Noun, Suru verb, Intransitive verb
standing on tiptoe and stretching one's back to make oneself taller; stretching oneself
彼は背伸びをして失敗した。He bit off more than he could chew. overreaching oneself; overstretching oneself; trying to do something beyond one's ability; pushing to the limit
Also written 背延び【せのび】