Jogging is my activity of choice to stay fit. I was on my high school track team, and generally have tried to keep up with it in my adult life. I’m a fair weather runner – I’m not one of those dedicated souls who are out running in the freezing rain of a NJ February, but in the spring-summer-fall I try to keep active with it.
Like with everything else, it is good to have a focal point for training, and for me, I try and run a few 5k races each year. They help keep me honest with my training, and give me goals to try and reach.
Races fit in nicely to my project, because they record your time, and post your performance publicly on a web page (just like I am doing). I have not kept good records over the past decade of my running times, but I was able to do a little online digging to see what races I could find. Here is a chart of the finishing times of 5k races I was able to uncover:
There are a few interesting things to notice about this plot. First is the dead area for about 5 years between 2002-2007. Not coincidentally, this corresponds to my first five years as a dad. Not that I did not continue to run during this time, but I did it far less frequently, and often with a jogging stroller. I ran a few 5ks during this time, but a few were with other people or with the kids, and I wasnt running for speed, so I left those out.
You’ll see that my down time took its toll on my return to action in 2007. But the last few years I have been diligent in running a few races each year. I am amazed at how consistent my times have been in the last four years – 9 races, at different times of year and different conditions, all within 60 seconds of one another. I had no idea I was that predictable!
But I was really interested in the trend line, especially going back 10-12 years. The slope of this line indicates the time increase associated with my slowing down as I age. The slope is 0.17, meaning that on average every year my 5k time has increased by 0.17 minutes, or roughly 10.3 seconds of increase in time per year. (techie note: line was fit using robust regression – lmr() in R – due to the sparse data and outliers).
So, is this a ‘normal’ aging curve? It turns out we have data for this!
Compuscore is a company that does the timing for 5k runs, so they have lots of data on typical times for people of different ages. For every race, they report, in addition to your time, what they call a “PLP” – Performance Level Percentage, to allow comparisons between men and women of different ages. You can think of it as a percentile for your age/gender class. I have consistently run at about a 50% PLP. On this web site, you can look up what your PLP is for a given time, or calculate the time given a PLP. I came up with this table, which covers men in the age range of my plot above.
|Age||5k Time (50% PLP)||Seconds Increase from Prev year|
This table says that 30 year old men – who stay at the same level of fitness with respect to their peers – have an expected increase in their total 5k time of 3 seconds per year . By the time you get to 41 (where I am now), your time is expected to increase at 12 seconds per year! So my 10.3 seconds per year increase over this time period is somewhat in line with what we would expect given the above chart.
I thought I would zoom in on those last 4 years, the ones where I’ve been so consistent (see below). Despite the consistency, the trend line is still upward (that is, slower). BUT, my regression line slope has slowed to 8.6 seconds per year. So, at least temporarily, it seems I am keeping one small step ahead of father time.