September: Pain

   All runners cast their pain into fables of good and evil. The story goes something like this: good pain steals upon you in the final throes of a sprint, when lungs ache and oxygen-starved leg muscles feel an anaerobic burn-or else it throbs in your hams and calves the day after you extended your customary long run by four miles. However achieved, good pain makes you stronger. Evil pain, on the contrary, is injury, a sabotage that throws workouts, goals, self-worth-even identity into sudden doubt.

   Runners need these silly myths to help distinguish trouble from gain. The truth, however inconvenient, is that all pain results from stress to bones and tissue, and the remedy for both woes is rest. The chief difference between training and injury is the recovery time you allow for your aches to subside, for your body to mend.

   This notion horrifies running coaches who know better than to trifle with injury. Scarred hamstrings and bum knees can destroy a running career. Months of accomplishment can be derailed with a single overoptimistic workout. To be sure, pain that persists for more than an hour after a run augurs trouble. Swelling that lingers for more than a day calls for a doctor. Chronic pain of any kind tells you there's something wrong with the way you run. Don't be glib about injury; you'll pay the devil for months on end.

   So what about good pain, that reaffirming soreness that arrives the day after a hard run? It's the 12- to 24-hour delay that tells you it's friendly. Lactic-acid buildup in the muscles was the old explanation, proof that your workout had tipped into anaerobic territory. This theory is quickly losing its scientific street cred. You'd feel the effects of lactic acid during and immediately after your workout, and the pain would diminish, not increase, overnight. This-is one reason that stretching does little to relieve aches produced by a hard run, despite widespread belief to the contrary.

   More likely, microscopic tears in the muscle beckon white blood cells to repair the damage. As these cells accumulate, they release a number of chemicals that create local muscle pain, which peaks 12 to 24 hours after the affliction. Tom muscle sounds suspiciously like injury, and this is where myths about good pain and bad pain fall apart. To equate training with injury defies our better instincts. Yet they're actually the same thing.

   The moral to this fable is that most runners tend to be cavalier about hard workouts. When muscles heal, they're stronger than before, capable of withstanding greater stress. This is the training effect. But healing is where this magic happens. And the old remedies for injury - RICE (rest, ice, compression, and elevation) - apply to training as well. When you find yourself limping after a grueling workout, abandon efforts to classify the ache as injury or merely fatigue. Pack it in ice. And take the next day off.