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Effects of different movement directions on electromyography recorded from the shoulder muscles while passing the target positions
Journal of Electromyography and Kinesiology 23 (2013) 1362–1369
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Effects of different movement directions on electromyography recorded from the shoulder muscles while passing the target positions Yoshinari Sakaki a,d, Fuminari Kaneko b,⇑, Kota Watanabe c, Takuma Kobayashi c, Masaki Katayose b, Nobuhiro Aoki b, Eriko Shibata a, Toshihiko Yamashita c a
Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan Second Division of Physical Therapy, School of Health Sciences, Sapporo Medical University, Sapporo, Japan Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan d Department of Rehabilitation, Hitsujigaoka Hospital, Sapporo, Japan b c
a r t i c l e
i n f o
Article history: Received 29 January 2013 Received in revised form 7 August 2013 Accepted 28 August 2013
Keywords: Rotator cuff Shoulder joint Electromyography Movement direction Motion analysis
a b s t r a c t Purpose: We compared electromyography (EMG) recorded from the shoulder joint muscles in the same position for different movement directions. Methods: Fifteen healthy subjects participated. They performed shoulder elevation from 0° to 120°, shoulder depression from 120° to 0°, shoulder horizontal adduction from 15° to 105°, and shoulder horizontal abduction from 105° to 15°. The target positions were 90° shoulder elevation in the 0°, 30°, 60°, and 90° planes (0°, 30°, 60°, and 90° positions). EMG signals were recorded from the supraspinatus (SSP) muscle by fine-wire electrodes. EMG signals from the infraspinatus (ISP), anterior deltoid, middle deltoid, and posterior deltoid muscles were recorded using active surface electrodes. Results: During elevation and horizontal abduction, the SSP showed significantly higher activity than that shown during depression and during horizontal adduction in the 0°, 30°, and 60° positions. During elevation, the ISP showed significantly higher activity than during depression and during horizontal adduction in the 90° position. During horizontal abduction, the ISP showed significantly higher activity than during depression in the 90° position. Conclusions: When the movement tasks were performed in different movement directions at the same speed, each muscle showed characteristic activity. Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction Shoulder surface muscles include the deltoid muscle and the pectoralis major muscle, which enable the execution of shoulder movements. The rotator cuff acts to stabilize the glenohumeral joint in various limb positions (Kronberg et al., 1990; Inman et al., 1996; Wuelker et al., 1998). It was reported that in shoulder joint diseases such as subacromial impingement, frozen shoulder and thrower’s pathologic shoulder, the function of the rotator cuff is relatively less than the function of the surface muscles (Williams and Kelley, 2000). Therefore, to understand the mechanisms underlying shoulder joint diseases and to provide the optimal rehabilitation for rotator cuff, a thorough elucidation of the functional characteristics of the rotator cuff is necessary. The functional characteristics of the rotator cuff have been examined in the previous studies using techniques such as a cadaveric shoulder, electromyography, X-rays, and magnetic resonance imaging (Kronberg et al., 1990; Inman et al., 1996; Wuelker
et al., 1998). It was reported that the supraspinatus (SSP) muscle contributes to shoulder abduction movement (Howell et al., 1986; Otis et al., 1994; Alpert et al., 2000), and that the infraspinatus (ISP) muscle pulls the head of the humerus into the glenoid fossa (Alpert et al., 2000; Yanagawa et al., 2008). These studies only focused on the rotator cuff’s functional characteristics in a single movement direction. However, the shoulder’s movements in daily living and sports activities are multidirectional, and the movement direction that passes through the same position in space is generally not one direction. In the previous studies, it was not clarified whether shoulder muscle activity differs during different movement directions when the upper limb is in the same position. The purpose of the present study was to record electromyography from the shoulder joint muscles in the same position for different movement directions. 2. Methods 2.1. Subjects
