Feet pounding, lungs bursting – and with a bike race and a white-water kayak course still to go. It may not sound like fun, but for a growing army of amateur iron-men and women, extreme fitness challenges are now a big part of the Irish summer.
Adventure Racing, extreme-marathons, triathlons, open-water swimming and other intense fitness challenges are enjoying a boom time here, with new events being added to an already crowded calendar all the time.
And some, such as the 300km, 40-hour, running, biking, map-reading and kayaking Beast of Ballyhoura challenge, can make a mere 26-mile marathon look like a walk in the park.
If you prefer your extreme sports to be more of a sprint affair, then tomorrow's extreme fitness challenge in the West, which bills itself as "the biggest one-day Adventure Race in Europe" may be the one for you.
Gaelforce West, a 67km blast through Connemara and Mayo, which will bring over 2,200 competitors (and their friends) to the Westport-Castlebar region as they prepare to hike, kayak and run.
Gaelforce provides a multimillion-euro boost to the region and draws competitors from all over the world.
With events that cram in 10 marathons in 10 days and names like The Beast, The Raid, The War (Wicklow Adventure Race), The Warriors Run and The Hell and Back, it might seem like an extreme, macho world.
But the multi-sport and adventure racing craze is particularly popular with 30- and 40-somethings (even over-50s are not unusual) and the lycra-clad ranks often have as many women as men pounding up mountain passes or sprint-swimming across lakes.
The boom in extreme fitness challenges may be linked to our economic woes. Several recent studies suggest that in times of crisis, people see getting fit as a way to de-stress but also as a way of taking control of their lives and their environment in deeply uncertain times.
The fitness industry has been described as "recession proof". Studies show that participation in marathons, for instance, increases during an economic downturn.
Clean living and regular exercise also makes financial sense for people with less disposable income and has proven psychological benefits.
"I see more and more people getting into biking, running, hill-walking, as a way to de-stress," says Beast of Ballyhoura race director Ivan Park.
"It's not expensive once you get the basic equipment and it's a way of challenging yourself. There's an amazing sense of achievement. And it's addictive – that's definitely the right word for it. You start off running and then you want to take it further at every step."
Corkman Richard Nunan was part of a four-person team (three men, one woman) who completed the Beast of Ballyhoura, a frenetic race through Cork, Limerick and Tipperary, over the August Bank Holiday weekend.
For Richard and his team, the Beast was merely a warm-up for the main event. They fly out to Costa Rica in November to represent Ireland in the World Championships of Adventure Racing, a nine-day, 1,029km foot, bike and raft race over mountains, down rivers and through the rain-forest.
"We will have to get regular sleep in Costa Rica," says Richard.
Married with two young girls and living in Leixlip, Co Kilkdare, Richard (42) regularly runs or cycles (sometimes both) to his job with an IT company, often doing up to 55km on his daily commute.
"You have to fit it in around work and family life. It takes a lot of planning and when it comes to the events, you have to have your strategy and your prep all worked out.
"I've always been into sports. I competed internationally in kick-boxing but I was looking to get involved in a team sport, try something different. I was probably past the stage of joining a GAA team so I got into triathlons, but I found that they were too short for me.
"I love Adventure Racing because it's not just about being fast or super-fit. You have to navigate the course, carry all of your gear, think about your strategy on the move – it's a brilliant challenge and the social aspect of it is great, too."
Richard's four-person team (most adventure races require teams to have at least one female member) will usually train individually and plan their strategies and prep via email or Skype. The sport has a big strategic element, as competitors are required to plan their routes (with the aid of basic maps) on the move.
Equipment can be expensive. Richard's latest bike cost him over €4,500, but he says it can be done on a tighter budget. And with entry fees into most races around the €60 mark, a weekend camping and racing in Connemara comes in much cheaper than a city break.
"I say token female because that actually does take a bit of the pressure off you," she says.
"For everybody on the team, there will be some point over the 40 hours where you get a knock, run out of power or get hungry. And we all have to help each other get through it.
"It's not really about the winning. It's definitely about competing but the number one aim is to complete.
"Even just getting to the end is a big achievement."
Taryn took the traditional route to extreme Adventure Racing, starting out with biking, then triathlons and Ironman events and now she is going to be part of the Irish team competing in the World Championship race in Costa Rica.
"I can't even think about that at the moment now, because I've got a lot of training and other races to get through first. Plus, I have been out injured for over a year so I'm beginning to panic a bit," she says.
Taryn loves the competition and the camaraderie but she also enjoys the often remote regions they race through.
"I started off doing the biking and triathlons because I wanted to see more of Ireland, but then I realised that you can see so much more and go to places that you would never normally be with Adventure Racing.
"Some of the places we race through are just so remote and beautiful. And it's safe, you are with your teammates. You are really challenging yourself. It's an incredible experience."
Taryn had some company from home this year on the Beast – she persuaded a friend from her local bike club to volunteer to join a Swiss team that had lost their female member at the last minute.
"She's pretty fit, a great mountain-biker, but it was the first time she tried anything like this. She may not talk to me for a couple of months."
The Beast went well for Richard and Taryn and their two teammates. They came fifth out of 20 teams. Next stop is Costa Rica in November and six non-stop days competing in the world's toughest adventure race.