Paavolonein did a study looking at explosive training and running economy. The biggest problem with the study besides small sample size was no control group.
The runners in the study were orienteers, but their 5K times were around 17 minutes or so which is not national class, but not walking either.
Meb and Deena have done some explosive lifting. Anecdotal I know, but should be of interest.
I would say traditional lifting for someone already trained is probably not going to help a lot unless there is some big specific issue involved.
You state lifting is important (I would agree from a general health standpoint) and can improve performance without one iota of support or proof.