Intervalløkten begynner etter oppvarmingsjoggen.

Because Norwegian forms compound nouns very freely. What English often writes as two or more words, Norwegian often writes as one:

• intervall + økt = intervalløkt
• oppvarming + jogg = oppvarmingsjogg

Then the definite ending is added:

• intervalløkten = the interval session/workout
• oppvarmingsjoggen = the warm-up jog

This is very normal in Norwegian, and writing them as separate words would usually look wrong.

The ending -en marks the definite singular for many Norwegian nouns. In other words, it often means the.

So:

• en intervalløkt = an interval session
• intervalløkten = the interval session

and:

• en oppvarmingsjogg = a warm-up jog
• oppvarmingsjoggen = the warm-up jog

Unlike English, Norwegian often puts definiteness at the end of the noun instead of using a separate word like the.

Because Norwegian usually expresses definiteness with a suffix attached to the noun:

• økten = the session
• joggen = the jog

So Intervalløkten begynner etter oppvarmingsjoggen already includes the twice, built into the nouns themselves.

A separate determiner is only added in certain situations, especially with adjectives:

• økten = the session
• den lange økten = the long session

Begynner is the present tense of begynne (to begin / to start).

Examples:

• å begynne = to begin
• begynner = begins / is beginning

Norwegian verbs do not change according to person:

• jeg begynner
• du begynner
• han/hun begynner
• vi begynner

So the same present-tense form is used for everyone.

Etter means after.

In this sentence, it introduces the thing that happens first:

• etter oppvarmingsjoggen = after the warm-up jog

It is a very common preposition and is followed here by a noun phrase.

Compare:

• før treningen = before the training/workout
• etter treningen = after the training/workout

In this sentence, the speaker is referring to a specific interval session and a specific warm-up jog, so the definite forms sound natural:

• Intervalløkten = the interval session
• oppvarmingsjoggen = the warm-up jog

You might see an indefinite form in a more general statement, but here the definite form is the most natural because it sounds like part of a known training plan:

• Intervalløkten begynner etter oppvarmingsjoggen.

That suggests a particular sequence: first the warm-up jog, then the interval session.

Yes, økt is very common in exercise and training contexts. It means something like:

• session
• workout
• training session

So intervalløkt is literally an interval session/workout.

You will see økt in many compounds:

• treningsøkt = training session
• løpeøkt = running session
• styrkeøkt = strength session

This is a very productive pattern in Norwegian.

Yes. Norwegian often allows the time phrase to come first, but then the verb must come before the subject because of the V2 rule.

Original:

• Intervalløkten begynner etter oppvarmingsjoggen.

Also correct:

• Etter oppvarmingsjoggen begynner intervalløkten.

Notice the difference:

• normal order: subject + verb + adverbial
• when the sentence starts with Etter oppvarmingsjoggen, the verb begynner comes next

You would not normally say:

• Etter oppvarmingsjoggen intervalløkten begynner. ❌

The letter ø is a separate Norwegian vowel, not just an o with a mark on it.

In økt, the ø is somewhat similar to the vowel in French deux or German schön, if you know those. There is no exact English equivalent.

A rough guide:

• shape your lips as if saying o
• but try to place your tongue more like an e sound

So økt is definitely not pronounced like English okt.

Jogg is a noun meaning jog or jogging run. It is commonly treated as a common-gender noun, so the pattern is:

• en jogg
• joggen

That is why oppvarmingsjoggen ends in -en.

The full structure is:

• oppvarming = warming up
• jogg = jog
• oppvarmingsjogg = warm-up jog
• oppvarmingsjoggen = the warm-up jog

Yes. It sounds natural, especially in a fitness, coaching, or sports context.

It has a clear and normal structure:

• Intervalløkten = subject
• begynner = verb
• etter oppvarmingsjoggen = time relation / prepositional phrase

It sounds like something a coach, runner, or training app might say.