Learn Hardcore Polish: Lekarz proponuje, abyśmy po treningu spacerowali wolniej, żeby odpocząć. - The doctor suggests that after training we walk more slowly to rest.

aby means “so that/in order that,” and when you add the personal ending -śmy (first-person plural), you get abyśmy, which introduces a subjunctive (jussive) clause after verbs like proponować. The form spacerowali is actually the third-person plural past stem of spacerować, but in these subjunctive clauses Polish reuses the past-tense-looking stem (often without the particle by) to express “should walk.” So although it looks like past tense, abyśmy spacerowali means “that we walk/should walk.”

Why are both aby and żeby used here? Aren’t they the same?

Both aby and żeby mean “so that/in order to,” but with slight stylistic differences. aby is a bit more formal or literary, and it’s followed by a finite verb form (here introduced by abyśmy + spacerowali). żeby is more colloquial and pairs naturally with an infinitive when expressing purpose (e.g. żeby odpocząć = “in order to rest”). You could swap them (“żebyśmy spacerowali” or “aby odpocząć”), but this choice keeps the sentence clear and idiomatic.

Why is wolniej used instead of wolno or wolny?

wolny is an adjective (“free” or “slow” when describing something), and wolno is the adverb “slowly.” wolniej is the comparative adverb of wolno, meaning “more slowly” or simply “slower.” Here the doctor wants you to walk slower than usual, so wolniej is the correct comparative form.

What case is treningu in po treningu, and why?

After the preposition po meaning “after” (in a temporal sense), Polish uses the locative case. That’s why trening becomes treningu (singular locative). po treningu thus means “after the training” or “after the workout.”

Why is odpoCząć in the infinitive after żeby? Could we say żebyśmy odpoczywali instead?

Using żeby + infinitive (here żeby odpocząć) is a very common, concise way to express purpose (“in order to rest”). Grammatically you could form a subjunctive with a finite verb (żebyśmy odpoczywali = “so that we would rest”), but that sounds more like you want to continue resting or describes a wish, rather than a clear purpose. The infinitive makes the intended “to rest” purpose straightforward.

Are the commas before abyśmy and żeby mandatory?

Yes. In Polish, subordinate clauses introduced by conjunctions like aby and żeby are normally set off with commas. Here the comma before abyśmy separates the main clause from the first subordinate clause, and the comma before żeby separates the two subordinate clauses. Omitting them would make the sentence harder to parse.

Why is proponuje in the present tense? Could it be proponował?

Using the present tense proponuje (“proposes”) indicates that the doctor is making the suggestion right now or as a general recommendation. If you shift it to past tense (proponował), you’d imply the doctor suggested this at some specific past time. Both are grammatically correct, but the present tense is more natural for stating a current recommendation.