Learn Hardcore Japanese: muri wo suru to karada no guai ga waruku naru. - If you overdo it, your physical condition gets worse.

Here, と marks a conditional meaning “if/when,” especially for a natural, automatic result. It’s used for general truths or predictable outcomes: 無理をすると “if/when you push yourself too hard,” then the result happens: 体の具合が悪くなる “your condition gets worse.” With this と-conditional, you typically can’t put a request/command/volitional in the result clause. Compare: 春になると暖かくなる “When spring comes, it gets warm.”

Do I need the を after 無理? Can I say 無理すると?

With noun + する expressions, を is common but often optional in casual speech. So both 無理をする and 無理する mean “to overdo it/push yourself too hard.” Using を can feel a bit more careful or neutral; without を feels a touch more casual. Your sentence works fine as 無理すると体の具合が悪くなる in everyday speech.

Why is it 体の具合 and not 体が? Can I say 体が悪くなる?

In Japanese, the thing that is “bad” here is the condition (具合) of the body, not the body itself. So we say 体の具合が悪い/悪くなる. Saying 体が悪くなる is unnatural because “bad” isn’t typically predicated directly of the body; we describe the body’s condition/state instead.

Why does the sentence use が after 具合 and not は?

Adjectival predicates often take が for what’s being described: Xが悪い. So 体の具合が悪くなる is the default. You could use は to make a contrastive topic (e.g., “As for the body’s condition, it gets worse”), but without a contrast in context, が is natural and idiomatic.

Why is it 悪くなる and not 悪いになる or 悪くてなる?

With i-adjectives, the pattern for “become Adj” is: Adj(−い) + く + なる. So:

悪い → 悪くなる “become worse”
高い → 高くなる “become higher/expensive” For na-adjectives and nouns, use に: 便利 → 便利に/静か → 静かに + なる. Note also the transitive counterpart: 悪くする “make (something) worse.”

What’s the nuance difference among 体の具合, 体調, 調子, and 気分?

体の具合: the condition of the body; fairly neutral/physical; also used for things (“機械の具合が悪い”).
体調: overall health/physical condition; common in health contexts. 体調が悪い/体調を崩す.
調子: condition/performance/“form” (machines, people’s performance). 体の調子が悪い is fine.
気分: how you feel subjectively (mood, nausea, dizziness). 気分が悪い = “I feel sick/queasy,” not necessarily poor health overall.

Can I replace と with たら, なら, or すれば? What changes?

たら: 無理をしたら体の具合が悪くなる is fine; a bit more “if it happens (on an occasion), then…” and less law-like than と.
すれば: 無理をすれば体の具合が悪くなる also works; a straightforward conditional.
なら: 無理をするなら体の具合が悪くなる can work as a warning/advice if the context is “if you’re going to do that / if that’s the case,” but it’s less generic-rule-like than と.

What timeframe does 悪くなる in non-past express here?

Non-past in Japanese covers general truths, habits, and the future. Here it’s a general rule and also implies a future consequence: “If you overdo it, your condition gets worse/will get worse.”

Is there a more polite version of the sentence?

Yes: 無理をすると体の具合が悪くなります。 To give gentle advice, you could say 無理はしないでください (“Please don’t overdo it”) or more casual 無理しないでね.

Is 具合 only for people? I’ve heard it used for machines, too.

Right—具合 means “condition/working order” in general. For people: 具合が悪い = “feel unwell.” For things: この時計の具合が悪い = “This watch isn’t working well.” Adding 体の clarifies you’re talking about the body.

How do you pronounce the words here?

無理: むり (muri)
体: からだ (karada)
具合: ぐあい (guai). Some older speakers may say ぐわい, but standard is ぐあい.
悪くなる: わるくなる (waruku naru)

Why are there spaces between the words? Do Japanese normally write that way?

No. Standard Japanese writing does not use spaces between words. Textbooks and teaching materials sometimes insert spaces to help learners parse the sentence. Normally you’d see: 無理をすると体の具合が悪くなる。

Who is the subject here? It just says “becomes worse.”

Japanese often omits the subject when it’s understood. Here it’s generic “you/one/we,” or the speaker, from context. You could explicitly say 私は or あなたは, but it’s usually unnecessary: the sentence itself reads as a general warning.

Is there a stronger or more idiomatic way to say “your health will suffer” in this context?

Common alternatives:

無理をすると体調を崩す (“you’ll wreck your condition/health”)
無理をすると体を壊す (stronger: “you’ll harm your health”)
無理をしすぎると体の調子が悪くなる (“if you overdo it too much, your condition gets bad”)

Could I just say “無理をすると体に悪い”?

Yes: 無理をすると体に悪い means “Overdoing it is bad for your body.” It’s shorter and more general. 体の具合が悪くなる focuses on the condition actually becoming worse; 体に悪い states it’s harmful in principle.