THE London Triathlon is an immense and exciting event, attracting about 13,000 competitors a year, including the likes of Jenson Button and Vernon Kaye.

East London’s Excel Centre is transformed into a giant transition area where competitors swap from the swim stage to the bike stage to the run stage and spectators can enjoy a huge exposition showcasing the latest triathlon gear as well as cheer their loved ones over the finish line.

The atmosphere inside the centre is buzzing and with different race waves starting at half-hour intervals throughout the day there is a permanent stream of people crossing the finish line and swimmers in wetsuits heading to the start.

I decided to enter the sprint distance category which involves a 750m swim in the dock next to Excel, a 20km bike ride on the roads around the centre and a 5km run done in laps along the waterfront.

My wave started at 2.30pm on Saturday, August 7, and I headed down there an hour early to rack my bike and soak up the atmosphere. Once I had figured out where I was coming into and going out of transition and munched a banana I put on my wetsuit and nervously headed to the swim assembly to collect my uniform green swim hat.

After a quick warm-up I plunged into the surprisingly cold water to line up with my fellow 400 women competitors at the start line.

After arranging myself near the back of the pack – I didn’t fancy being swum over in the mad dash to get ahead – I waited for the start horn.

Then we were off and although the first 100 metres were a bit hairy I managed to find a space in among all the women and settled into a rhythm for the swim.

Having practised in Hampstead ponds and the Serpentine, the dock water was a little petrol-tasting but I just focused on swimming around the buoys and getting to the exit platform.

I actually started to enjoy the swim, which was the part I had been most dreading, and it went well apart from when my goggles flew off due to another errant swimmer’s leg.

After just under 20 minutes I scrambled out of the water and it was quickly off with the wetsuit – which went into a plastic bag – and then a run back to my bike where I dumped the bag and put on my helmet, sunglasses and trainers.

The bike leg was a lot more enjoyable with great support from the spectators cheering you on and some great views of the City of London.

Done in two laps it took me just under 50 minutes and apart from the occasional bout of driving rain it was good fun and the encouragement from other competitors was a great spur.

The run leg was 5.4km and involved two laps around the waterfront of Excel. I enjoy running so this part of the race was the best and the route was lined with noisy spectators, including my family, cheering people on.

All in all the triathlon was a challenging but exhilarating experience – much more fun than plain running and great for toning up all parts of the body.

The training is varied meaning I never got bored of going to the gym and the day itself made all the training worth it. I will definitely be taking part next year – and maybe I’ll even tackle a longer distance!