You might be surprised to read that I think the front plank could be considered a sort of "dumb" exercise, IF YOUR goal is to improve your durability as a runner and reduce your risk of injury.
As an endurance athlete, core stability is what you're after. Certainly, the front plank can help develop strength and endurance in the front of the body, but if your goal is to improve durability and speed, the front plank fails miserably.
Lots of people like to work on the muscles that make them look good in a bathing suit. If that's your aim, carry on.
BUT... if your mission is to create a good, solid, stable core in three planes of motion, the half front plank with a reach AND the side plank will give you a much better payoff for time and energy spent. These plank exercises challenge transverse and frontal plane motions respectively, and they are too often ignored.
In addition to this podcast, click on the image below to check out a 59-second video I did for Instagram and Facebook, where I show you one other, different but much more productive way to train core stability!
To your success,