THE CLINIC: Half-Marathon Muscle Cramping

Thu, 13 Sept. 2012 - 2:11 a.m. MT
Credit: ARA Staff - American Running Association

QUESTION:
When I reach mile 12 or so of a half-marathon or long run, my right calf cramps up, and has for years. What do you think of electrolyte replacement drinks, which promise an end to cramping. Information I’ve read in the past seems to indicate that the causes of cramping remain uncertain and therefore I’m skeptical of a surefire remedy. I’d like to cease experiencing these calf cramps but I shy away from electrolyte overloading. After all, I use Gu and PowerBars, yet the cramps remain. 
 
Leonard Wilson
Grand Rapids, MI
 
ANSWER:
Your problem is common, as is the belief that electrolyte loss is responsible. Theoretically, loading with an electrolyte replacement beverage might minimize the losses and shifts, but I am unaware of any controlled studies looking at this drink and rates of cramping. If your kidney function is normal (and one would think that it is if you’re running half-marathons) there should be no harm in giving the drink a try prior to long runs.
 
William M. Simpson, Jr., MD
Charleston, SC
 
ANSWER:
I’ve found that if a person’s calcium intake is too low, especially when their phosphorus intake is too high, they may be vulnerable to calf cramping.
 
Sarah Harding Laidlaw, MS, RD, MPA
Mesquite, NV
 
ANSWER:
The majority of research leads knowledgeable exercise scientists to conclude that exercise leg cramps are a result of deficient fluid, sodium and other trace minerals, and/or overheating of the body. Meeting fluid and mineral requirements would not be overloading. The Gatorade Sport Science Institute’s publication has a well deserved, highly regarded reputation, and I advise you to read further about electrolyte replacement and muscle cramping there: www.gssi.com.
 
Earl J. Carstensen, MD
Aurora, CO

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(RUNNING & FITNEWS® January / February 2009 • Volume 27, Number 1)



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