Isometric Contractions and the Plank If you've ever seen a mime trying to escape his invisible box, you've seen a playful example of an isometric contraction. Isometric exercises are strength-training exercises that involve the contraction of a muscle against an immovable resistance. While the mime's resistance is imaginary, you use the floor for resistance when doing an isometric plank. The isometric plank exercise provides core stability, improves posture and protects your lower back. Same Length “Iso” means same and “metric” means length, so isometric literally means “same length.” The static tension of isometric exercise strengthens the muscles at the same length -- in the position in which they are held. This can be beneficial when rehabilitating an injured joint or as a technique to improve fluid movement by overcoming weaknesses within a range of motion. It's also a good exercise technique for training the core muscles, which often must remain stable as your arms and legs move. Because isometric exercises don't move the joint through a full range of motion, you should hold isometric contractions in various positions and at varying angles to obtain maximum benefit. Muscles Worked To safely maintain the plank pose, you have to pull your belly button up toward your spine. This action, called abdominal hollowing, activates the deeper, stabilizing muscles of the core. The muscles that benefit most from an isometric plank are the transverse abdominis, obliques, rectus abdominis and erector spinae. Depending on the position you hold, the plank pose may also strengthen muscles in your wrists, arms, shoulders, chest, feet, legs and buttocks. Back Support Support for your back requires stability throughout the core. Many people who suffer from chronic lower-back pain have weak core abdominal muscles. The deepest abdominal muscles, the transverse abdominis, stabilizes the lower back before 1 | P a g e movement of your arms and legs occurs. This function is critical to avoid excessive or unnatural movement of the joints in your lower back. You contract this muscle when you hollow your abdominals in the plank pose. The inability to maintain an isometric contraction of this muscle leads to poor posture and overuse of other muscles, which can cause back pain. Regular training of the core, including doing the isometric plank exercise, can help overcome these imbalances. Erector Spinae Group 2 | P a g e Muscles Engaged During Isometric (Static) Plank Moving and Pushing Weights Before Building Core Strength and Stability The Vacuum The vacuum exercise is an exercise which involves contracting some internal abdominal muscles, primarily the transverse abdominal muscle, and not as much the diaphragm. Repetitions of the exercise may be used as a form of endurance training, and light strength training. There is difficulty building strength in the muscle, as it is not easy to apply resistance training to the deeper internal muscles. The reasons for performing this exercise vary. It has been done for aesthetic purposes in bodybuilding competitions (to suck the abdomen in, making it appear less bulgy). It can be done to enhance overall core stability and strength. It is used in belly dance to actively perform flutters, 3 | P a g e engaging various fibres in the muscle selectively. Some believe the pressures it exerts upon the intestines are an aid to digestion. It is used in reverse breathing upon exhalation. In performing a vacuum (activating the transverse abdominis), one draws one's bellybutton inward, toward the spine. Some perform a vacuum in conjunction with bending over, reaching overhead, or when lifting heavy weights, although the benefit and healthiness of this is disputed (some advocated just tensing the midsection, with primary focus more so on the lower back). Increasing the range of motion (how far it is drawn in), the intensity (very little can be done, other than resisting gravity) or the duration are the methods of making the muscles stronger. Performing flutters or Tabata intervals of high intensity and rest similar to Kegel is also common. 4 | P a g e .