I ran the Treeathlon 5km race today in a new personal best of 21m 27s. That’s a full 75 seconds faster than my previous best. I put it down to the fast, flat course in Battersea Park (and figured had I not had the week I’d just had, I could have run even faster).

After the race, I looked at my Garmin GPS watch more closely to find that it had recorded the distance as 4.7km. I’ve also been trying out the new Nike+ iPhone GPS app and had set that off at the start, and it too recorded 4.7km. Two different devices, same distance recorded, makes it likely that they’re right, and the race distance was wrong. I ran home the long way and the devices agreed again, on a distance that I know having run it dozens of times.

Sadly, then, there’s no new PB. Had the course covered the full distance, I think I would have needed all of those extra 75 seconds, and probably a few more, to make it home.

The question, though, is why wasn’t it a 5km course? Did they measure it incorrectly? Did all of the runners in front of me take a wrong turn and miss out 300 metres of course? Was this an effort at a feel-good conspiracy? Will this be a new trend ahead of the Olympics designed to make all Brit runners feel like they’re getting faster?

Where is Dan when you need him. One explanation may be the corners. The question is do they measure the shortest route around corners or the average (middle of the road).I have no idea how many turns you would make but lets pretend that you ran around a 5 kom square course so over the lenght you would make 360 degrees worth of turns. An average road is 8 meters wide (2 lanes at 4 meters each). Given the inner edge is not a point but a curve you get some interesting distances.So the inner curve of the road (the inner edge of the road) is the shortest route and would be (assuming a 4m radius from a point) which in a complete turn is a circumference of about 50m. But, if you ran around the middle of the road, only 4m further out, the circumference is 200meters. So you would have to run 150m further to make the 360 degrees worth of turns.Its quite alarming how the distances increase if you run the edge or middle or outer edge of the course. So you were 300m down on the course. It does not seem to me that only a minor deviation in route through the corners is required over that distance to produce that result.As I said, where is Dan when you need him!

Where is Dan when you need him. One explanation may be the corners. The question is do they measure the shortest route around corners or the average (middle of the road).I have no idea how many turns you would make but lets pretend that you ran around a 5 kom square course so over the lenght you would make 360 degrees worth of turns. An average road is 8 meters wide (2 lanes at 4 meters each). Given the inner edge is not a point but a curve you get some interesting distances.So the inner curve of the road (the inner edge of the road) is the shortest route and would be (assuming a 4m radius from a point) which in a complete turn is a circumference of about 50m. But, if you ran around the middle of the road, only 4m further out, the circumference is 200meters. So you would have to run 150m further to make the 360 degrees worth of turns.Its quite alarming how the distances increase if you run the edge or middle or outer edge of the course. So you were 300m down on the course. It does not seem to me that only a minor deviation in route through the corners is required over that distance to produce that result.As I said, where is Dan when you need him!