⇑ Corresponding author. Address: West 17, South 1, Chuo-ku, Sapporo City, Japan. Tel.: +81 11 611 2111. E-mail address: [email protected] (F. Kaneko). 1050-6411/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jelekin.2013.08.010
Fifteen healthy male subjects (aged 23.1 ± 1.2 years) who reported that they did not exercise regularly participated. The study
Y. Sakaki et al. / Journal of Electromyography and Kinesiology 23 (2013) 1362–1369
protocol was approved by the Ethics Committee of Sapporo Medical University. All subjects were right-hand dominant, and dominant shoulders were tested for all subjects. A clinical screening examination of each subject was conducted by a licensed physical therapist and included a test of range-of-motion, Neer test, Hawkin’s test, load and shift test, and sulcus sign (Ludewig et al., 2009). 2.2. Experimental protocol The subject stood on a wooden board with his elbow joint extended and the thumb pointing in the direction of shoulder elevation in the movement planes. The medial borders of the subject’s feet were set on lines drawn on the board, with the distance between the ankles set as 15 cm. The movement tasks were shoulder elevation from 0° to 120°, shoulder depression from 120° to 0°, shoulder horizontal adduction from 15° to 105°, and shoulder horizontal abduction from 105° to 15° (Fig. 1). The subject raised and lowered his shoulder completely across four movement planes. The horizontal abduction angles were 0° (0° plane), 30° (30° plane), 60° (60° plane), and 90° (90° plane). Each subject also completed horizontal adduction and horizontal abduction of the shoulder in the 90° shoulder elevation. The target positions were 90° shoulder elevation in the 0°, 30°, 60°, and 90° planes (0°, 30°, 60°, and 90° positions). The angular velocity was set at 10°/s, and the movement speed was kept constant in accord with the sound of an electronic metronome. The movement time was 12 s. Each movement task was performed third randomly, with an at-least 1 min rest between tasks. First, the subject was instructed to perform a maximal voluntary isometric contraction (MVIC) of the SSP, ISP, anterior deltoid (AD), middle deltoid (MD), and posterior deltoid (PD) muscles. MVIC of the SSP, AD, and MD were recorded in the sitting position,
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and those of the ISP and PD were recorded in the prone position. In MVIC of the SSP, AD, and MD, the subject was instructed to produce the shoulder flexion torque for the AD and to produce the shoulder abduction torque for the SSP and MD. In MVIC of the ISP, the subject was instructed to produce the shoulder external rotation torque. In MVIC of the PD, the subject was instructed to produce the shoulder horizontal abduction torque (Helen and Jacqueline, 2002). The subject was instructed to produce muscular contraction gradually in 2 s, sustained MVIC for 5 s, and then to relax gradually for 2 s. The MVIC was recorded after a total of two MVICs was performed for each movement. Next, after the subject was given time to practice the movement tasks, he performed the movement tasks for recording. Each movement task was performed along vertically placed aluminum poles. A monitor in which a marker was reflected was set in front of the subject. The subjects could check the movement direction and movement speed by looking at the monitor. 3. Instrumentation 3.1. Electromyography Electromyography (EMG) was recorded using surface electrodes and intramuscular fine-wire electrodes by EMG systems (EMG Telemeter System; Harada Electronic Industry Co., Sapporo, Japan). EMG signals were sampled at 1000 Hz and stored on a personal computer. The surface electrodes were placed on the ISP, AD, MD and PD, in accord with related studies (Basmajian and Latif, 1957; Basmajian and Luca, 1985; Kelly et al., 1996; Kaneko et al., 2003; McLean et al., 2003; Kitsunai et al., 2010) (Fig. 2). We used disposable surface electrodes (Blue Sensor P-00-S; Medicotest, Surrey, UK) over the muscle belly, parallel to the muscle fiber orientation with a center-to-center distance of 2 cm. The intramuscular
120° 0° 30° Movement range 60° 4 movement planes
90°
0° Coronal Plane
Horizontal Plane
(a) 120°
-15° 90° Shoulder elevation angle Movement range 105° Horizontal Plane
(b)
0° Coronal Plane
Fig. 1. Shoulder joint movement. (a) the shoulder elevation task and the shoulder depression task. (b) The shoulder horizontal adduction task and the shoulder horizontal abduction task. The shoulder elevation task and shoulder depression task were from 0° to 120°. The shoulder horizontal adduction task and shoulder horizontal abduction task were from 15° to 105°.
