Why is it called a "Charley Horse"?

[Peppy]

You know when you get kneed right across the old thigh. drops you like a sack of potatoes. why is that injury called a charley horse?

[Astroboy14]

According to this it comes from baseball… but I seem to remember a different explanation somewhere else…

[Astroboy14]

OK, Webster’s:

ballplayers’ slang, c. 1888; prob. with reference to a lame racehorse [Informal] a cramp or soreness in a muscle, specif. of the thigh, caused by strain

[stuyguy]

Pep, this question surfaces every six months or so. Ya’ gotta use the search function:

http://boards.straightdope.com/sdmb/showthread.php?threadid=5804

http://boards.straightdope.com/sdmb/showthread.php?threadid=11674

http://boards.straightdope.com/sdmb/showthread.php?threadid=49306

http://boards.straightdope.com/sdmb/showthread.php?threadid=68466

[Zarathustra]

From America’s finest news source:

Grimacing Congressman Quickly Drafts Legislation For Charley-Horse Research

WASHINGTON, DC-- Grimacing in considerable pain Monday, Rep. William Delahunt (D-MA) quickly drafted and introduced the 2001 Charley Horse Research Appropriations Act, which would allocate $100 million for “immediate research” to find a charley-horse cure. “Charley horses are a serious–oh, Jesus–medical condition that afflicts millions of Americans every day,” Delahunt told House colleagues. “And so let us–Christ, this kills–pass this bill as soon as possible.” When informed that the earliest the bill could be passed and signed into law is next Monday, Delahunt moaned and pounded the podium.