O.O'Brien

I’ve been doing a few street orienteering races around London recently. These are generally in the evening, when it’s dark, but I don’t need to geek out with a head torch as street lighting is normally sufficient to be able to read the map. The races are score races – you choose your own route and aim to get as many controls in 1 hour, with stiff penalties for being late back.

Here’s my route from tonight’s LOK event in London’s West End, as viewed in Ascent’s very cool map. The start was actually at the same place as the finish (chequered flag) but my GPS only gained reception after a few minutes of running. My route included an “interesting” stretch along Oxford Street, weaving in and out of the Christmas shoppers, then down Carnaby Street, across Regent Street, and into Theatreland, Soho, Chinatown and Covent Garden, before heading back to the University of London, where the finish was.

Another interesting thing – my HR during the race has a distinctive pattern – dipping noticeably every time I stopped at a control. A “control” on a street race like this one, consists of writing down a word you would only know if you were at the correct place, into a box on the back of the map. Examples included the name of the pub in front of you, how many pillars in the church entrance, and Statue of William who? (The Lamb & Flag, 6 and Pitt, in case you were wondering.) Unlike a normal race, where with good “flow” and forward planning you can almost keep running while punching, you generally have to stop for a good 10 seconds to write down the answer. Hence, the noticeable dip, 21 times, corresponding neatly to the 21 controls I visited, and the final dip at the finish. My highest HR, 190bpm, was during a long, straight run, around halfway through, between the two clusters of controls that I visited.

Here’s an extract, again from Ascent, for a SLOW street race in suburban Wimbledon, that I ran a few weeks ago. Only part of my race is shown. Here, the colours on the route correspond to the speed I was travelling at. Dark blue is slowest and green is fastest. The blue generally occurs at the points where I’m at a control – I typically make a sharp turn here too, due to my possibly non-optimal route to the next control. I had difficulty finding the plaque on a church in the top-middle of the picture, hence why I was walking (dark blue) around it. Caxton road was on a hill, hence why I’m going fast (green) one way down it. At this resolution, you can see where I crossed each road, and whether I went straight across, or at a diagonal, or even just ran down the middle of the road to avoid slow pedestrians.

Ascent is a very impressive program, and is working great so far with my Garmin 305 wrist-mounted GPS and HR monitor.

ps. Altitude estimation is hopeless with GPS – apparently I climbed 1170m in tonight’s one hour race. In fact, the race was completely flat, I probably actually climbed no more than 30m in the entire race. Momentary echos off the high buildings in central London will probably have caused this apparently impressive climbing feat.

Here’s an analysis, in Ascent, of my orienteering today, at the November Classic in the New Forest. See my Attackpoint training details for the race analysis. Click for the full-size version.

The blue line is my altitude. This is pretty inaccurate due to GPS calculations of altitude being inherently flawed. For example, I’m pretty sure I didn’t drop down that low int he first third of the race. However, it is useful as a relative guide.

The red line is my heart-rate – not smoothed. The colours behind it represent my heart-rate zones, so you can see I was in the anaerobic zone for much of the race, but was in the “red line” zone for quite a bit, including at the tops of a couple of the hill climbs, and at the sprint with the finish line in sight at the end. The three bubbles mark the three points where my HR was highest (187, 189 at the tops of the two hills, and 189 at the finish.) Overall I kept my HR pretty constant throughout this race. This was deliberate, I was slowing slightly for the latter half to keep it in my desired range.

The green line is my smoothed speed – averaged over 1 minute intervals during this 82 minute race. I was surprised to see my speed change so much during this race, but I guess this is typical orienteering, with many vegetation changes, on/off track running, and direction changes.

Times when I was standing still – there were a few unfortunately – have been removed.

You can see almost every control – as a dip in my smoothed speed. There’s 21 dips, corresponding to the 21 controls on the course.