Here is the problem I took from Oxford English Grammar by Swan.
Read the text and answer the questions. Use past perfect progressive!
…. Rebecca went horse-riding …
Who was wearing high boots and a hard hat? Why?
The key answer only gives me one answer i.e
Rebecca, because she had been horse-riding.
Now, I'm questioning why they omitted "going". It's clear on the text Rebecca went horse-riding. Then why isn't it
Rebecca, because she had been going horse-riding.*
As you can see on the screenshot, the e-book marked my answer wrong. Usually the e-book gives the alternative answer like when I write I've and I have will be accepted.
My reason I ask this is because I'm familiar with the construction Go+gerund. For example a sentence I took from Understanding and Using English Grammar by Azar:
He finished the day by going dancing with some of his friends.
Best Answer
Interesting question. I think the expression "go [verb]ing", where the verb is a sport or leisure activity, has a suggestion of "go to the place where such an activity happens". Rebecca spent the afternoon riding, not going to the stables. The author could have said that Roger 'went swimming', but he only went to the pool once, so he spent that half-hour swimming, not going swimming.