Intraexaminer comparison of applied kinesiology manual muscle testing of varying durations: a pilot study

The purpose of this study is to investigate the difference in results (strong/facilitated vs weak/functionally inhibited) between short (1 second) and long (3 seconds) manual muscle tests (MMTs) on the same subject and to pilot the use of thin-film force transducers for characterizing the parameters of MMT and for measuring maximum voluntary isometric contraction (MVIC).

Forty-four healthy chiropractic students were tested. A thin-film force transducer recorded force over time during MVIC of the middle deltoid and 1- and 3-second MMTs of the same subjects. The MMTs were graded as strong (able to resist the testing pressure) or weak (unable to resist testing pressure, breaking away).

Forty-two short tests were strong, and 2 were weak. Thirty-nine long tests were strong, and 5 were weak. κ (0.54) showed fair agreement for results between short and long tests. Peak force in both short and long weak tests was higher than that in strong tests when expressed as a proportion of maximum contraction. All manual tests used less force than MVICs.

This study demonstrated that a study of this nature is feasible. Longer test durations demonstrate some muscle weaknesses that are not evident on 1-second MMTs. Thin-film transducers show promise for recording MMT parameters for research purposes.