Thank you for your reply.
In this case I'm not using canonicals, because I want this page to rank individually for it's specific keyword 'Sport shoes'.
In my point of view the content is quite different. But of course I don't know how Google is understanding it.
What I did a few weeks back: From the product 'Sport shoes' I set an internal link with the anchor text 'Shoes' back to the category page. Unfortunately, this didn't work either.
