Meaning of 生命線を守る in the following sentence

Question

Context: a boxing champion is arm-wrestling against another boxer. The champion is on the verge of losing, but he still doesn't give up, so the other boxer thinks:

このチャンピオン君

ちぎれそうでちぎれへん

生命線ってヤツを守る〝底力〟はなかなかやね…

In Kenkyusha dictionary I found these two examples:

生命線を守る guard one's lifeline

生命線を脅かす threaten [menace] sb's lifeline

So it seems that it is a common collocation, but what is the meaning in the sentence above and in general? Other than referring to the lifeline on the palm of one's hand or to something of vital importance, can 生命線 simply be a synonym of "life"? Can it refer to a person's survival istinct?

In the manga page, there's actually a line that is "tied" to his fist. While here you can see how he "breaks" the line of the opponent when he beats him.

I would also be grateful if you could explain the value of that で after ちぎれそう. Thank you for your help!

Answer 1

This type of 生命線 (usually figuratively) refers to something that keeps you alive when you are in danger. Loss of 生命線 means death (biologically or figuratively). It can be a physical rope, food, oxygen, money, internet connection, or anything depending on the type of danger you're facing. 命綱 is also used in a similar manner.

In this manga, 生命線を守る底力 refers to increased strength exerted only when you're close to defeat. (So...something like this. In Japanese there is a word 火事場の馬鹿力; is there a generic term for this in English?) That visible line is an illustration of this concept.

で after ちぎれそう is simply the te-form of だ.

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Bonus:

• 生命線 also refers to this line on the palm.
• ライフライン in katakana usually refers to basic infrastructure of a society (electricity, gas, water, etc.) See: ライフライン
• Lifeline in English also refers to emergency telephone counseling. This is sometimes referred to as ホットライン in Japanese.