Handleggurinn minn er þreyttur eftir líkamsræktina.

Handleggurinn means the arm. The ending -inn is the definite article in Icelandic, attached to the noun itself.

• handleggur = arm
• handleggurinn = the arm

In this sentence, Icelandic uses the arm my rather than English-style my arm, so the noun is definite.

In Icelandic, possessives like minn (my) often come after the noun, especially when the noun already has the definite article.

So:

• handleggurinn minn = literally the arm mine
• natural English: my arm

This is a very common Icelandic pattern:

• bíllinn minn = my car
• húsið mitt = my house

The possessive must agree with the noun in gender, number, and case.

handleggur is:

• masculine
• singular
• here in the nominative

So the correct form is minn.

Compare:

• masculine singular nominative: minn
• feminine singular nominative: mín
• neuter singular nominative: mitt

Example:

• handleggurinn minn = my arm
• bókin mín = my book
• húsið mitt = my house

Because the adjective must agree with the subject, just like the possessive does.

Here, the subject is handleggurinn minn, which is:

• masculine
• singular
• nominative

So the adjective takes the masculine singular nominative form:

• þreyttur = tired (masculine singular)
• þreytt = tired (neuter singular)
• þreytt or þreyttur/þreyttir depending on form and context for other patterns

So:

• Handleggurinn minn er þreyttur = My arm is tired

Er is the present tense of vera, the Icelandic verb to be.

So:

• er = is

The structure is very similar to English:

• Handleggurinn minn = my arm
• er = is
• þreyttur = tired

So the sentence structure is basically: My arm is tired ...

Here eftir means after.

In this sentence, eftir takes the accusative case, which is why you get líkamsræktina.

So:

• eftir líkamsræktina = after the workout / after the gym session

Many Icelandic prepositions require specific cases, so it is useful to learn them together with the preposition.

Because eftir here requires the accusative, and the noun is also definite.

Breaking it down:

• líkamsrækt = exercise / fitness training / workout
• líkamsræktin = the workout / the exercise (nominative definite)
• líkamsræktina = the workout (accusative definite)

So after eftir, Icelandic uses líkamsræktina.

It depends on context. Líkamsrækt literally refers to physical exercise / fitness training, but in everyday use it can sometimes also refer to going to the gym or a workout session.

So eftir líkamsræktina could be understood as:

• after the workout
• after exercise
• sometimes loosely after the gym

The exact English translation depends on the context the sentence appears in.

This sentence uses a very straightforward Icelandic word order:

• Handleggurinn minn = subject
• er = verb
• þreyttur = complement
• eftir líkamsræktina = prepositional phrase

So it follows a pattern close to English: My arm is tired after the workout.

Even though Icelandic can have more flexible word order than English, simple statements like this often look quite familiar.

Yes, but it would usually sound different in tone and is less neutral in everyday use.

• Handleggurinn minn er þreyttur is the most natural everyday way to say my arm is tired.
• Minn handleggur er þreyttur is grammatically possible, but it sounds more emphatic or contrastive, something like my arm is tired (as opposed to someone else’s, or another body part).

So for normal everyday speech, handleggurinn minn is the safer choice.

Yes, handleggur is a masculine noun. That matters because it affects:

• the form of the article: handleggurinn
• the possessive: minn
• the adjective: þreyttur

A big part of learning Icelandic is getting used to noun gender, because other words in the sentence often have to match it.

Not directly. This sentence specifically says that the arm is tired:

• Handleggurinn minn = my arm
• er þreyttur = is tired

If you wanted to say I am tired, you would say:

• Ég er þreyttur if the speaker is male
• Ég er þreytt if the speaker is female

So this sentence focuses on the body part, not the whole person.