What Research is There?

A number of studies have suggested a relationship between the vertical position of the jaw and isometric strength of the upper extremities and cervical flexors (e.g Abdallah et al. "Affecting upper extremity strength by changing maxillomandibular vertical dimension in deep bite subjects", The Journal of Craniomandibular Practice (2004); 22: 268-275.

Chelette, Tripp et al. concluded that a properly-fitted MORA "can be of assistance to some individuals during execution of the antiG straining manouver" in a study of active-duty military personnel - "Effects on G Tolerance while biting down on a ...(MORA), Oct. 1990, Harry G. Armstrong Aerospace Medical Research Laboratory.

Quite importantly, Chafka et al. concluded that there is a vertical position, UNIQUE TO EACH INDIVIDUAL, which maximizes isometric strength , "The Effect of Stepwise Increases in Vertical Dimension of Occlusion on Isometric Strength of Cervical Flexors and Deltoid Muscles in Nonsymptomatic Females", The Journal of Craniomandibular Practice (2002), 20:264-273.

Bracco and other researchers at the University of Torino in 2004 published the results of their research on the "Effects of different jaw relations on postural stability in human subjects", Neuroscience Letters 356 (2004), 228-230. They looked at the effect of three different jaw relations on body posture, and concluded that a "myocentric" (neuromuscular) position improved balance on the frontal plane more so than did the other two jaw relations.

Forgione et al. concluded that a relationship does exist between bite and isometric strength, "Strength and bite, Part 2: testing isometric strength using a MORA to set a functional criterion" , The Journal of Cranio-Mandibular Practice (1992); 10(1):13-20.

Wang, Ueno, et al. found that maximum voluntary contraction during shoulder abduction was significantly stronger with a MORA, in "Influence on isometric muscle contraction during shoulder abduction by changing occlusal situation", Bull. Tokyo Med Dent Univ, 1996, 43 (1): 1- 12.

Abduljabbar et al. found that individuals with loss of vertical dimension of occlusion respond to a bite raising appliance by increased isometric strength, "Effect of increased maxillo-mandibular relationship on isometric strength in TMD patients with loss of vertical dimension of occlusion", The Journal of Craniomandibular Practice (1997) Jan; 15(1) 57-67.

al-Abassi et al. found that, in deep bite individuals,  cervical muscle isometric strength is affected by bite position and vertical dimension of occlusion, "The effect of vertical dimension and mandibular position on isometric strength of the cervical flexors", The Journal of Cranio-Mandibular Practice, (1999) Apr; 17(2):85-92.

Sakaguchi and others in 2007 reported that "changing mandibular position affected body posture, and conversely, that changing body posture affected mandibular position" (see "Examination of the Relationship Between Mandibular Position and Body Posture", The Journal of Craniomandibular Practice, (2007), 25, 237-249).

More recently, researchers at Rutgers University, in beginning the journey of extending the research to dynamic situations, compared a neuromuscular mouthguard with custom-fitted mouthguards. The studies indicate a significantly better performance of a neuromuscular mouthguard over a custom-fitted mouthguard with respect to vertical jump, peak power output, average peak power, and average mean power. (Arents et al. "Effects of a neuromuscular dentistry-designed mouthguard on muscular endurance and anaerobic power", Comparative Exercise Physiology (2010)).