This study was conducted by a colleague of mine..
J Am Diet Assoc. 1988 Jun;88(6):698-704.Applied kinesiology unreliable for assessing nutrient status. Kenney JJ, Clemens R, Forsythe KD.
Applied kinesiology is a technique used to assess nutritional status on the basis of the response of muscles to mechanical stress. In this study, 11 subjects were evaluated independently by three experienced applied kinesiologists for four nutrients (thiamin, zinc, vitamin A, and ascorbic acid). The results obtained by those applied kinesiologists were compared with (a) one another, (b) standard laboratory tests for nutrient status, and (c) computerized isometric muscle testing. Statistical analysis yielded no significant interjudge reliability, no significant correlation between the testers and standard biochemical tests for nutrient status, and no significant correlation between mechanical and manual determinations of relative muscle strength. In addition, the subjects were exposed in a double-blind fashion to supplements of thiamin, zinc, vitamin A, and ascorbic acid and two placebos (pectin and sucrose) and then re-tested. According to applied kinesiology theory, "weak" (indicating deficiency) muscles are strengthened when the subject is exposed to an appropriate nutritional supplement. Statistical analysis revealed no significant differences in the response to placebo, nutrients previously determined (by muscle testing) to be deficient, and nutrients previously determined (by muscle testing) to be adequate. Even though the number of subjects (11) and nutrients (4) tested was limited, the results of this study indicated that the use of applied kinesiology to evaluate nutrient status is no more useful than random guessing.
And a few more...
This study found "no effect"
Triano JJ. Muscle strength testing as a diagnostic screen for supplemental nutrition therapy: a blind study. Journal of Manipulative and Physiological Therapeutics 5:179-182, 1982
This double-blind trial concluded that "muscle response appeared to be a random phenomenon."
Haas M and others. Muscle testing response to provocative vertebral challenge and spinal manipulation: a randomized controlled trial of construct validity. Journal of Manipulative and Physiological Therapeutics 17:141-148, 1994.
This study showed that suggestion from the practitioner can significantly influence the outcome of muscle-testing.
Applied kinesiology - Double-blind pilot study. Journal of Prosthetic Dentistry 45:321-323, 1981.
In both these studies, several practitioners of AK were tested and the results failed to find the the testing reliable.
Ludtke R and others. Test-retest-reliability and validity of the kinesiology muscle test. Complementary Therapy in Medicine 9:141-145, 2001.
Hyman R. The mischief-making of ideomotor action. by ideomotor action. The Scientific Review of Alternative Medicine, Fall-Winter issue, 1999. Republished on Quackwatch, Aug 26, 2003.