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Timothy L. Uhl, Thomas Rice, Brianna Papotto, and Timothy A. Butterfield

Context:

The role of the rotator cuff is to provide dynamic stability to the glenohumeral joint. Human and animal studies have identified sarcomerogenesis as an outcome of eccentric training indicated by more torque generation with the muscle in a lengthened position.

Objective:

The authors hypothesized that a home-based eccentric-exercise program could increase the shoulder external rotators’ eccentric strength at terminal internal rotation (IR).

Design:

Prospective case series.

Setting:

Clinical laboratory and home exercising.

Participants:

10 healthy subjects (age 30 ± 10 y).

Intervention:

All participants performed 2 eccentric exercises targeting the posterior shoulder for 6 wk using a home-based intervention program using side-lying external rotation (ER) and horizontal abduction.

Main Outcome Measures:

Dynamic eccentric shoulder strength measured at 60°/s through a 100° arc divided into 4 equal 25° arcs (ER 50–25°, ER 25–0°, IR 0–25°, IR 25–50°) to measure angular impulse to represent the work performed. In addition, isometric shoulder ER was measured at 5 points throughout the arc of motion (45° IR, 30° IR, 15° IR, 0°, and 15° ER). Comparison of isometric and dynamic strength from pre- to posttesting was evaluated with a repeated-measure ANOVA using time and arc or positions as within factors.

Results:

The isometric force measures revealed no significant differences between the 5 positions (P = .56). Analysis of the dynamic eccentric data revealed a significant difference between arcs (P = .02). The percentage-change score of the arc of IR 25–50° was found to be significantly greater than that of the arc of IR 0–25° (P = .007).

Conclusion:

After eccentric training the only arc of motion that had a positive improvement in the capacity to absorb eccentric loads was the arc of motion that represented eccentric contractions at the longest muscle length.

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Alon Rabin, Brakha R. Tabi, Timothy L. Uhl, and Zvi Kozol

Context: Decreased scapular upward rotation (UR) and diminished activation of the serratus anterior (SA) and lower trapezius (LT) are often observed among patients with subacromial impingement syndrome. Maintaining the elbow fully flexed during shoulder flexion may limit glenohumeral motion due to passive insufficiency of the triceps brachii and therefore facilitate greater scapular UR and increased scapular muscle activation. Objectives: To compare scapular UR, SA, upper trapezius (UT), middle trapezius, and LT activation levels between shoulder flexion with the elbow extended (Flexion-EE) to shoulder flexion with the elbow fully flexed (Flexion-EF). This study hypothesized that Flexion-EF would result in greater scapular UR, greater SA and LT activation, and a lower UT/SA and UT/LT activation ratio compared with Flexion-EE. Design: Cross-sectional study. Setting: A clinical biomechanics laboratory. Participants: Twenty-two healthy individuals. Main Outcome Measures: Scapular UR and electromyography signal of the SA, UT, middle trapezius, and LT, as well as UT/SA and UT/LT activation ratio were measured during Flexion-EE and Flexion-EF. Results: Flexion-EF resulted in greater scapular UR compared with Flexion-EE (P < .001). Flexion-EF resulted in greater SA activation, lower UT activation, and a lower UT/SA activation ratio compared with Flexion-EE (P < .001). Conclusions: Fully flexing the elbow during shoulder flexion leads to increased scapular UR primarily through greater activation of the SA. This exercise may be of value in circumstances involving diminished scapular UR, decreased activation of the SA, and an overly active UT such as among patients with subacromial impingement syndrome.

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Kevin R. Ford, Gregory D. Myer, Laura C. Schmitt, Timothy L. Uhl, and Timothy E. Hewett

The purpose of this study was to identify alterations in preparatory muscle activation patterns across different drop heights in female athletes. Sixteen female high school volleyball players performed the drop vertical jump from three different drop heights. Surface electromyography of the quadriceps and hamstrings were collected during the movement trials. As the drop height increased, muscle activation of the quadriceps during preparatory phase also increased (p < .05). However, the hamstrings activation showed no similar increases relative to drop height. Female athletes appear to preferentially rely on increased quadriceps activation, without an increase in hamstrings activation, with increased plyometric intensity. The resultant decreased activation ratio of the hamstrings relative to quadriceps before landing may represent altered dynamic knee stability and may contribute to the increased risk of ACL injury in female athletes.

