Learn Hardcore German: Meine Trainerin sagt, Muskelkater zeige, dass die Ausdauer wächst, solange der Schmerz nicht zu stark ist. - My trainer says sore muscles show that stamina is growing, as long as the pain is not too strong.

Direct speech would be:
Meine Trainerin sagt: „Muskelkater zeigt, dass die Ausdauer wächst, solange der Schmerz nicht zu stark ist.“
Here you’d see a colon and quotation marks, and the verb zeigt would be in the normal indicative form.
In the given sentence:
Meine Trainerin sagt, Muskelkater zeige, dass die Ausdauer wächst, solange der Schmerz nicht zu stark ist.
you have:
- a comma instead of a colon,
- zeige (subjunctive) instead of zeigt,
- and no quotation marks.

Those are all typical signs of indirect speech in German: you are reporting what she says, not quoting her exact words.

Why is it Muskelkater zeige and not Muskelkater zeigt?

Zeige is the subjunctive I (Konjunktiv I) form of zeigen for 3rd person singular.

zeigt = indicative (normal factual statement)
- Muskelkater zeigt, dass die Ausdauer wächst.
  → “Muscle soreness shows that endurance is growing.” (speaker states this as a fact)
zeige = subjunctive I, used in reported speech
- Meine Trainerin sagt, Muskelkater zeige, dass …
  → “My trainer says muscle soreness shows that …” (speaker distances themself; this is what she says)

Using zeige signals that this is what the trainer claims, not necessarily what the narrator asserts as an independent fact. This is standard in more formal or written German. In everyday spoken German, many people do use zeigt instead, even in indirect speech.

Could I also say „Meine Trainerin sagt, dass Muskelkater zeige, dass die Ausdauer wächst …“? How would that differ?

Yes, that’s also correct and actually the most typical version of indirect speech:

Meine Trainerin sagt, dass Muskelkater zeige, dass die Ausdauer wächst, solange der Schmerz nicht zu stark ist.

Differences:

You add the conjunction dass to clearly introduce the content clause.
Because it’s now a subordinate clause, the verb zeige must go to the end of that clause:
- …, dass Muskelkater zeige, dass die Ausdauer wächst …

So you have two “layers” of subordination:

Main clause: Meine Trainerin sagt, …
Subordinate content clause: dass Muskelkater zeige, dass die Ausdauer wächst, …
Subordinate clause inside that: dass die Ausdauer wächst …

The original version without dass and with verb in second position (Muskelkater zeige, …) is a stylistic variant: indirect speech without dass but still using the subjunctive. It’s somewhat more written/literary in tone.

Why is there no dass before Muskelkater zeige in the original sentence?

German allows two main patterns for indirect speech after verbs like sagen, meinen, denken:

With dass and the verb at the end:
- Meine Trainerin sagt, dass Muskelkater zeige, dass die Ausdauer wächst …
Without dass and verb in second position (like a main clause), but with subjunctive:
- Meine Trainerin sagt, Muskelkater zeige, dass die Ausdauer wächst …

The second pattern leaves out the conjunction dass and keeps a “main-clause-like” word order (subject first, verb second), but still marks indirect speech grammatically via zeige (Konjunktiv I).

This style is very common in newspapers and more formal writing. Learners are usually safer starting with the version with dass, which is straightforward and always correct.

Why is there no article before Muskelkater? Shouldn’t it be der Muskelkater?

You can say der Muskelkater, but article-less Muskelkater is also natural here.

The bare noun Muskelkater is used in a generic sense, similar to English:

English: “Muscle soreness shows that endurance is improving.”
(no the before “muscle soreness” – it’s a general phenomenon)

German works similarly with certain abstract, uncountable, or “mass” nouns:

Muskelkater zeigt, dass …
Schmerz ist normal. (Pain is normal.)
Sport ist gesund. (Exercise is healthy.)

So Muskelkater here means “muscle soreness in general,” not one specific instance.

You could also say:

Der Muskelkater zeigt, dass …

That usually feels a bit more specific, like “the soreness (you’re feeling now) shows that …” Both versions are grammatically fine; the bare noun is just more neutral/general.

Why do we have die Ausdauer with an article, but Muskelkater often appears without one?

Both nouns can appear with or without an article, but the nuance differs:

die Ausdauer here is understood as “your/the person’s endurance” in this context. The definite article die can refer to:
- a specific endurance that is relevant here (the athlete’s),
- or the concept of endurance as the attribute we are talking about.
Muskelkater without article is more like “muscle soreness in general” as a phenomenon.

