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Lock to Lock SwimRun with Simon Griffiths

Simon Griffiths is the founder and publisher of the Outdoor Swimmer magazine and a well-known member of the open-water swimming community. He’s also very accomplished swimmer so it was an honour to welcome him back for a second Swim Oxford event (he competed in the Lock-to-Lock 6K swim back in 2016, finishing with a very impressive time!). This year, Simon signed up for the Full Stump SwimRun.

Swim Oxford’s Lock-to-Lock Full Stump SwimRun is not an easy event. To get a sense of the challenge, Alan Scott’s article about it is definitely worth a read. Alan was 5th overall in the world series SwimRun and his solo winner’s time in our own event stood from 2019 until this year. He may be an impressive athlete, but his article graciously outlines his experience of the race. Alan’s course record was beaten in 2021 by Chris Goodfellow who set a blistering new course record in a truly outstanding and utterly amazing performance.

Simon and his race partner entered in the pairs category and braced themselves for the unfolding challenges of this unique event: long swims and lengthy, steep woodland climbs that leave even the best runners gasping for breath, tempted to walk, and longing for the cool river.

Having seen Simon in action on various sections of the course, his passion for swimming and competing in SwimRun events was very apparent to all in the Swim Oxford team. The pairs entry for SwimRun is all about supporting each other and bringing out the best in your race partner, making it a very particular sort of challenge. Their gutsy performance brought them over the finishing line in an admirable time. Here is his account of the September 2021 Lock-to-Lock SwimRun.

Simon Griffiths reflects on his performance at the 2021 Lock to Lock Swimrun

In rivers, the deeper and faster water tends to be on the outside of bends. If you’re racing downstream, this is usually the quickest place to be, even if you have to swim slightly further. At the start of the 2021 Swim Oxford Lock to Lock Swimrun, my race partner and I therefore made our way to the right of the river. When the start signal sounded, I put my head down and swam. After the usual flailing and floundering of a mass start, I breathed to my left and was surprised to see what looked like other competitors running on the water.

In the adrenalin-soaked confusion of the first few seconds of a race, this took a moment or two to process. I knew I was in a swimrun race, but running on water wasn’t something I expected to see. Had they discovered some new kit that allowed this? Was it in the rules?

Obviously, all that had happened was they had swum into the shallows on the inside of the bend and realised that running might be easier than swimming. I don’t know how far they got, or even if they gained any advantage as I stayed focused on my own swim, but it was certainly memorable. I wasn’t tempted to copy them. I knew there was plenty of running to come.

Compared to later swim sections, the river downstream of Eynsham Lock is relatively straight so navigation on the first swim was easy. The only thing to watch out for are trees and bushes along the banks that sometimes extend over the water, which we mostly managed to dodge. However, as swims often do in swimrun, it seemed to take much longer than it should have done. Wearing shoes while swimming not only slows you down, it also pushes you to work harder to compensate, even if you’re using a pull buoy to help counteract some of the drag. The bright yellow buoy marking transition was therefore a welcome sight. I emerged from the water gasping, but relieved.

Another feature of swimruns, given that water is low-lying, is that you often find yourself running uphill before you’ve had chance to steady your breathing after the swim. This was the case here too – and the hills were longer than I expected. I confess to forcing my race partner to slow down and walk in a couple of places. Still, the route was well marshalled and easy to follow, which was a good thing as I totally lost my sense of direction as the path wound through the woods. I grabbed some electrolyte drink at the feed station and made sure I ate a gel, even though I don’t like them. I knew I’d pay for it later if I didn’t keep up the energy intake.

After 6km of winding up and down and around in the woods, we emerged back onto the river path for a 1km flat section across the meadows. I was overheating by this stage, so welcomed the cool embrace of the river for the second swim, which was my favourite of the three. The river meanders here, so navigation is a little trickier. It’s not that you can get lost – it’s just sometimes hard to tell if the river is going to bend left or right from the limited view you get from the water. As I was leading my race partner on the swims, I needed to pay attention to keep the best line and avoid beaching us. It’s a pretty section of the Thames and I remembered to pay attention and appreciate being there.

Helpful volunteers hauled us of the water and pointed us in the right direction for the next run, a short dash of 320m. In my race plan, I’d made a note to eat something at this point, but I don’t think I did. There wasn’t time. I didn’t even remove my cap or goggles.

Faced with a choice of leaping from the lock wall back into the Thames or climbing down a ladder, I sheepishly chose the latter. If I do the event again, I will try to brave the jump – not because I think it would be faster but because I saw someone else do it and it looked fun.

Looking at my Garmin stats for the third and final swim, I saw our pace dropped by about 10s per 100m compared to the first swim. It’s normal to get tired and slow down, but a drop this big suggests maybe I got the pacing wrong in the first section. Alternatively, perhaps I should have paused for 30 seconds before starting to have another gel. There’s always something to learn and experiment with in swimrun.

On to the final run. This starts with a welcome flat section and we took advantage of it to eat something despite it only being 6km to the finish. I’m glad we did as once we hit the woods, the track turned uphill again. One thing I’ve learned about running this year is that I’m not as strong running uphill as a lot of other people – including my race partner – and this definitely needs to be a focus for training this winter. I dug deep and battled through but, yes, I did have to walk again. Fortunately, we were able to hold on to finish third team overall and second mixed team.

The after-race cake was spectacular and I fully indulged myself.

Top tips for this event
  • Consider calf guards and arm warmers for extra warmth on the long swim sections

  • Trail shoes are best for running through the woods but it’s manageable in trainers

  • Plan your nutrition, including the timing of when you eat

  • Train for hills

  • Bring a small box in case there is left over cake to take home

Simon Griffiths is the founder and publisher of Outdoor Swimmer magazine.

He also runs a website at


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