Quoted from the Grammarist.
"The
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grind is usually inflected
ground in the past tense and as a
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.
Grinded might be considered incorrect in some contexts, but it has grown more common over the past several decades. It’s especially common in
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sports commentary and writing, where
grind means
to overcome adversity by playing hard. Based on
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, this sense of
grinded has been around at least since the 1960s."
The version from the 1900, has fallen out of use, the one used today is a new coining, and is fully in the realm of slang, using it is incorrect, and makes you sound ignorant, like a child, or a non-native speaker. You are getting your grammar from sports commentators, not the best source.