背筋を伸ばす

せすじをのばす

to straighten up one's back (e.g. stand up straight, sit up straight); to hold one's head high

Meaning

expv5s
to straighten up one's back (e.g. stand up straight, sit up straight); to hold one's head high

Example sentences

背中合わせに立って腕を組んで、一方が前屈する事でもう一方の背筋を伸ばす体操を、子供の頃よくやりましたよね。

That exercise - backs together, link arms, one bends forwards while the other stretches their back - we did that a lot as children, didn't we?