Learn Turkish: Hamal oflaya oflaya yukarı çıktı. - The mover went upstairs, huffing and puffing.

The root is ofla- (to groan or sigh). Because it ends in a vowel, we add the buffer letter y before the -a suffix, making it oflaya. Repeating it shows that the mover was continuously huffing and puffing the whole time he was climbing.

Is oflamak related to the exclamation 'of'?

Yes! It literally comes from the common Turkish exclamation of (used for exhaustion, frustration, or relief). The suffix -la turns the sound into the verb oflamak, meaning to make that sighing or groaning sound.

Could I use oflayarak instead of oflaya oflaya here?

Yes, oflayarak (using the -(y)arak suffix) also means doing the action while huffing. But using the repeated -(y)a form emphasizes the continuous, repetitive nature of his struggle all the way up the stairs.

Why doesn't yukarı take the dative case (as in yukarıya) since he is going to a place?

Direction words like yukarı (up), aşağı (down), içeri (inside), and dışarı (outside) can act directly as adverbs of motion. While yukarıya çıktı is grammatically fine, dropping the dative suffix is very common and natural when describing a direction of movement rather than a specific destination point.