The plank exercise is an isometric core exercise that involves maintaining a position similar to a push-up for the maximum possible time.
- Plank exercise can activate core muscles with low compressive forces (1600 to 1800N) avoiding high compressive forces on the lumbar vertebrae, which occur in back extension, trunk curls or lying prone with extended arms and legs
- During the plank exercise the aim is to try and maintain a neutral spine against the forces acting on it. Gravity poses a downward force on the elevated trunk, while the contact points on the ground (toes and forearms) counteract the downward force with an upward force, this results in the trunk wanting to “dip.”. For correct form it is essential that the core muscles, especially the abdominal muscles, activate to resist the downward force and potential dipping to ensure the spine remains in neutral.
- Due to the fact that serratus anterior is attached to your abdominal muscles the serape effect is evident when performing the plank exercise; the effect causes increased activation of the serratus anterior.
Key Points for Proper Execution
- It has been demonstrated that doing isometric dorsiflexion during plank exercise causes increased activation of the abdominal muscles compared to isometric planterflexion
- Abdominal muscles are attached to adductors by a sling called anterior oblique sling. Doing unilateral isometric hip adduction results in increased activation of the abdominal muscles compared to bilateral isometric hip adduction
- Attentional focus on abdominal muscles (upper or lower abdominal), during this exercise, has shown increased activation of the abdominal muscles compared to not focusing on the abdominal muscles 
- James W, Kendra C, Erin E, Stephanie D, Nicole L. John H. Hollman. Magnitudes of muscle activation of spine stabilizers in healthy adults during prone on elbow planking exercises with and without a fitness ball. Physiotherapy Theory and Practice.2018:34:
- Choi JH, Kim DE, Cynn H. Comparison of Trunk Muscle Activity Between Traditional Plank Exercise and Plank Exercise With Isometric Contraction of Ankle Muscles in Subjects With Chronic Low Back Pain. Journal of Strength and Conditioning Research.May 2019. 1064-8011
- Soo YK, Min HK, Eui RK, In GJ, Eun YS, Jae SO. Comparison of EMG activity on abdominal muscles during plank exercise with unilateral and bilateral additional isometric hip adduction. Journal of Electromyography and Kinesiology. 2016 :30: 9-14.
- Calatayud J, Casaña J, Martín F, Jakobsen MD, Andersen LL, Colado JC. Electromyographic Effect of Using Different Attentional Foci During the Front Plank Exercise. American Journal of Physical Medicine & Rehabilitation. 2019: 98(1):26-29.