ejercicios basados en la evidencia escapulotoracicos y glh

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  • journal of orthopaedic & sports physical therapy | volume 39 | number 2 | february 2009 | 105

    [ CLINICAL COMMENTARY ]

    1Coordinator of Rehabilitation Research and Education, Department of Orthopedic Surgery, Division of Sports Medicine, Massachusetts General Hospital, Boston, MA; RehabilitationCoordinator/Assistant Athletic Trainer, Boston Red Sox Baseball Club, Boston, MA. 2Professor, Department of Physical Therapy, California State University, Sacramento, Sacramento,CA. 3Clinical Director, Champion Sports Medicine, Director of Rehabilitative Research, American Sports Medicine Institute, Birmingham, AL. Address correspondence to Dr MichaelM. Reinold, Rehabilitation Coordinator/Assistant Athletic Trainer, Boston Red Sox Baseball Club, Fenway Park, 4 Yawkey Way, Boston, MA 02215. Email: mreinold@redsox.com

    MICHAEL M. REINOLD, PT, DPT, ATC, CSCSH7

  • 106 | february 2009 | volume 39 | number 2 | journal of orthopaedic & sports physical therapy

    [ CLINICAL COMMENTARY ]toid activity (minimizing subacromialimpingement).6,8,9,21,34,50,60,65,74 In addi-tion, rotator cuff muscles are frequentlytreated either conservatively or surgicallysecondary to injuries.

    Exercise designed to strengthen themuscles of the rotator cuff are often pre-scribed to patients with pathologies suchas subacromial impingement. Duringscapular plane abduction in healthy sub-jects, the humeral head translates 1 to 3mm in the superior direction from 0 to30 of abduction, slightly inferiorly from30 to 60 of abduction, and in the su-perior or inferior direction during 60 to90 of abduction.26,50,67 Other data dem-onstrate that, during passive scapularplane abduction, the humeral head trans-lates superiorly 0.6 to 1.8 mm between0 to 150.25,26 But during active scapularplane abduction the humeral head re-mains nearly centered in the glenoid fos-sa throughout the range of movement.26

    These data illustrate the importance ofrotator cuff strength and muscle balanceto resist humeral head superior transla-tion and help center the humeral headwithin the glenoid fossa during shoulderelevation.74 With rotator cuff pathology,altered kinematics and muscle activ-ity are present,31 and superior humeralhead translation increases and subacro-mial space decreases.24 Moreover, duringscapular plane shoulder abduction from30 to 90, infraspinatus and subscapu-laris activity was found to be signicantlyless in individuals with subacromial im-pingement compared to those withoutimpingement.68

    Subjects with shoulder laxity and in-stability have also been shown to havealtered kinematics and ring patterns ofthe rotator cuff.7,35,45,46,55,64,72 Compared tohealthy subjects, patients with general-ized joint laxity demonstrated increasedsubscapularis activity during internalrotation (IR) exercise and decreased su-praspinatus and subscapularis activityduring external rotation (ER) exercise.7,43

    Compared to healthy subjects, those withanterior instability exhibited less su-praspinatus activity between 30 to 60

    of shoulder elevation during abductionand scaption exercises.59

    These EMG data clearly illustrateaberrant muscle-ring patterns in in-dividuals with shoulder pathology. It isoften the goal of rehabilitation special-ists to prescribe exercises to normalize orprevent these abnormal ring patterns.Proper selection of exercises to activatemuscle function for each muscle of therotator cuff should be considered duringrehabilitation.

    IkfhWif_dWjkiThe supraspinatus compresses, abducts,and generates a small ER torque to theglenohumeral joint. Supraspinatus activi-ty increases as resistance increases duringabduction/scaption movements, peakingat 30 to 60 of elevation for any givenresistance. At lower elevation angles, su-praspinatus activity increases, providingadditional humeral head compressionwithin the glenoid fossa to counter thehumeral head superior translation occur-ring with contraction of the deltoid.1 Dueto a decreasing moment arm with abduc-tion, the supraspinatus is a more effectiveabductor in the scapular plane at smallerabduction angles.34,50,65

