaghan to teach in St Macartan's and to coach the Monaghan senior football team. His life appears to be punctuated by the fortunes of the team: "We lost the centenary cup final to Meath. That was the start of the Meath renaissance. That year, I went to Purdue University in Indiana. I wanted to study exercise physiology, with Dr David Lamb." He takes down a hefty well-thumbed physiology of exercise textbook, with Dr Lamb's name on the cover.

Purdue had 47,000 students with classes starting at 7.30 a.m. and finishing at 10 p.m. "A big change from 200 students in Limerick. It took time to adjust but it was a wonderful experience." He returned to Monaghan, again to teach at his old school and to coach the football team. During that time, Monaghan won the Ulster Championship.

"After Cork beat us in the all Ireland semi-final I left to do a PhD in the University of Pittsburgh - that was in 1988, to anybody whose clock is not adjusted to Monaghan football time." There was no GAA in Pittsburgh so Moyna turned his attention to the track, setting up a track team of post-collegiate runners. Three of them made the US Olympic team. "I'm a lucky guy. I guess I can pick the right people." It was during his time in Pittsburgh that Moyna realised the therapeutic role that exercise could play in a number of chronic diseases, particularly heart disease, with its high prevalence in Ireland.

"I'm very interested in how our genes affect how we respond to different interventions, such as diet, exercise and drugs. There are small variations - one or two amino acid sequence changes, polymorphisms - and these contribute to human variation in both health and disease." He suggests that, in 10 years' time, we will walk into our GP clutching a CD-ROM containing our genetic blueprint. The prescription we walk out with will be based on this blueprint.

Individualised medicine, based on genetics, will take a lot of the guess-work out of the treatment of patients, he predicts. "Imagine you walk into a doctor's office with high cholesterol. He knows from your genetic blueprint that exercise will decrease your cholesterol by 90 per cent and diet by 10 per cent.

"Somebody else might have genetics that mean that exercise will have little or no effect, and they must concentrate on dietary and pharmaceutical interventions." He hastens to add that exercise will, of course, have other beneficial effects for this patient.

In fact, his mantra is that we should all exercise daily, for 20 minutes (or more, if we choose). "Most people jump on an exercise programme that they can't sustain. Just walking for 20 minutes a day, every day of the year, is enough for cardiovascular health," he says. And, yes, he does take his own advice and runs for 20 minutes everyday, on grass, and at weekends he goes for a longer run, in Clontarf or the Phoenix Park, usually for 60 minutes.

Moving indoors, he recently published a study comparing the energy expenditure on various exercise machines. Unsurprisingly, this attracted a lot of media attention: he fielded more than 50 phone calls. Energy expenditure was greatest on the treadmill and ski simulator in men and women, with a rowing machine also figuring well for women.

While much of Moyna's work is concerned with disease, the performance lab in DCU is used to measure the performance of elite athletes. "Our aim, eventually, is to become aligned with the National Sports Council and become one of their satellite sites to provide sport science support for international and Olympic athletes."

A lab is currently being fitted out so that Moyna can participate in a study with 10 US universities that aims to understand the genetic variation leading to difference in muscle development and plasticity between normal individuals. The DCU study will look at 50 people a year, for four years, and while most of the work will be done at DCU, Dr Stephen Eustace of Cappagh Hospital will carry out MRI scans.

The results should have important implication regarding muscle function in common disease states, such as aging, muscular dystrophy and atrophy during space travel. (Moyna says people will live in space and the response of muscle to zero gravity is a real issue.)

The NIH grant, of $5.6 million, is the largest given to date to look at normal human tissue. The study was conceived in the US, and it is only because Moyna returned to Ireland that there is any European involvement.

So, why did he come back? "Hartford Hospital was probably the best job I will ever have. I was so immersed in my work there. I was directly responsible for 38 studies at one stage. If I had got any more deeply involved, I couldn't have left."

Ireland was booming, he says with a grin, acknowledging the current post-boom state of affairs, and he got in contact with DCU, which has a reputation for being a progressive institution.

The dean, Malcolm Smith, "impressed the socks" off Moyna, "talking like an American". When DCU then advertised a position, Moyna applied and was successful.

Yes, it has been a difficult transition, he admits. After eight years of pure clinical research, he now has to take classes. There are 90 undergraduates on the BSc in sports science and health., and 12 graduate students. He also had to start anew, setting up a research programme.

"It's a challenge I welcome, although I still miss the US," he says.