Gilbert Stuart--The Skater (Portrait of William Grant), 1782

"The unorthodox motif of skating -- indeed, any presentation of vigorous movement at all -- had absolutely no precedent in Britain's 'Grand Manner' tradition of life-size society portraiture. The painter recalled that when William Grant, from Congalton near Edinburgh, arrived to have his picture painted, the Scottish sitter remarked that, "on account of the excessive coldness of the weather . . . the day was better suited for skating than sitting for one's portrait." Thus artist and sitter went off to skate on the Serpentine River in Hyde Park. When he returned to West's studio with Grant, Stuart conceived the idea of portraying his subject on ice skates in a winter landscape, with the twin towers of Westminster Abbey far in the distance.

"In this innovative design, Grant glides effortlessly forward with arms crossed over his chest in typical eighteenth-century skating form. Except for his folded arms, the figure's stance derives from an ancient Roman statue, the Apollo Belvedere, a cast of which stood in the corner of West's studio."

https://www.nga.gov/Collection/art-object-page.39729.html