Breakdown of Я купил кроссовки для прогулок, потому что в старой обуви мне неудобно ходить.
Questions & Answers about Я купил кроссовки для прогулок, потому что в старой обуви мне неудобно ходить.
Купил is the perfective past form of купить, so it presents the action as completed: I bought.
That fits this sentence because the speaker is talking about a finished result: they now have the sneakers.
If you used покупал, it would sound more like:
- the process of buying,
- a repeated action,
- or background information in some contexts.
So here:
- Я купил кроссовки = I bought sneakers / I bought a pair of sneakers
Also, купил tells you the speaker is grammatically masculine singular. A woman would say купила.
In Russian, items that normally come in pairs are very often named in the plural:
- кроссовки = sneakers
- ботинки = boots/shoes
- брюки = trousers
- ножницы = scissors
So Я купил кроссовки is the normal way to say I bought sneakers / a pair of sneakers.
If you want to be extra explicit, you can say:
- пару кроссовок = a pair of sneakers
But in everyday Russian, just кроссовки is completely natural.