Article

Kendall suggests testing the rotator cuff muscles in
their maximally shortened position, since one-joint muscles are thought to be
strongest. We found little evidence to support this concept. The purpose of this
study was to determine if the shoulder internal rotator (IR)
and external rotator
(ER) muscles are strongest when placed in their shortened length position.
METHODS: Fifty-three subjects participated. Glenohumeral joint internal rotation
and external rotation motion was measured. Muscle strength was then tested using
a hand-held dynamometer in four positions: (1) end-range ER; (2) neutral 0
degrees ; (3) glenohumeral joint mid-range and (4) end-range IR. Data were
analyzed using two repeated measures ANOVA's. RESULTS: The results suggest that
rotator muscle strength is dependent on muscle length. IR strength was weakest at
end-range IR in its shortest length; ER muscle strength was weakest at end-range
ER in its shortest length. Muscle strength of the IR or ER was not significantly
different when comparing neutral 0 degrees to the mid-range position and at their
most lengthened position. CONCLUSION: The IR and ER muscles were found to be
weakest when placed in a position of shortest muscle length, while the neutral 0
degrees and mid-range positions were the strongest positions.

Langue : ANGLAIS