After much Googling, I am afraid I have come to the conclusion that I am most likely afflicted with what is known as "exercise-induced compartment syndrome," also known as chronic exertional compartment syndrome, which basically means that when I exercise, my calf muscles connected to my shin expand to such a degree that the sheath that contains the muscles, known as the fascia, does not have enough flexibility to expand and allow the muscle to function properly. According to the various websites I've seen, this leads to a very tight feeling in the legs, pain with each step, and tingling or numbness in the front of the lower legs and on the top of the feet as the expanding muscles and tight muscle sheath cut off blood flow to the peroneal nerve. Sound familiar?
The bad news about exercise-induced compartment syndrome is that the only foolproof method to completely relieve the symptoms is surgery. Apparently they cut along the length of the fascia, which gives the muscle room to expand without pain. However, surgery, like war, is a last resort. I have had this problem in the past, and I know from experience that when I drop a lot of weight, and generally get into better shape, my compartment syndrome symptoms virtually disappear. So I am hopeful that I can avoid a trip under the knife.
Currently, I have been able to reduce the symptoms by frequent deep tissue self-massage using The Stick. By massaging my tight calf muscles several times a day, I am able to effectively "pre-stretch" the muscles -- and possibly the fascia -- so that I do not get the symptoms while running. Most of the time, this is effective. Yesterday, I flung myself out the door and jogged 2 miles, walking twice for about 1-2 minutes each time, and I am very pleased to say that my legs were neither tight nor numb! However, a few days before that, I attempted a two-mile walk/jog, and my calves tightened up to the point where the pain was excruciating, and I had to walk most of the route. So, who knows. I have one week left until the race, and I will just do the best I can to keep my muscles limber until then.
I am also going to look into getting new shoes. I am told that several symptoms of compartment syndrome, and tight calves, and numbness, can be alleviated with the proper running shoes. Now, I had thought that my running shoes fit me just fine. But I haven't actually gotten fit for running shoes in seven years -- I have been using the same model ever since I was fit in a New Balance running store in 2001. All my friends who run in DC tell me to go to the Georgetown running company, where they will watch me run on a treadmill, and give me a shoe that will solve all of my problems. I am looking forward to this magical shoe, and I plan to go there as soon as the 5K is over. Well, maybe that week, as I am pretty sure that right after the 5K is over, I will be limping home and crawling into bed.