with all one's might; wholeheartedly; giving it everything
Idiomatic expression derived from the image of tying a twisted headband tightly, symbolizing determination and full effort. Used adverbially.
See also: ねじりはちまき
I studied with all my might to pass the exam.
彼はねじり鉢巻きで仕事に取り組んでいる。
He is tackling his work wholeheartedly.
全力で simply means 'with full power/effort' and is more straightforward; ねじり鉢巻きで adds a nuance of spirited, almost stubborn resolve.
Standard kanji-kana mixed spelling for this idiomatic expression.
Rarely used kanji form; the first kanji 捩 is uncommon.
From the practice of tying a twisted headband (ねじり鉢巻き) tightly around one's head to show determination and focus, often before a strenuous task. The adverbial form ねじり鉢巻きで literally means 'with a twisted headband on', figuratively 'with full resolve'.