What about isometric strength training for runners?

Isometric training involves contracting your muscles without any change in joint angle or muscle length (e.g., holding a plank or a wall sit).

The current scientific evidence on its effectiveness for improving running economy (RE) is mixed:

• Some reviews find no significant benefit compared to other methods.

• Other research suggests it's an emerging area with potential, possibly even yielding greater RE improvements than plyometrics in some situations. It might be particularly useful during periods of very high overall training load, as it can generate high muscular tension with potentially less systemic fatigue or muscle damage than dynamic heavy lifting or high-impact plyometrics.

More research is needed to determine the optimal ways to use isometric training for runners.