As a serious distance runner specializing in marathons, I always avoided anything terribly strenuous before the start of a race. I warmed up by walking or very light jogging, but I was always very careful to conserve my strength, knowing what was to come.

Then I trained for a 5K, and discovered that successful competitors in that event warm up much more strenuously than marathoners typically do.

It took me a while to break my old habits, but I discovered that hard sprints before a 5K could improve my time.