This guy trained for a 250km running race across the Sahara in a submarine decompression chamber!

By Brad Williams | 4 Minute Read

We meet a lot of interesting people training for epic events in odd circumstances doing what we do, but if we had to rank them, Gary Ashton would likely get into the Top 5!


Gary is a commercial saturation diver who helps maintain the oil and gas infrastructure in the North Sea off the coast of the UK. We met Gary at the Marathon des Sables Expo in London late last year where we Sweat Tested him to help him nail his hydration strategy for 7 days of running through the Sahara.


When chatting to him during his test, we were fascinated to hear about the extreme conditions he works, lives and trains under for big chunks of the year and we thought you would be too, so Brad sat down with him to learn more...


So, Gary, can you tell us a bit about your work and the extreme conditions you're under?

Well, I generally work on the seabed at depths of 100/150m. For me to do this I have to be compressed in a decompression chamber for up to 28 days at a time. The chamber is actually on the boat and then the diving bell takes us from the chamber to the seabed.

I generally spend up to 6 months of the year (in 28 day stints) sealed in this chamber unable to get out until I've decompressed!

For understanding, if we were diving 100m it would take approx 5 days to decompress from this depth. It works the opposite way to altitude training, so you have an increased partial pressure of oxygen, which means you produce less red blood cells.

So, when you eventually reach the surface after 'deco', you feel pretty lethargic (very similar to jet lag) and very pale due to a lack of vitamin D. It'll take up to a week or more to rebuild your red blood-cell count and get back to normality.

Since training for the Marathon des Sables earlier this year, I feel like I've been able to cope with this much better, but you do still have good and bad days.

Sounds brutal! And so what does your training plan look like when you're on the job?

Whilst I'm in my diving chamber my training consists of yoga, callisthenics workouts and step ups with a 10 kg kettle bell in my backpack. I don't work out every day as it'll depend on the work I'm doing on the seabed.

I do yoga every morning before diving and I really think this has been an essential part of my training while under pressure. It helps me to get focused for the day in hand, it helps me to breathe and to really get the cardiovascular system working and it helps to loosen me up as, again, we don't get to move around much in the chamber. Last the yoga gives me my own personal space for 20/30mins, which is bliss!

I've been doing callisthenics/primal movement for a couple of years now and this has really helped to get me strong in my core. I've done different types of training for years, but callisthenics is amazing. It strengths all those little fibres in your body instead of just trying to pump up the main muscle groups biceps/triceps etc.

Again, with this type of workout you're using your breath to control the exercises instead of letting the exercise control you. Stay slow, calm and collected and it's amazing what you can achieve. Just breathe!

Last of all is step ups! I had to try and think of something to up my heart rate and get the legs working. It's not like I can run for miles, so this is the best I could come up with. I feel like a hamster on a wheel sometimes, but I just switch off and step away. I've did about 2-3 hours of stepping a day as the MdS got closer but mixing it with callisthenics.

Basically I was just trying to help maintain my fitness levels whilst in the chamber.

But what I've noticed massively as I've gotten older (I'm in my 40s) - and maybe this is my 'secret weapon' - is that recovery is the key. I've been able to maintain my fitness then come out of my chamber and do a 40 mile ultra a week later!

My callisthenics strength has been maintained and I've been able to do stuff I didn't know I could. My trainer Stephen Bell at Wildfoot is gobsmacked sometimes and we both believe the recovery is helping.

When I'm at home, the only thing I'm doing differently from the above is running, but generally the same routines apply.

Rather than doing step ups, could you simply walk back and forth on the submarine?

I haven't really got the space to walk as the chamber is only about 6-7 meters in length, so step ups it is! I'd get dizzy walking around in circles with such a short distance. I try to count steps but I always lose count after the first couple of rounds. (I am a man - I can't do two things at once!)

I use the clock on the wall and do different variations of timings but generally I just switch off or sing away to myself in Helium singing mode. There's not much funnier than singing to the Beatles when breathing a Helium/Oxygen mix!

Gotcha. And what's the longest duration/amount of steps you have covered in one session?

Oh, I'll do up to 3 hours somedays if I've got the day off due to bad weather or operational reasons, but generally I'll get a 1-2 hour session in with some good stretching or yoga moves.

What were your goals for the Marathon des Sables heading into the event then Gary?

Well, as my training regime isn't what you call 'normal', I was hoping to be in the middle of the pack. I went in with an open mind and was really looking at the event as a spiritual experience where I go and just enjoy my surroundings and be around like-minded, crazy folk!

Well, you ended up doing a little better than 'middle of the pack didn't you! (Gary placed 56th out of 752 finishers, covering the ~250km in an impressive 27:58:24). Not bad given the bulk of your training was done under water 🤣Congrats on an epic performance Gary and thanks for sharing your story!

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