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fine-wire electrodes were used for the SSP (Fig. 2). The intramuscular fine-wire electrode placements were based on earlier studies (Delagi and Perotto, 1981; Kaneko et al., 2003). Two fine-wire electrodes (25-lm dia.; Unique Medical Co., Tokyo, Japan) were connected to use as a single bipolar electrode (Kaneko, 2009; Kubota et al., 2009). The site was scrubbed with alcohol prior to applying the fine-wire electrodes. The fine-wire electrodes were inserted into the SSP by an orthopedist. The EMG signals (Fig. 3a) were filtered (Fig. 3b) and full waverectified (Fig. 3c) (LabView 2011; National Instruments Co., Austin, TX, USA). EMG signals were band-pass filtered from 10 to 500 Hz through a 4th-order Butterworth filter (Ebaugh and Spinelli, 2010). The data were low-pass filtered at a cut-off frequency of 3 Hz, and we calculated the averaged rectified value (ARV) (Fig. 3d). The data of each trial were standardized as the average value for 1 s with the MVIC as 100% (%ARV) (Fig. 3e). After determining the %ARV, we calculated the sampling frequency to reduce the samples from 1000 Hz to 50 Hz (Fig. 3f). The muscle activity at each shoulder joint angle was then represented depending on the temporal data of muscle activity (Fig. 3g and h). We performed a three-dimensional spline interpolation of the data and estimated the value at the interpolating point determined depending on the analysis section (Kaneko et al., 2005). The interpolation time interval was 0.1°. Therefore, the number of muscle activity data in 2° of analysis sections in each movement task was standardized to 20 points. 3.2. Motion-capture systems The shoulder joint angle was recorded using an 8-camera motion-capture system (Vicon Nexus; Mechdyne Co., Marshalltown, IA, USA). The angle data were sampled at 50 Hz and stored on a personal computer. The motion-capture markers were attached to the right acromial angle, the right epicondylus lateralis humerus, and the right epicondylus medialis humerus. The segment of the right humerus was defined by these three points in the space coordinate system. The angle data were low-pass filtered at a cut-off frequency of 3 Hz (4th-order Butterworth filter) (Yanagawa et al., 2008). Three-dimensional coordinates were analyzed with a three-dimensional living body model creation tool (Body Builder; Mechdyne Co., Marshalltown, IA, USA). The shoulder joint angle was calculated as the angle of the segment of the right humerus to the space coordinate system. The angle data were differentiated so that the average value of angular velocity, standard deviation (SD), and a coefficient of variation (CV) of angular velocity were obtained from 3.5 s before to after 14.5 s of the trial start.
3.3. Triaxial angular velocity sensor The angular velocity of the shoulder joint movements was recorded using a triaxial angular velocity sensor (9-axis wireless motion sensor; Logical Products, Inc., Waukegan, IL, USA). The angular velocity measured with the angular velocity sensor was used to monitor each trial. The angular velocity was sampled at 200 Hz and stored on a personal computer. The sensor was attached to the distal dorsal part of the subject’s forearm (Wickham et al., 2009). The angular velocity data were filtered, and we calculated the movement time, the average value of angular velocity (AVavg), and the SD and the CV of angular velocity (LabView 2011; National Instruments Co., Austin, TX, USA). All angular velocity data were low-pass filtered at a cut-off frequency of 3 Hz (4th-order Butterworth filter). In elevation and depression, the Z-axis was set as the candidate for analysis, and in horizontal adduction and horizontal abduction, the X-axis was set as the candidate for analysis. The onset time of each movement was made into the point of ±3 or more SD of the average value of the angular velocity which was recorded before the start of each movement, and the end time of each movement was made into the point of ±3 or less SD of the average value of the angular velocity which was recorded before the start of each movement after the time of onset. At this time, the trials in which the movement time exceeded 12.0 ± 2.0 s or more were excluded from the analysis. Moreover, the trials in which the angular velocity deviated ± 10°/s or more were excluded from the analysis. 4. Statistical analysis We used SPSS software (ver 15.0) for the statistical analyses. For the elevation and depression, we calculated the average values and the standard deviation of %ARV at 89–91° shoulder elevation in each plane. For the horizontal adduction and horizontal abduction, we calculated the average value and standard deviation of %ARV at 1° to 1°, 29° to 31°, 59° to 61°, and 89° to 91° shoulder horizontal adduction in the 90° shoulder elevation. We compared the muscle activity in the four movement directions (elevation, depression, horizontal adduction, and horizontal abduction) using one-way analysis of variance (ANOVA) with repeated measures. Post hoc comparisons were made using Bonferroni methods. In addition, we compared the angular velocity, which was calculated with the three-dimensional motion analysis system in the four movement directions (elevation, depression, horizontal adduction, and horizontal abduction) using ANOVA with repeated
SSP
AD PD
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MD
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Fig. 2. Electrode placements. (a) Electrode positions for the AD (anterior deltoid) muscle; (b) the MD (middle deltoid) and PD (posterior deltoid) muscles; (c) and the electrode positions of the supraspinatus (SSP) and infraspinatus (ISP) muscles.
