Each month, I seem to develop a new pain related to running that keeps me from doing as well as I hope. Sometimes it's a busted toe, shin splint, sore quad, or weak ankles. This time, it's a pair of sore hip-flexors.
Why is this bad? My subjective experience is that a sore hip-flexor (I call it the area where your leg connects to the rest of your body) forces a short stride. No good. Time to stretch.
Pictured here are variations of a lunging stretch that is said to loosen up in that area. However, be careful not to overdo the stretch, as I'm sure this can cause injury.
I will be doing this myself over this week in preparation for my next race (which you will hear about early next week).
P.S. Might I add the rule about stretching: after cool-down only, not as a warm-up.