    Relatively high supraspinatus activityhas been measured in several commonrotator cuff exercises3,5,17,33,54,63,70,75,79,87

    and in several exercises that are notcommonly thought of as rotator cuff ex-ercises, such as standing forward scap-ular punch, rowing exercises, push-upexercises, and 2-hand overhead medi-cine ball throws.13,17,32,81 These resultssuggest the importance of the rotatorcuff in providing dynamic glenohumeralstability by centering the humeral headwithin the glenoid fossa during all up-per extremity functional movements.This is an important concept for theclinician to understand. The musclesability to generate abduction torque inthe scapular plane appears to be great-est with the shoulder in neutral rotationor in slight IR or ER.50,65 This biome-chanical advantage has led to the devel-opment of exercises in the plane of the

    scapula to specically strengthen thesupraspinatus.38

    Jobe38 was the rst to recommend ele-vation in the scapular plane (30 anteriorto the frontal plane) with glenohumer-al IR, or the empty can exercise, tostrengthen the supraspinatus muscle.Other authors37,40,66,69,70,77 have suggestedthe full can position, or elevation in thescapular plane with glenohumeral ER,to best strengthen and test the supraspi-natus muscle. Furthermore, comparedto the empty can exercise, Blackburn5

    reported signicantly greater supraspi-natus activity during prone horizontalabduction at 100 with full ER, or pronefull can, position. The results of studiescomparing these exercises provide in-consistent results due to methodologicallimitations, including lack of statisticalanalysis,38,79 lack of data for all 3 exercis-es,40,54,79,87 and absence of data on deltoidmuscle activity.87

    Recently, Reinold et al69 comprehen-sively evaluated the EMG signal of thesupraspinatus and deltoid musculatureduring the full can, empty can, andprone full can exercises in an attemptto clarify the muscular activation duringthese exercises. The results showed thatall 3 exercises provide a similar amountof supraspinatus activity ranging from62% to 67% of maximal voluntary iso-metric contraction (MVIC). However,the full can exercise demonstrated asignicantly lower amount of middleand posterior deltoid activity comparedto the 2 other exercises. This is clinicallysignicant when trying to strengthenthe supraspinatus while simultaneouslyminimizing potentially disadvanta-geous superior sheer force due to del-toid activity.

    In patients with shoulder pain,weakness of the rotator cuff, or inef-cient dynamic stabilization, it is theauthors opinion that activities thatproduce higher levels of deltoid activ-ity in relation to supraspinatus activity,such as the empty can and prone fullcan exercise, may be detrimental. Thisis due to the increased amount of supe-

  • journal of orthopaedic & sports physical therapy | volume 39 | number 2 | february 2009 | 107

    rior humeral head migration that maybe observed when the rotator cuff doesnot adequately compress the humeruswithin the glenoid fossa to counteract,or oppose, the superior pull of the del-toid (

  • 108 | february 2009 | volume 39 | number 2 | journal of orthopaedic & sports physical therapy

    [ CLINICAL COMMENTARY ]until it is about 1.3 cm at 60 abduction.65

    These data imply that the infraspinatus isa more effective external rotator at lowershoulder abduction angles. The teres mi-nor has a relatively constant ER momentarm (approximately 2.1 cm) and the abil-ity to generate torque throughout shoul-der abduction movement, which impliesthat shoulder abduction angle does notaffect the effectiveness of the teres minorto generate ER torque.65

    Several studies have been designed totest the results of the model; but, as instudies on the supraspinatus, variationsin experimental methodology have result-ed in conicting results and controversyin exercise selection.3,5,17,19,27,33,44,54,63,70,77,79,81

    Several exercises have been recommend-ed based on EMG data, including shoul-der ER in the side-lying,3,70,79 standing,27,70

    or prone3,70 positions performed at 0,3,70

    45,27,70 and 903,70 of abduction. Anotherexercise that has been shown to generatea high EMG signal of the infraspinatusand teres minor is prone horizontal ab-duction with ER.5,79

    Reinold et al70 analyzed several dif-ferent exercises commonly used tostrengthen the shoulder external rota-tors to determine the most effectiveexercise and position to recruit muscleactivity of the posterior rotator cuff. Theauthors report that the exercise that elic-ited the most combined EMG signal forthe infraspinatus and teres minor wasshoulder ER in side-lying (infraspina-tus, 62% maximal voluntary isometriccontraction [MVIC]; teres minor, 67%MVIC), followed closely by standing ERin the scapular plane at 45 of abduction(infraspinatus, 53% MVIC; teres minor,55% MVIC), and nally prone ER in the90 abducted position (infraspinatus,50% MVIC; teres minor, 48% MVIC).

    Exercises in the 90 abducted posi-tion are often incorporated to simulatethe position and strain on the shoulderduring overhead activities such as throw-ing. This position produced moderateactivity of the external rotators but alsoincreased activity of the deltoid and su-praspinatus. It appears that the amount

    of infraspinatus and teres minor activityprogressively decreases as the shouldermoves into an abducted position, whileactivity of the supraspinatus and deltoidincreases. This suggests that as the armmoves into a position of increased vulner-ability away from the body, the supraspi-natus and deltoid are active to assist inthe ER movement, while providing somedegree of glenohumeral stability throughmuscular contraction.

    While standing ER exercises per-formed at 90 of sho

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