End Range Eccentric Antagonist/Concentric Agonist Strength Ratios: A New Perspective in Shoulder Strength Assessment

Abstract

he use of isokinetic dynamometers to analyze the strength of the shoulder rotator cuff muscles in overhead athletes has provided valuable information for the evaluation, rehabilitation, and conditioning of these athletes. Numerous test positions and speeds of testing have been described to improve sports specificity and identify test p e sitions which best measure strength for each muscular activity (1,(3)(4)(5)(6)8,9, 16,18,20). The greatest values for lateral rotator strength have been reported with testing in the scapular plane or 90" of forward flexion (8), while testing in the neutral position has produced the greatest values for the medial rotators (l6,18). Testing in the seated position, with the shoulder abducted to 90" and the elbow flexed to 90" (parallel to the horizontal plane), has been recommended because the subject is easily stabilized, and this position closely a p proximates the position of the arm during the late cocking phase of throwing. However, this position may produce symptoms in some patients, limiting maximal effort and affecting test results. For this reason, some evaluators have recommended alternate test positions (3).Most studies have focused on the concentric strength of the shoulder

Posterior shoulder tightness and rotator cuff strength assessments in painful shoulders of amateur tennis players

“…When significant differences were observed, the analysis was complemented by the Tukey test. Before these analyses, the strength data were normalised by body mass and also measured in kilograms using the following formula: (kg strength/kg body weight) × 100 27 .…”

Assessment of agonist–antagonist shoulder torque ratios in individuals with paraplegia: a new interpretative approach

“…For the U/Es, this method has been proposed, to better evaluate the relationship between shoulder rotators. [16][17][18] Ng et al 19 and more recently Yildiz et al 18 used this eccentricconcentric approach to report torque ratios over an angular section (terminal range) where the antagonist muscles played a decelerator role (eccentric contractions). For these authors, this method is well adapted for investigating shoulder dynamic stability, especially among athletes performing overhead tasks (that is, throwing).…”

Angle Specific Analysis of Side-to-Side Asymmetry in the Shoulder Rotators

“…Greater repetitive use of the preferred arm in throwing actions in recreational and sporting activities may explain our asymmetry results [2,21]. However, previous studies have used a variety of different speeds in order to provide sport specific information about strength imbalance and injury risk in the shoulder rotators [3,4,9]. The use of a single velocity to describe angle specific strength is a limitation of our study.…”

“…The beginning shoulder ROM (cocking phase) is critical in overhead activities due to full external rotation, and superior and anterior forces being applied to the shoulder; while the end ROM (deceleration phase) requires the arm to be stopped in a short period of time from high velocities [3,4,9]. These points of the ROM have been suggested as where most imbalances may occur, leading to shoulder muscle and ligament injuries [3,4,9].…”

“…In addition, a few studies have opted to use 5°, 10°, 15° or end of ROM angle specific torque (AST) intervals for a more accurate estimation of unilateral dynamic muscle balance of the knee or shoulder joints [1,3,4,[6][7][8][9]. Dehail et al [7] demonstrated there was a significant progressive decline of flexion/extension and abduction/adduction AST strength ratios as the shoulder progressed to flexion and abduction, respectively.…”