Efter træningen har jeg ondt i musklerne, men ømheden forsvinder som regel dagen efter.

Because Danish uses verb-second word order in main clauses.

When something other than the subject comes first — here, Efter træningen — the finite verb must come next:

• Efter træningen har jeg ondt i musklerne.
• Literally: After the workout have I pain in the muscles.

So the pattern is:

• Normal order: Jeg har ondt i musklerne.
• With a time expression first: Efter træningen har jeg ondt i musklerne.

This is very common in Danish and often surprises English speakers.

At have ondt i noget means to have pain in something or for something to hurt.

In this sentence:

• jeg har ondt i musklerne = my muscles hurt / I have pain in my muscles

This is a fixed expression in Danish. Very common examples are:

• Jeg har ondt i hovedet = I have a headache / My head hurts
• Hun har ondt i ryggen = Her back hurts
• Har du ondt i benet? = Does your leg hurt?

So it is best learned as a chunk:

• have ondt i + body part

With have ondt i, Danish normally uses i for pain felt in a body part or area of the body.

So you say:

• ondt i musklerne
• ondt i ryggen
• ondt i knæet

This is just the standard Danish pattern. Even if English might phrase things differently, in Danish i is the natural choice here.

Because Danish often uses the definite form where English might use the, or sometimes where English uses no article at all.

Here is each one:

• træningen = the training / the workout
• musklerne = the muscles
• ømheden = the soreness

Why definite?

• Efter træningen: this refers to a specific workout, usually the one just completed or understood from context.
• i musklerne: when talking about your body parts in a general but specific-to-you sense, Danish often uses the definite form.
• ømheden: this refers to the specific soreness already implied by the first clause.

Danish definite forms are often attached to the noun:

• en muskel → musklen
• muskler → musklerne
• en træning → træningen
• en ømhed → ømheden

They are related, but not the same.

• ondt refers to pain or it hurts
• ømhed refers to soreness or tenderness

So in this sentence:

• har jeg ondt i musklerne = my muscles hurt
• ømheden forsvinder = the soreness disappears

A related adjective is:

• øm = sore, tender

Examples:

• Jeg er øm i benene. = My legs are sore.
• Ømheden er værst om morgenen. = The soreness is worst in the morning.

So ømhed is the noun formed from øm.

Using ømheden repeats the idea clearly and sounds natural in Danish.

The sentence could have used a pronoun in some contexts, but repeating the noun is very normal, especially when the speaker wants to be clear:

• ... men ømheden forsvinder som regel dagen efter.

This makes it explicit that it is the soreness that disappears.

Also, Danish often repeats the noun where English might more readily switch to it.

Som regel means usually, generally, or as a rule.

In the sentence:

• ømheden forsvinder som regel dagen efter

it modifies the whole statement and fits naturally after the verb:

• forsvinder som regel

This placement is very common in Danish.

Compare:

• Jeg træner som regel om morgenen. = I usually train in the morning.
• Han kommer som regel til tiden. = He usually arrives on time.

You may also hear it in other positions, but the position used here is very standard.

Dagen efter is a set expression meaning the next day or the day after.

So:

• dagen efter = the following day
• aftenen efter = the following evening
• ugen efter = the following week

This is just the natural Danish order in this expression.

By contrast, efter dagen would literally mean after the day, which is usually not what you want here.

Not exactly, even though the basic idea is related.

• In Efter træningen, efter is a preposition meaning after:

  • after the workout

• In dagen efter, efter acts more like an adverb/post-position in a fixed time expression:

  • the day after / the following day

So the meaning is connected, but the grammar is a bit different.

Because Danish often uses the present tense for things that happen regularly or are generally true.

Here the sentence means something like:

• After training, my muscles hurt, but the soreness usually goes away the next day.

This is not one single future event; it is a habitual pattern. So present tense is completely natural:

• ømheden forsvinder som regel dagen efter

English does the same in many similar cases:

• I get sore after workouts, but it usually goes away the next day.

In this context, træningen is very naturally understood as the workout or the training session.

The noun træning can mean:

• training in general
• exercise
• a workout/session

So:

• Efter træningen can be translated as After the workout
• or After training, depending on context

Even though the Danish form is definite, English may choose either a definite translation or a more natural general one.

Yes, but the nuance is slightly different.

• Jeg har ondt i musklerne = My muscles hurt / I have pain in my muscles
• Jeg er øm i musklerne = My muscles are sore / I am sore in my muscles

The second version emphasizes soreness more specifically, while have ondt is broader and can describe pain in general.

In exercise contexts, both can work, but they are not perfectly interchangeable.

Because men means but and joins two main clauses here:

• Efter træningen har jeg ondt i musklerne
• ømheden forsvinder som regel dagen efter

In standard Danish punctuation, clauses joined by men are separated by a comma.

So the comma is normal and expected here.