With a huge increase in the number of people pulling on their trainers and a plethora of races to choose from, running challenges are having to become increasingly insane to capture the imagination.

Eastern Daily Press: David Oliver was first to complete the inaugural Norfolk 100km race in a time of 10 hours, five minutes and 38 seconds.David Oliver was first to complete the inaugural Norfolk 100km race in a time of 10 hours, five minutes and 38 seconds. (Image: Archant)

And now a new event in Norfolk is pushing entrants to the edge.

The Norfolk 100km, which is run along the Peddars Way and Norfolk Coast Path, returns for a second year next month.

The race, which is reputed to be slightly longer than the two and a bit marathons advertised, starts at the Bailey Gate in Castle Acre on Saturday, June 11, at 7am, and entrants have until 11pm to reach the finish line at the Runton Road car park in Cromer.

Last year 21 of the 24 runners who started the inaugural race finished within the 16-hour time limit, with the first, David Oliver, home in a time of 10 hours, five minutes and 38 seconds.

Eastern Daily Press: Runners will follow the Norfolk Coast Path through Blakeney.Runners will follow the Norfolk Coast Path through Blakeney. (Image: Archant)

And, with 49 already registered this year and entries still open, the number of runners completing the course is expected to double.

Organiser Kevin Marshall, 56, from Bury St Edmunds, who runs fitness firm Positive Steps Fitness and Wellbeing, said: 'Basically, it's come around because for the last 20 years the Norfolk coast and all its long distance trails have been my playground.

'What we try to do is provide inspirational courses and try and provide interesting places to run and what can you have better than Norfolk? The national trails here are just magnificent.

'All our events are for everybody, they are not elite races, so there are generous (cut off) times, and it's about getting out and enjoying the trails and pushing your own boundaries in an inspirational atmosphere.'

Eastern Daily Press: Competitors have to negotiate a shingle beach around the 50 mile mark.Competitors have to negotiate a shingle beach around the 50 mile mark. (Image: Archant)

Among the trickier sections of the ultra marathon, which passes Holme next-the-Sea and includes water stations every 20km, is a five mile section of shingle between Cley and Weybourne.

But organisers insist the spectacular scenery acts as a welcome pain relief and puts the region on the map.

Kevin said: 'Last year everybody loved it and several of them have signed up to do it again.

'Every part of it is unique. The Peddar's Way is very different from the Norfolk Coast Path, the bits around Brancaster are very different from the bits around Sheringham, and I think that's what makes it so interesting. Every stage of the journey is just new and fascinating and keeps you motivated, you're not worrying about the pain you might be going through.

Eastern Daily Press: The view from the Norfolk Coast Path in Blakeney.The view from the Norfolk Coast Path in Blakeney. (Image: Archant)

'Runners can expect to go through every possible human emotion that is out there, from elation once they've crossed that finishing line to: 'Why the heck am I here?' And everything else in between. That's what makes it so great. And the camaraderie on these events, it's not like some of the road races where people are just out for the time, people look after each other.'

Unlike road racing, it is rare for an ultra runner to be asked their finishing time - just completing the course is often challenge enough. So why do it?

'I think it's about discovering your own boundaries and what you're capable of – mentally and physically,' Kevin explained. 'Physically, once you can run a marathon, it's mentally that stops you from doing any more. So, once you can overcome that mental barrier, the world is your oyster.'

The race forms part of Positive Steps Grand Slam, which includes the Kings Forest 50km and Peddars Way Ultra.

And, after a low-key launch last year, organisers revealed they were keen to limit the field to 150 runners to protect the route.

Kevin, who will start the race and see every runner home, said: 'People are coming from all over for the race so Norfolk benefits, people are staying in the area so it's benefiting the local economy. So we're not just taking from Norfolk, we're giving something back.'

To enter the Norfolk 100km, log on to the following website: www.positivestepspt.co.uk/events/norfolk-100km/