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The Most Effective Exercise for Strengthening the ...

The most Effective Exercise forStrengthening the Supraspinatus MuscleEvaluation by Magnetic Resonance Imaging*Yoshitsugu Takeda, MD, PhD, Shinji Kashiwaguchi, MD, PhD, Kenji Endo, MD,Tetsuya Matsuura, MD, and Takahiro Sasa, MDFrom the Department of Orthopaedic Surgery, Tokushima Red Cross Hospital, and the Department of Orthopedic Surgery, The University of Tokushima School of Medicine,Tokushima, JapanABSTRACTB ackground:Electromyography has been used to de-termine the best Exercise for Strengthening the supraspi-natus muscle, but conflicting results have been resonance imaging T2 relaxation time appearsto be more accurate in determining muscle :To determine the best exercises for strength-ening the supraspinatus design:Criterion :Six male volunteers performed three exer-cises: the empty can, the full can, and horizontal abduc-tion.

The purpose of the present study was to determine the most effective exercise for the supraspinatus muscle by using MRI to measure T2 relaxation time for the rotator

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1 The most Effective Exercise forStrengthening the Supraspinatus MuscleEvaluation by Magnetic Resonance Imaging*Yoshitsugu Takeda, MD, PhD, Shinji Kashiwaguchi, MD, PhD, Kenji Endo, MD,Tetsuya Matsuura, MD, and Takahiro Sasa, MDFrom the Department of Orthopaedic Surgery, Tokushima Red Cross Hospital, and the Department of Orthopedic Surgery, The University of Tokushima School of Medicine,Tokushima, JapanABSTRACTB ackground:Electromyography has been used to de-termine the best Exercise for Strengthening the supraspi-natus muscle, but conflicting results have been resonance imaging T2 relaxation time appearsto be more accurate in determining muscle :To determine the best exercises for strength-ening the supraspinatus design:Criterion :Six male volunteers performed three exer-cises: the empty can, the full can, and horizontal abduc-tion.

2 Immediately before and after each Exercise , mag-netic resonance imaging examinations were performedand changes in relaxation time for the subscapularis,supraspinatus, infraspinatus, teres minor, and deltoidmuscles were :The supraspinatus muscle had the greatestchange among the studied muscles in relaxation time forthe empty can ( ms) and full can ( ms) the horizontal abduction Exercise the change inrelaxation time for the supraspinatus muscle ( ms)was significantly smaller than that for the posterior deltoidmuscle ( ms) and not significantly different from thatof the other muscles :The empty can and full can exercises weremost Effective in activating the supraspinatus of the rotator cuff muscles, especially thesupraspinatus muscle, is one of the most integral parts ofa rehabilitation program for athletes with shoulder prob-lems who are involved in overhead throwing sports.

3 Jobeand Moynes19suggested that abduction in the scapularplane with internal rotation, the so-called empty can ex-ercise, is the optimal position for isolating the supraspi-natus muscle for Strengthening and manual muscle test-ing. However, Blackburn et that the proneposition with the elbow extended and the shoulder ab-ducted to 100 and externally rotated produced the great-est amount of EMG activity in the supraspinatus et that there was no significant differ-ence in supraspinatus muscle EMG activation betweenabduction in the scapular plane with internal rotation andabduction in the scapular plane with external divergent results can be attributed to several fac-tors, such as characteristics of the subjects, testing proce-dure used, and EMG analysis.

4 Although a higher level ofEMG reproducibility was reported by Kelly et al.,24short-falls with the use of EMG still exist. The intramusculardual fine wire electrodes used in EMG detect the activityof only a small number of muscle fibers and sometimesmigrate during Exercise . This may help explain the rela-tively poor reproducibility of EMG15, 25, 29and may be an-other possible reason for the divergent in muscle proton spin-spin relaxation time (T2)have been shown to correlate positively with activation in-tensity for concentric and eccentric muscle , 10, 13, 34 Furthermore, the relationship between pro-ton T2 relaxation time and contraction amplitude is findings indicate that MRI can be used to study skel-etal muscle function, with T2 relaxation time serving as aquantitative index of activation.

