legs and lower back; lower body
Refers to the legs and the lower back/hip area as a functional unit, often in contexts of physical strength, mobility, or health.
As you get older, your legs and lower back become weaker.
I strengthen my legs and lower back with a daily walk.
Figurative extension: the base or support of an organization, system, or argument. Often used with 弱い or 強い.
This plan has a weak foundation.
Reforms are needed to strengthen the organization's underpinnings.
I run every day to strengthen my legs and lower back.
As you get older, your legs and lower back grow weak.
My grandfather has strong legs and lower back for his age.
This company has a weak financial foundation.