Learn Hardcore German: Nach dem langen Tag spüre ich in meinen Beinen die Müdigkeit, aber innerlich bin ich zufrieden. - After the long day I feel the tiredness in my legs, but inside I am content.

Tag is masculine: der Tag (nom. sing.).
Dative singular masculine is dem Tag.
With a definite article in dative singular, the adjective takes -en: dem langen Tag.

So:

Nach dem langen Tag = correct (dative singular, masculine)
Nach den langen Tag = wrong (den would be accusative sing. masc. or dative plural, neither fits)
Nach der lange Tag = wrong (wrong article and wrong adjective ending)

Why does “langen” end with -en in “dem langen Tag”?

The adjective lang gets the ending -en because:

It comes after a definite article (dem).
The noun (Tag) is dative singular.

With definite articles, all dative singular forms (masc./neut./fem.) use -en on the adjective:

dem langen Tag (dat. masc. sg.)
dem langen Kind (dat. neut. sg.)
der langen Frau (dat. fem. sg.)

So dem langen Tag is exactly what you expect: nach + dative → dem, and then adjective ending -en.

Why does the verb come after “Nach dem langen Tag”, as in “Nach dem langen Tag spüre ich …” instead of “Nach dem langen Tag ich spüre …”?

German main clauses follow the verb-second (V2) rule:

The conjugated verb must be in second position (in terms of elements, not individual words).

Here, the whole phrase “Nach dem langen Tag” counts as one element in first position, so the verb comes second:

Nach dem langen Tag → element 1
spüre → verb in position 2
ich … → rest of the clause

So:

✅ Nach dem langen Tag spüre ich …
❌ Nach dem langen Tag ich spüre … (verb not in second position)

Why is it “in meinen Beinen” and not “in meine Beine”?

The preposition in can take either dative or accusative:

Accusative = movement into something (direction)
Dative = being in something (location, state)

Here, “in meinen Beinen” describes where the tiredness is felt (a state/location), not movement, so we use dative:

Nominative plural: meine Beine
Dative plural: meinen Beinen

Hence: in meinen Beinen (dative plural).

Could you also say “in den Beinen” instead of “in meinen Beinen”?

Yes, “in den Beinen” is grammatically correct and idiomatic. The difference is subtle:

in meinen Beinen – explicitly refers to my legs.
in den Beinen – more general / idiomatic, like “in the legs”, often used even when context makes it obvious we mean my legs.

Both are fine; the version with meinen sounds a bit more personal and concrete.

Why is it “die Müdigkeit” with a definite article, instead of just “Müdigkeit”?

In German, abstract nouns like Müdigkeit (tiredness), Freude (joy), Angst (fear) very often take the definite article when you’re talking about a specific instance or a clearly identifiable feeling:

Ich spüre die Müdigkeit. = I feel the (specific) tiredness (that has come after this day).
Ich spüre Müdigkeit. = possible, but sounds a bit more like “I feel (some) tiredness” in a more neutral, less concrete way.

In this sentence, “die Müdigkeit” is also the direct object of spüre, so it is in accusative singular (same form as nominative for feminine nouns):

Nom./acc. fem. sing.: die Müdigkeit

What is the word order rule for “spüre ich in meinen Beinen die Müdigkeit”? Could I say “spüre ich die Müdigkeit in meinen Beinen” instead?

Both orders are grammatically correct:

spüre ich in meinen Beinen die Müdigkeit
spüre ich die Müdigkeit in meinen Beinen

German allows some flexibility in the middle field (between verb and clause-final elements). Word order here mainly affects emphasis:

Version 1 (in meinen Beinen earlier) slightly highlights where you feel it.
Version 2 (die Müdigkeit earlier) slightly highlights what you feel.

Both sound natural. The original emphasizes the location of the sensation a little more.

What’s the difference between “spüren” and “fühlen” here? Could I say “Ich fühle in meinen Beinen die Müdigkeit”?

You can say “Ich fühle in meinen Beinen die Müdigkeit”, and it’s understandable, but:

spüren often emphasizes perceiving a physical or subtle sensation:
- Ich spüre die Kälte. – I feel (sense) the cold.
- Ich spüre in meinen Beinen die Müdigkeit.
fühlen is a bit broader and is used a lot with emotions and states:
- Ich fühle mich müde. – I feel tired.
- Ich fühle mich glücklich.

In this context, spüren is slightly more idiomatic for sensing tiredness in your legs as a physical sensation.

What does “innerlich” mean here, and what kind of word is it?

innerlich here functions as an adverb, meaning something like “inside / inwardly / internally”.

As an adverb, it doesn’t change its form (no case, no gender, no plural).
It tells us how or in what way the speaker is satisfied: internally, on the inside, even though physically they are tired.

So “innerlich bin ich zufrieden” ≈ “on the inside I am content.”

Why is it “aber innerlich bin ich zufrieden” instead of “aber ich bin innerlich zufrieden”? Are both correct?

Both are grammatically correct:

aber innerlich bin ich zufrieden
aber ich bin innerlich zufrieden

The difference is one of emphasis:

In 1, innerlich is placed in the first position of the second clause and is therefore emphasized:
- “…but internally I am satisfied (even if outwardly I am tired).”
In 2, ich is in first position; the emphasis is more neutral or slightly on the subject “I”.

German allows you to front different elements for emphasis, as long as you keep the V2 rule (here: bin is in second position in both sentences).

Why is there a comma before “aber” in “… die Müdigkeit, aber innerlich bin ich zufrieden”?

The comma is required because aber is a coordinating conjunction linking two main clauses:

(Ich) spüre in meinen Beinen die Müdigkeit – main clause
innerlich bin ich zufrieden – main clause

In German, when aber connects independent clauses, you must put a comma before it:

…, aber …

So the comma marks the boundary between the two clauses.

Why are “spüre” and “bin” in the present tense, even though the day is already over (“nach dem langen Tag”)?

German often uses the present tense to describe:

current states and ongoing feelings
situations that are true “now”

The phrase “Nach dem langen Tag …” gives the time frame (“after the long day”), but the feeling of tiredness and satisfaction exists now, in the present.

So:

Nach dem langen Tag spüre ich … = Now, after that long day, I feel …
It doesn’t require the past tense, because you’re not narrating past events, you’re describing your current condition.

Could you also say “Nach einem langen Tag” instead of “Nach dem langen Tag”? What’s the difference?

Yes:

Nach einem langen Tag – After a long day (more general, “any long day”)
Nach dem langen Tag – After the long day (a specific long day both speaker and listener know about, e.g., the day that just happened)

Grammatically:

einem langen Tag – dative singular masculine with indefinite article
dem langen Tag – dative singular masculine with definite article

The original sentence suggests a particular day (e.g., today), not just any generic long day.

Why is “Beinen” in the plural here? Could I say “in meinem Bein”?

You could say “in meinem Bein” (singular), but normally both legs feel tired after a long day, so native speakers naturally use the plural:

in meinen Beinen – in my legs (both)

Using the plural just matches the real-world situation more closely and sounds more natural here.