I think this is a great chart of heart rate data against time. It compares my heart rate during an "out and back" time trial event, but 2 years apart. The red data is from earlier this year. Black is on the same course but 2 years ago in 2009. This year I was faster by almost 2 minutes and set a personal best for this course. The data tells me at least three things:
1. I could have tried much harder this year. Especially during the second quarter and last quarter of the race.
2. On an out and back course, wind will usually reduce the overall time. (There's plenty of stuff online that explains why). This year there was more wind than in 2009, and it was a tailwind on the way out and head wind on the way back. This is clearly evident in the data, the dip in HR being the turn point. Indeed, in 2009, it seems I was actually quicker on the return leg, but slower overall.
3. Considering the above observations, it's great that I'm faster this year! This must be combination of training and equipment - but I like to think more to do with training than equipment :)
4. Older does not mean slower!
The data is very informative and makes me feel that I can improve further. It was gathered using Garmin FR60 heart rate monitor, which I think samples heart rate every 5s. Yes, I know this blog is about working on bikes, but working out on bikes has got to be included in that!