Akademik

скор на ногу
• ЛЕГОК (ЛЕГКИЙ) НА НОГУ; СКОР <СКОРЫЙ> НА НОГУ all coll
[AdjP; subj-compl with copula, subj: human (all variants) or modif (variants with long-form Adj); fixed WO (variants with short-form Adj)]
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⇒ one walks (or, occas., runs) with a spirited step, quickly, and can keep going for a long time without tiring:
- X легок на ногу{{}}≈ X is light on his feet;
- X is light-footed (nimble-footed).
     ♦ Ксюте бегать в школу приходилось далековато, но она была легка на ногу... (Евтушенко 2). Ksiuta had to run five versts to school every day but she was light on her feet... (2a).

Большой русско-английский фразеологический словарь. — М.: ACT-ПРЕСС КНИГА. . 2004.