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  • Author: James M. Rankin x
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W. Steven Tucker, Charles W. Armstrong, Erik E. Swartz, Brian M. Campbell and James M. Rankin

Context:

Closed kinetic chain exercises are reported to provide a more functional rehabilitation outcome.

Objective:

To determine the amount of muscle activity in 4 shoulder muscles during exercise on the Cuff Link.

Design:

Repeated measures.

Setting:

Laboratory.

Subjects:

10 men and 10 women, age 18–50.

Intervention:

Subjects performed 3 sets of 5 revolutions on the Cuff Link in non-weight-bearing, partial-weight-bearing, and full-weight-bearing positions.

Main Outcome Measures:

Electromyography data were collected from the upper trapezius, anterior deltoid, serratus anterior, and pectoralis major and were expressed as percentage of maximal isometric contractions.

Results:

Significant differences were found across the weight-bearing conditions for all 4 muscles. Exercise on the Cuff Link required minimal to significant amounts of muscle recruitment.

Conclusions:

Muscle recruitment increases as weight bearing increases during use of the Cuff Link, suggesting an increase in dynamic stabilization of the glenohumeral joint.

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Nicole M. Livecchi, Charles W. Armstrong, Mitchell L. Cordova, Mark A. Merrick and James M. Rankin

Objective:

To compare average electromyogram (EMG) activity of the vastus medialis obliquus (VMO) and vastus lateralis (VL) during straight-leg raise (SLR) and knee extension (KE) with the hip in neutral and lateral rotation.

Design:

1 × 4 factorial repeated-measures.

Setting:

Laboratory.

Participants:

13 male college students.

Intervention:

SLR with hip flexed at 40°, in neutral position, and maximally laterally rotated and KE with hip in neutral and maximally laterally rotated.

Main Outcome Measure:

Average EMG activity during each of the 4 conditions, normalized against peak muscle activity during that trial.

Results:

No differences were observed between exercises in VMO activity (F 3,36 = 0.646, P > .05), VL activity (F 3,36 = 1.08, P > .05), or VMO:VL ratio (F 3,36 = 0.598, P > .05).

Conclusions:

Electrical activity of the VMO or VL and VMO:VL ratio do not change with hip position or exercise.