Marathons shmarathons. These days the only way to flaunt your fitness is at a Tough Mudder race, a gruelling 10 - 12 mile obstacle course designed by the S.A.S which hammers every single muscle in your body.

InStyle's senior features writer Lucy Pavia had a fit of madness and signed up to this Saturday's race. In preparation she quizzed Nigel Thomas, Tough Mudder's chief training officer on what to expect.

So Nigel, why is Tough Mudder so punishing on the body?

'It's a tried and tested system of training within the Special Forces. Jumping, crawling, running, walking, pulling, pushing utilising muscles in the body that do not normally get used.'

Which muscles can we expect to absolutely cane the next day?

'Climbing the walls activates muscles that cannot really be replicated in the gym (unless you have a wall) from your calves to your triceps and most of the muscles in between have some involvement in getting you over that wall. The funky monkey utilities your core muscles and upper body strength, obviously your leg muscles are used to get you through the water after you fall off the bars!' 

What kit should we bring? Are gloves a good idea for the log vaulting thing?

'Gloves are great to have but not essential. They protect the hands when crawling through the dirt and mud but can be a hindrance when climbing ropes or doing the monkey bars. Do not wear new trainers as they'll get ruined. Cotton t-shirts in cold weather are a no-no and for the men please no pink leotards...'

What is the hardest obstacle on the course?

'For many of the ladies the Funky Monkey [monkey bars] and the walls are hard because of the upper body strength required to get over them.'
What should we do to prep the day before?

'Drink plenty of water, eat sensibly and make sure you have all your kit ready, including your shower and dry kit for after the event. Have someone with you to take photographs and especially at the end, after the Electroshock!' 

If I need to cram in some last minute training what do you recommend?

'Last minute training does not work, it needs to be a concentrated training period. This will very much depend on what you are currently doing. Circuits, such as the ones on the Tough Mudder website, work best. They are tried and tested by us and adapted from the Special Forces training syllabus. They are not meant to be easy, but the benefits are huge. What's great is that you do not need a gym to train.'

What misconceptions do people have about Tough Mudder? How do these normally change after doing it?

'I can't do it, it's scary, I don't like cold water, I'm not strong enough, fit enough, I can't run. I recently trained a group of ladies and I heard all these excuses. They all finished and wow the confidence they now have to take on different life challenges, not only taking on more Tough Mudder events in the future, is fantastic. The mind can be a such a powerful tool if it's working for us or it can be such a negative tool working against us.'

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By Lucy Pavia / @lucypavia