5 Researchers in several stud-ies have tabulated changes in muscle T2 relaxation times tomonitor the pattern of muscle recruitment during variousexercises in human , 9, 10, 12, 16, 32, 34, 38*Presented at the 5th Korea-Japan Joint Meeting of Orthopedic SportsMedicine, Kyongju, Korea, June 2000, and at the 47th annual meeting of TheOrthopaedic Research Society, San Francisco, California, February 2001. Address correspondence and reprint requests to Yoshitsugu Takeda, MD,PhD, Department of Orthopaedic Surgery, Tokushima Red Cross Hospital,28 1 Shinbiraki, Chuden-cho, Komatsushima City, Tokushima,773 author or related institution has received any financial benefit fromresearch in this $ OFSPORTSMEDICINE, Vol.

6 30, No. 3 2002 American Orthopaedic Society for Sports Medicine374 The purpose of the present study was to determine themost Effective Exercise for the supraspinatus muscle byusing MRI to measure T2 relaxation time for the rotatorcuff and deltoid muscles before and after three types AND METHODSS ubjectsSix male subjects without shoulder problems volunteeredto participate. Their average age was years (range, 25to 29), average height was cm (range, 161 to 180),and average weight was kg (range, 62 to 72). Allsubjects were familiar with the three types of exercisesstudied and all were given instructions before starting ProtocolThree types of Exercise were performed: 1) the empty canexercise, in which subjects abducted their arm to 90 inthe scapular plane with internal rotation19(Fig.

7 1A), 2)the full can Exercise , in which subjects abducted their armto 90 in the scapular plane with external rotation17, 24(Fig. 1B), and 3) the horizontal abduction Exercise , inwhich subjects started in a prone position with 90 ofshoulder flexion and horizontally abducted their arm withexternal rotation until their arm was parallel to the the end point of this last Exercise , the arm is in 100 ofabduction to the trunk5(Fig. 1C). A wrist weight of 20repetitive maximum was used for each representing a 20 repetitive maximum (that is, theweight at which the subject can perform only 20 repeti-tions) was determined for each subject at least 1 weekbefore MRI examination.

8 Three sets of each Exercise , sep-arated by 2 minutes of rest, were performed, with each setconsisting of 15 repetitions. Exercises were performed atthe MR imaging facility so that imaging could be per-formed before and immediately after Exercise . The threetypes of Exercise with MRI examinations were performedat 1-week intervals, and the order of Exercise types TechniqueMagnetic resonance imaging of the subjects shoulderswas performed before and immediately after the sagittal MR images were acquired with a scanner (Shimadzu, Kyoto, Japan) with a dedicatedshoulder extremity coil supplied by the same manufac-turer.

9 Subjects were placed in a supine position, and thehumerus was positioned in internal rotation. Two T2-weighted images were collected (repetition time, 2000 ms;echo time, 20 and 90 ms). A 256 256 matrix was ac-quired with one excitation and a 20-cm field of view. Totalcollecting time was 3 minutes, 20 seconds. Twelve 4-mmslices were collected at 1-mm intervals. An ink mark wasmade at the lateral margin of the acromion to ensure asimilar shoulder joint position in the magnet bore betweenrepeated images. Images for calculation were created fromthese two T2-weighted AnalysisRelaxation time values before and after Exercise weremeasured in a region of interest (region of interest; 42 Figure three exercises used: A, empty can Exercise ;B, full can Exercise ; C, horizontal abduction 30, No.)

10 3, 2002 Supraspinatus Muscle Strengthening375mm2) within the muscles. Each region of interest wasselected to avoid any visible blood vessels or fat. Two tothree regions of interest were selected for each times were measured for the subscapularis,supraspinatus, infraspinatus, and teres minor musclesand the anterior, middle, and posterior portions of thedeltoid muscle before and after each Exercise . Relaxationtime was measured on the same image for all musclesexcept the anterior and middle portions of the deltoidmuscle. Calculations were performed using software pro-vided with the Shimadzu system.


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