Many trainers and instructors alike speak highly of plank exercises for core strengthening. After all, it is THE most effective way to build core stability, and reigns supreme among many other ab workouts (side note: doing 1000 crunches will NOT build a six pack).
Unlike the traditional set of core exercises, the plank works all four muscle groups within your abdominal region. This includes the rectus abdominis (the aesthetic 'six pack' abs), the transverse abdominis (deep core stabilizers), as well as the internal obliques and external obliques (ipsa/contralateral rotators and hip and back mobilizers).
Simply incorporating 30 seconds to 2 minutes (progressively) of plank every other day, trains the body to become less dependent on the overuse and hyperextension of the back muscles and lumbar extensors. This, in turn, will impact your overall posture and reduce lower back discomfort.
The core is not just limited to the abdominals at our pelvic region. The core is our powerhouse and connects to our spine, mid/upper back muscles, shoulders, glutes, etc. As the plank becomes a daily staple, your back, glutes, chest, shoulders, and neck will engage and work hard to adjust your body's normative alignment.
Here are a few pointers to keep in mind when working on this exercise. Be extremely adamant about keeping the hips and lower back neutral. Do NOT let the lower back sag, and/or let the glutes drift higher than your hips. You'll want to keep your glutes level with your hips and continue to engage your core while simultaneously squeezing your glutes for optimal form. Lastly, try not to let your head drift forward and keep your neck neutral. By 'contracting' your core, try to think of tensing your abs throughout this exercise in order to not let any tension travel to the lower back.
Lastly, aside from the mechanical benefits, practicing the plank pose also releases a neurochemical substance also known as endorphins. As you are working diligently to isometrically hold this pose, you are simultaneously receiving a chemical benefit in your brain AND getting stronger!