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Jennifer Stiller and Timothy L. Uhl

Column-editor : Carl G. Mattacola

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Shelby E. Baez, Johanna M. Hoch, and Timothy L. Uhl

Clinical Question:

Is there evidence to suggest intermittent cervical traction with cervical and scapular strengthening exercises is more effective in decreasing neck and arm pain when compared with cervical and scapular strengthening exercises alone in nonoperative patients with cervical radiculopathy?

Clinical Bottom Line:

There is currently inconsistent, high-quality evidence that suggests that the use of intermittent cervical traction in addition to strengthening exercises is more effective at decreasing pain in nonoperative patients with cervical radiculopathy when compared with strengthening alone. Future research should continue to examine long-term outcomes associated with cervical radiculopathy patients who use intermittent cervical traction as an intervention.

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Brianna M. Papotto, Thomas Rice, Terry Malone, Timothy Butterfield, and Tim L. Uhl

Context: Shoulder external rotators are challenged eccentrically throughout the deceleration phase of throwing, which is thought to contribute to overuse injuries. To evaluate the effectiveness of intervention programs, as well as identifying deficits, reliable and responsive measures of isometric and eccentric shoulder external rotation are necessary. Previously, isometric measures have primarily tested a single position, and eccentric measures have not been found to have high reliability. Objective: To examine the between-days reliability of multiple-angle isometric and dynamic eccentric isokinetic testing of shoulder external rotation. Design: Repeated measures. Participants: 10 healthy subjects (age 30 ± 12 y, height 166 ± 13 cm, mass 72 ± 10 kg). Main Outcome Measures: Average isometric peak torque of shoulder external rotation at 7 angles was measured. From these values, the angle of isometric peak torque was calculated. Dynamic eccentric average peak torque, average total work, and average angle of peak torque were measured. Results: Between-days reliability was high for average peak torque during isometric contractions at all angles (ICC ≥ .85), as it was for dynamic eccentric average peak torque (ICC ≥ .97). The estimated angle of isometric peak torque (ICC ≤ .65) was not highly reliable between days. The average angle of peak torque from the eccentric testing produced inconsistent results. Average total work of dynamic eccentric shoulder external rotation was found to be highly reliable between days (ICC ≥ . 97). Conclusion: Aspects of force such as peak torque and total work in isometric and eccentric testing of the shoulder external-rotator muscles can be measured reliably between days and used to objectively evaluate shoulder strength and identify changes when they occur. Angle measurements of peak torque could provide insight into the mechanical properties of the posterior shoulder muscles but were found to be inconsistent between days.

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Aaron D. Sciascia, Arthur J. Nitz, Patrick O. McKeon, Jennifer Havens, and Timothy L. Uhl

Athletic preinjury function is typically determined via subjective recall; however, obtaining preinjury function before injury occurs should be attempted in order to establish an individual baseline for postinjury comparison. The purpose of this study was to obtain preinjury baseline values for the Foot and Ankle Disability Index (FADI) and Foot and Ankle Disability Index sport version (FADISP), single-leg hop for distance, and Star Excursion Balance Test anterior reach and determine if athletes returned to those values following ankle injury. Out of 41 qualifying injuries, FADI/FADISP scores were significantly reduced at initial injury compared with baseline and all other time points (p < .001) but recovered by discharge. Single-leg hop and Star Excursion Balance Test recovered to baseline values by the discharge time point (p ≥ .98). Subjective and objective preinjury function can be reestablished by discharge from supervised treatment following low-grade ankle injury and maintained for at least 6 months following the cessation of treatment. However, testing metrics should be reviewed on an individual athlete basis, because group data may mask individual patient needs.

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Aaron D. Sciascia, Arthur J. Nitz, Patrick O. McKeon, Jennifer Havens, and Timothy L. Uhl

Athletic preinjury function is typically determined via patient recall, however obtaining preinjury function before injury occurs should be attempted. The purpose of this study was to obtain preinjury physical function baseline values using the Knee Injury and Osteoarthritis Outcome Score (KOOS), single-leg hop for distance (SLH), and Star Excursion Balance Test (SEBT) anterior reach to determine if athletes return to those baseline values following knee injury. Out of 27 qualifying injuries, KOOS scores were significantly reduced at initial injury compared to baseline and all follow-up points (p ≤ .02). In most instances, baseline KOOS scores were not met at the discharge time point. SLH and SEBT recovered to baseline values by discharge. Injury severity and previous injury created variations in KOOS scores across multiple time points. Subjective and objective preinjury function can be re-established following knee injury but recovery may not occur at discharge from rehabilitation.