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(a)
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Fig. 3. EMG data of a subject’s anterior deltoid (AD) muscle (elevation in the 90° position). (a) Raw data, (b) filtered data, (c) rectified data, (d) averaged rectified value (ARV), (e) %ARV, (f) %ARV (50 Hz), (g) shoulder joint angle data, and (h) the muscle activity at each shoulder joint angle.
Table 1 The average values of angular velocity (AVavg), SDs, and CVs of angular velocity.
Elevation Depression Horizontal adduction Horizontal abduction Mean
AVavg ± SD (°/s)
CV (%)
10.00 ± 0.91 9.72 ± 0.79 10.44 ± 0.46 10.20 ± 0.52 10.09 ± 0.67
4.62 ± 1.59 4.56 ± 1.43 1.98 ± 1.19 1.49 ± 1.28 3.16 ± 1.37
Elevation
Depression
Horizontal Adduction
Horizontal Abduction
(%ARV) 60
30
(deg/sec) 15
0 Elevation
10
Depression Horizontal Adduction Horizontal Abduction
5 n.s.
0
Average value Fig. 4. The average value of angular velocity during each four direction. The average value of angular velocity did not show a significant difference in the movement direction factor (F = 3.033, p = 0.061).
0° position
30° position
60° position
90° position
Fig. 5. The %ARV values of the SSP (supraspinatus) muscle (n = 15). The SSP showed a significant difference in the movement direction factor in the 0°, 30°, and 60° positions (0° position: F = 7.581, p = 0.006, 30° position: F = 7.674, p = 0.001, 60° position: F = 4.614, p = 0.008). The SSP did not show a significant difference in the movement direction factor in the 90° position (F = 0.538, p = 0.659). : p < 0.05.
of all movement directions. The level of significance was set at p < 0.05. 5. Results 5.1. Angular velocity (Table 1)
measures. Post hoc comparisons were made using Bonferroni methods. Furthermore, in order to understand the relationship between muscle activity and the angular velocity, we used the correlation analysis for EMG activity of each muscle and the angular velocity
The average angular velocity did not show a significant difference with regard to the movement direction (Fig. 4). The average CV value for the angular velocity was less than 5% in each movement task (Elevation: 4.62 ± 1.59, Depression: 4.56 ± 1.43, Horizontal adduction: 1.98 ± 1.19, Horizontal abduction: 1.49 ± 1.28).
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Depression
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(%ARV)
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Depression
Horizontal Adduction
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(%ARV)
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Fig. 6. The %ARV values of the ISP (infraspinatus) muscle (n = 15). The ISP did not show a significant difference in the movement direction factor in the 0°, 30°, and 60° positions (0° position: F = 2.018, p = 0.127, 30° position: F = 0.467, p = 0.707, 60° position: F = 2.811, p = 0.050), but a significant difference in the movement direction factor in the 90° position was observed (F = 7.468, p = 0.001). : p < 0.05.
