CLINIC: What's Causing These Cramps?

Wed, 22 Aug. 2012 - 8:19 p.m. MT
Credit: ARA Staff - American Running Association

I’ve run nine marathons and five half-marathons. Last March I experienced calf cramps that made it impossible to run, though I was able to walk. The cramps hit me at 20 miles. This February at another marathon the calf cramps hit me at 17 miles; I was able to walk the other nine miles. A month later the cramps started at the finish of the local
malf-marathon. Both marathons were very warm, in the 80- to 90-degree range. I was well-hydrated, however, especially in the second marathon. I am a 48-year-old female running 25 to 30 miles per week and have been in perimenopause for two to three years. Calf cramps never hit me until she recently. Any ideas? What do you think of performing blood tests for minerals or electrolytes? 
Lacy McGill
Franklin, LA
I feel there are several things that may be causing your cramps. Perhaps you are having electrolyte difficulties but I am not so sure that this is the real issue. Being perimenopausal could be contributing to this but I am not familiar with a specific link between the two.
More likely, the cause is muscle fatigue for one of two reasons, or even both. First, in slower runners there is a tendency to overload the calf muscles eccentrically (while your foot is planted and you are moving your body over your foot). This causes the fatigue, and cramp. Second, if you have any compression of nerve roots from your back you may be reducing the available power supply to your legs and causing the fatigue to happen sooner than it normally would. Compression would happen in people with a disc
protrusion (new or old), spinal arthritis, or both. Do you have any history of back problems? Even if if you don’t, sometimes this phenomenon can be silent as far as the back is concerned. Because running is a high-demand activity, the problem may be mild enough that it only shows up when there is high demand placed on the nerve. 
I suggest you see a sports medicine physician who is knowledgeable about the problem I outlined above. You might also check in with physicians in your area familiar with athletes who cramp due to excessive sweating and electrolyte loss.
John Cianca, MD
Houston, TX
Cramps can happen for a number of reasons, including dehydration, over-hydration, electrolyte abnormalities, and muscle fatigue. You didn't mention any problems on long training runs so we need to look at what is different on race day. If you are running at a faster pace than on training runs, fatigue is a problem. You should perform runs at your planned marathon pace during training; too often, pace is faster than this on short
runs and slower on long runs. Gradually increase runs at marathon pace from 8 miles to 15 miles.
Sweat rates are variable from person to person and will change with acclimatization and weather conditions. It is hot and humid in your region of the country, so weigh in without clothes prior to a long run and again following the run. Each pound lost is a 16-oz fluid deficit; you need to add the amount of fluid that you consumed during the run to this to estimate sweat rate. Repeating this in various weather conditions can provide a good range in sweat rate. A runner who is a little under- or over-hydrated should not experience problems. It is possible to consume too much fluid while running, causing
blood sodium levels to drop. This can cause swelling, cramping, nausea, vomiting, seizures, and worse. Salty snacks or supplements may help prevent this, but avoiding over-hydration is the key factor.
The fact that you can continue walking without a problem after cramping starts leads me to believe that fatigue may be the more significant factor. Incorporating strength training may also be helpful. To work on calf strength, raises should be performed at the edge of a step, dropping the heels down below the step and then rising onto your toes.
Cathy Fieseler, MD
Tyler, TX
(RUNNING & FITNEWS®May / June 2010 • Volume 28, Number 3)

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