strong legs
Refers to legs that are physically powerful or sturdy, often used in contexts like sports, hiking, or describing someone's sturdy lower body.
彼は力足で、山道も平気だ。
He has strong legs and is unfazed by mountain trails.
I do squats to build strong legs.
Compound of 力 (ちから, 'strength') and 足 (あし, 'leg'). The reading ちからあし follows standard rendaku-less compounding.