You could say Ausdauer wächst without an article, but die Ausdauer wächst (or deine Ausdauer wächst) sounds more idiomatic because Ausdauer is conceived more as a quality of a person, while Muskelkater is often treated like a mass phenomenon you “have” (like Hunger, Durst, Schmerzen), which easily drops the article in generic statements.

Why is it die Ausdauer and not der Ausdauer or den Ausdauer?

The noun Ausdauer is feminine in German:

singular: die Ausdauer
it has no commonly used plural

In the clause dass die Ausdauer wächst, die Ausdauer is the subject, so it must be in the nominative case:

Nominative feminine singular: die Ausdauer

der Ausdauer would be dative or genitive, and den Ausdauer would be wrong (it would look like masculine accusative, but Ausdauer is feminine, so that form doesn’t exist).

Why is the verb at the end in dass die Ausdauer wächst and solange der Schmerz nicht zu stark ist?

Because dass and solange both introduce subordinate clauses. In German subordinate clauses, the finite verb goes to the end of the clause:

dass die Ausdauer wächst
- Subordinator: dass
- Subject: die Ausdauer
- Verb (finite): wächst at the end
solange der Schmerz nicht zu stark ist
- Subordinator: solange
- Subject: der Schmerz
- Adverb: nicht zu stark
- Verb (finite): ist at the end

So the rule is:

In a clause introduced by dass, weil, wenn, solange, obwohl, etc., the conjugated verb goes to the final position.

What exactly does solange mean here, and how is it different from wenn or während?

solange means “as long as” in a temporal and often conditional sense: it sets a condition that must hold over a period of time.

…, solange der Schmerz nicht zu stark ist.
→ “…, as long as the pain isn’t too strong.”

Comparison:

wenn = “if” / “when”
- …, wenn der Schmerz nicht zu stark ist.
  → grammatically fine, but wenn just sets a condition; it doesn’t emphasize the duration as strongly as solange.
während = “while” / “whereas”
- …, während der Schmerz nicht zu stark ist.
  → sounds odd here; während is typically “while (at the same time)” or “whereas (by contrast),” not “as long as (within acceptable limits)”.

So solange is best here because it combines time and condition: within the time span during which the pain remains not too strong, the statement applies.

What is the nuance of nicht zu stark? How is zu stark different from sehr stark?

zu stark = “too strong” (excessive, beyond a healthy or acceptable limit)
sehr stark = “very strong” (high intensity, but not necessarily a problem)

In the sentence:

…, solange der Schmerz nicht zu stark ist.
→ “… as long as the pain is not too strong.”

This implies there is a limit beyond which the pain is problematic or dangerous. Some pain is OK (maybe even normal), but if it becomes zu stark, that’s too much.

If you said:

…, solange der Schmerz nicht sehr stark ist.
→ “… as long as the pain is not very strong.”

that sounds more like “as long as it’s not very intense,” but it doesn’t as clearly express the idea of crossing a healthy boundary. zu stark fits the context of health/exercise better.

What case is der Schmerz in solange der Schmerz nicht zu stark ist, and why is it der and not den?

The noun Schmerz is masculine:

Nominative: der Schmerz
Accusative: den Schmerz
Dative: dem Schmerz
Genitive: des Schmerzes

In solange der Schmerz nicht zu stark ist, der Schmerz is the subject of the verb ist, so it must be in the nominative:

der Schmerz (nominative masculine singular)

den Schmerz would be accusative, which you’d use if it were the object of a verb:

Ich spüre den Schmerz. (I feel the pain.) → here den Schmerz is the direct object.

Why is it Meine Trainerin sagt (present tense) and not Meine Trainerin hat gesagt (perfect tense)?

Both are grammatical, but they have slightly different focuses:

Meine Trainerin sagt, … (present)
- Suggests this is something she says regularly or still says now.
- It can introduce a general rule or advice that remains valid.
Meine Trainerin hat gesagt, … (perfect)
- Refers more to one specific moment in the past when she said it.
- Feels more like “She told me (once) that …”

Since the content is a kind of general training principle (“Muscle soreness shows that endurance is improving, as long as the pain isn’t too strong”), present tense fits well: it sounds like a standing piece of advice she gives.

What is the difference between Trainer and Trainerin, and why do we say meine Trainerin?

German usually has separate forms for many professions and roles, depending on gender:

der Trainer = male trainer
die Trainerin = female trainer

In the sentence:

Meine Trainerin sagt, …

we have:

Trainerin (with -in) → clearly refers to a female trainer.
meine instead of mein, because Trainerin is feminine and mein/meine must agree in gender and case:
- Nominative masculine: mein Trainer
- Nominative feminine: meine Trainerin

So meine Trainerin = “my (female) trainer.”