Performance Advantage Coaching by Dr Will O'Connor

Pacing in endurance sport is one of the most essential aspects of performance. Regardless of your ability, if you start the race beyond your level of fitness you will slow down at the end. The severity of how much you slow down (blow up) will depend on the race duration and how far beyond your ability you went at the start. Heat and Glycogen: Two Factors Slowing You Down In some cases, the amount you slow down may be so drastic you are forced to stop. Blowing up can occur for two reasons. Heat:. You can only handle small variations in core temperature (97 °F (36.1 °C) to 99 °F (37.2 °C)). If you accumulate heat at a rate faster than your body can cool itself, you'll be forced to slow down to avoid heat illness. Sugar: As humans, we can only store a few 100 grams of glycogen (sugar) in our muscles and liver. We use glycogen aerobically and anaerobically as a high octane fuel for situations where fat can’t be used to produce energy fast enough. Starting too fast can us...

I had an amazing run at the Trail Trilogy 100km ultramarathon. Overall, I am incredibly happy with my effort and I am glad I implemented my 19-1 run-walk strategy, which I believe saved me on multiple occasions. HOWEVER, I felt like everything went to plan except for two sections. Looking back through my data, those two sections do stick out at me and I’d like to show them to you. Here is the raw output from TrainingPeaks, the software I use to analyse training files. To the untrained eye, it may look like a bit of a mess, but with a little background information, you can unlock a world of information. I’ll show you. Everyone slows down in an ultra First, if you clear out some of the excess data and only show heart rate and running power, you can see that I slowed down over the duration of the race. The rate at which I slowed down fits nicely into the results published in a 2004 study titled “Changes in Running Speeds in a 100 km Ultramarathon Race” (read here). The res...