0° position
Depression
Horizontal Adduction
Horizontal Abduction
60° position
90° position
Fig. 9. The %ARV values of the PD (posterior deltoid) muscle (n = 15). The PD also showed significant differences in the movement direction factor in all positions (0° position: F = 11.551, p < 0.0005, 30° position: F = 11.831, p = 0.001, 60° position: F = 9.568, p < 0.0005, 90° position: F = 9.484, p = 0.001). : p < 0.05.
(deg) Elevation
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Fig. 7. The %ARV values of the AD (anterior deltoid) muscle (n = 15). The AD showed significant differences in the movement direction factor in all positions (0° position: F = 26.077, p < 0.0005, 30° position: F = 34.389, p < 0.0005, 60° position: F = 23.232, p < 0.0005, 90° position: F = 20.784, p < 0.0005). : p < 0.05.
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Fig. 10. Shoulder joint angle data (elevation in the 90° position). (a) Raw data, (b) angular velocity data after differentiation, and (c) EMG raw data of a subject’s anterior deltoid (AD) muscle.
0
0° position
30° position
60° position
90° position
Fig. 8. The %ARV values of the MD (middle deltoid) muscle (n = 15). The MD also showed significant differences in the movement direction factor in all positions (0° position: F = 18.662, p < 0.0005, 30° position: F = 21.009, p < 0.0005, 60° position: F = 10.521, p < 0.0005, 90° position: F = 12.136, p < 0.0005). : p < 0.05.
5.2. Muscle activity 5.2.1. SSP and ISP muscle activity The SSP showed a significant difference in the movement direction factor in the 0°, 30°, and 60° positions (0° position: F = 7.581, p = 0.006, 30° position: F = 7.674, p = 0.001, 60° position:
F = 4.614, p = 0.008). During elevation and horizontal abduction, the SSP showed significantly higher activity than that shown during depression and during horizontal adduction in the 0°, 30°, and 60° positions. The SSP did not show a significant difference in the movement direction factor in the 90° position (Fig. 5). The ISP did not show a significant difference in the movement direction factor in the 0°, 30°, and 60° positions, but we observed a significant difference in the movement direction factor in the 90° position (F = 7.468, p = 0.001). During elevation, the ISP showed significantly higher activity compared to that during depression and that during horizontal adduction in the 90° position. During horizontal abduction, the ISP showed significantly higher activity compared to depression in the 90° position (Fig. 6).
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5.2.2. Deltoid muscles The AD showed significant differences in the movement direction factor in all positions (0° position: F = 26.077, p < 0.0005, 30° position: F = 34.389, p < 0.0005, 60° position: F = 23.232, p < 0.0005, 90° position: F = 20.784, p < 0.0005). During elevation, the AD showed significantly higher activity than during depression, horizontal adduction, and horizontal abduction in all positions. In addition, during horizontal adduction, the AD showed significantly higher activity than depression in the 30° and 90° positions (Fig. 7). The MD also showed significant difference in the movement direction factor in all positions (0° position: F = 18.662, p < 0.0005, 30° position: F = 21.009, p < 0.0005, 60° position: F = 10.521, p < 0.0005, 90° position: F = 12.136, p < 0.0005). During elevation, the MD showed significantly higher activity compared to depression and horizontal adduction in all positions, and during horizontal abduction, the MD showed significantly higher activity than depression in the 0°, 30°, and 90° positions. In addition, during horizontal adduction, the MD showed significantly higher
(%ARV)
activity than depression in the 0° position. During elevation, the MD showed significantly higher activity than horizontal abduction in the 30° and 60° positions (Fig. 8). The PD also showed significant differences in the movement direction factor in all positions (0° position: F = 11.551, p < 0.0005, 30° position: F = 11.831, p = 0.001, 60° position: F = 9.568, p < 0.0005, 90° position: F = 9.484, p = 0.001). During elevation, the PD showed significantly higher activity than depression in all positions, and during horizontal abduction, the PD showed significantly higher activity than depression in the 0°, 30°, and 60° positions. During elevation, the PD showed significantly higher activity than horizontal adduction in the 30°, 60°, and 90° positions. During horizontal abduction, the PD showed significantly higher activity than horizontal adduction in the 60° position (Fig. 9). 5.3. Relationship between each muscle activity and angular velocity Raw data of the SSP muscle activity and angular velocity in the same trial are shown in Fig. 10. In addition, the relationship
(%ARV)
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AD Fig. 11. Relationship between the EMG activity of each muscle and the angular velocities for all movement directions (n = 15). EMG activity for each muscle and the angular velocity did not show a significant correlation (SSP: r = 0.105, p = 0.104, ISP: r = 0.023, p = 0.721, AD: r = 0.023, p = 0.123, MD: r = 0.119, p = 0.066, PD: r = 0.057, p = 0.381).
