This is the 5207th most frequent Russian word.
ногах
"Ногах" means "legs" or "feet" in the prepositional or dative plural form.
Here, 'на ногах' implies being in a standing position and able to move around, highlighting endurance or activity.
Она стояла на ногах целый день.
She stood on her feet all day.
In this sentence, 'в ногах' refers to the legs as parts of the body, emphasizing their physical state.
Силы в ногах совсем не осталось после бега.
There was no strength left in the legs after the run.
Here, 'на больных ногах' indicates the condition of the feet or legs, focusing on discomfort or ailment.