Don't focus too much on the keywords. Creating good content should be your main focus because you never know under which keyword your post will be ranked. You can write a post for "Choosing the Best Running Shoes" but get ranked under "Best Running Shoes". You never know.

buying the best running shoes for you

Best running shoes is kinda broad.

Choosing the best running shoes is more specific, in fact the longer the keyword phrase, the more specific it is generally.

I would create a post on Choosing the best running shoes.

I would then consider creating posts around these keywords and then link them back to Choosing the best running shoes, since they relate to that topic.

You can also link out to them from this page where it makes sense.

best running shoes for men
best running shoes for bad knees
best rated running shoes
best running shoes for flat feet
best running shoes for women
best running shoes for overpronation
best running shoes for high arches

Linking internally to your content will help with rankings.

Use the alphabet soup technique to find more of these kind of keywords and keep creating content.

Hope that helps.

Best,
Frank

Good advice given here, folks!

You know how when you search for something in Google and you will see the keywords highlighted under the url? If not search for something and then you will notice. The keywords can be spread throughout the site or description so your keyword should be great for both. I hope that made sense.

Always try to get some "low hanging fruit" keywords - they will rank much better, and you will get the traffic.

Keywords - that title should cover both!

Yes both are fine with your title.