Performance
Does Strength Training Make You Faster?
The mechanism is running economy, not raw power. What that means in practice, how big the effect is likely to be, and where the evidence is less settled than the internet suggests.
Topic
VO2 max
Performance
Heart Rate Zones: What They Are Actually For
Zones are a way of keeping easy runs easy. They are a poor way of measuring how hard a hard run was. Knowing which job you are asking them to do fixes most of the confusion.