A few years ago I was running the New Hampshire Ten Miler. It is a rolling course and on every downhill I caught the same woman, who then passed me on the next uphill. At some point we figured that we would run better if we ran together, so every time I passed her I would wave to her to follow, and when she passed me she would call out "come on!" I had a good race that day and it re-enforced the idea that when we run together we help each other by smoothing over the rough parts of our race. Sometimes focusing on someone else helps me transition through difficult phases of a race.

But do the numbers bear this out? Or is it just that it makes me feel better to go on auto-pilot for awhile and let someone else set the pace?

So what I want to know is, if you have a running buddy in a race, does it smooth out your pace?

So if you want to run a steady, evenly paced race, don't run with your running buddy. Runners tend to speed up and slow down with their friends. Instead, get out there and look for the competition and run on their heels. But if they slow down, dump them right away and latch onto someone else.

If your running purely for fun, run with your buddy. But if your competing, run with the competition.

Once again I am turning to the Vermont City Marathon (2017) for my data. It had nearly 2,000 runners, and the results included splits measured at the 10k, 10 mile, half marathon, 20 mile and finish. So for every runner I can calculate their pace for the five different segments of the race.

(Actually 1,983 finisher)

Data from coolRunning

The pace for different groups of runners through the five segments of the Vermont City Marathon. Each group is 100 runners, by order of finish.

Variation of a runner's pace as a function of the pace group. The size of the crosses indicate the statistical uncertainty.

Time between a runner and one other runner who ran a similar race. A pair of runners who run every segment within seconds of each other are very likely "running buddies".

Variation of a runner's pace as a function of how close do they keep to the competition. The closer you run to other people, the steadier your pace. The people who run very close to other (circled data point) are the most steady runners.