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between the EMG activity for each muscle and the angular velocities for all movement directions is shown in Fig. 11. The EMG activity for each muscle and the angular velocity did not show a significant correlation.
6. Discussion In previous studies of shoulder kinematics, the subjects received a feedback signal of the motion speed with only a metronome or a signal, and the size of the variation in motion speed was not clear (Inman et al., 1996; Langenderfer et al., 2006). In the present study, the result of the angular velocity sensor was checked immediately after measurement, and when three trials were successful, we decided to finish the test session. As a result, a significant difference in angular velocity among the movement directions was not detected in this study. It was also clear that the CV was less than 5% for each movement task. It was therefore recognized that the angular velocity during the movement tasks was almost constant. The angular velocity of each movement was constant, and the EMG activity of each muscle and angular velocity did not show a correlation. Therefore, the difference in EMG activity can be interpreted as a changing of the movement directions and target positions. In our results, the EMG activity of the SSP changed among movement directions in the 0°, 30°, and 60° positions, while there was no difference in the EMG activity of the SSP among the movement directions in the 90° position. The function of the SSP in elevation has been described as producing shoulder abduction torque in 90° shoulder elevation in the 0° and 30° planes (0° and 30° positions) (Howell et al., 1986; Otis et al., 1994; Alpert et al., 2000). However, the present EMG results indicate that the SSP may have contributed to the execution on shoulder elevation and horizontal abduction movement not only in the 0° and 30° positions but also in the 60° position. Moreover, the SSP’s contribution to movement in the 90° position may be lower than in the 0°, 30°, and 60° positions. However, it becomes a future study because we did not compare the muscle activity among the target positions. In our results, the EMG activity of the ISP changed among movement directions in the 90° position, while there was no difference in the EMG activity of the ISP among the movement directions in the 0°, 30°, and 60° positions. The function of the ISP was described as pulling the head of the humerus into the glenoid fossa in the 0°, 30°, and 90° positions (Yanagawa et al., 2008). However, the present EMG results indicate that the ISP may have contributed to the execution on shoulder elevation and horizontal abduction movement in the 90° position. The present EMG results indicated that the EMG activity of the SSP during elevation was low in the 0°, 30°, 60°, and 90° positions, in that order, whereas the EMG activity of the ISP during elevation was high in the 0°, 30°, 60°, and 90° positions, in that order. The SSP and ISP clearly showed reverse patterns of movement-dependent EMG activity. We consider that these results have clinical implications. In the case of supraspinatus tear, depression may be preferred as a less stressful movement for passing through the target positions in the 0°, 30°, and 60° positions compared to elevation movement tasks. In contrast, there was no difference in the EMG activity of the ISP among the movement directions in the 90° position. On the other hand, in the case of infraspinatus tear, depression may be preferred as a less stressful movement for passing through the target positions in the 90° positions compared to elevation movement tasks. However, there was no difference in the EMG activity of
the ISP among the movement directions in the 0°, 30°, and 60° positions. Our present data may help in the design of therapeutic exercise programs for rotator cuff injuries, since the data make it possible to consider which direction of movement and which movement plane has lower risks when considering therapeutic exercises for these injuries. Our results of the deltoid muscle revealed that the EMG activities of the three fibers of the deltoid muscle during elevation were higher than those during depression in all positions. This result was not contradictory to previous studies. Our findings indicated that the three fibers of the deltoid muscle may act on synergistic muscles. Moreover, the AD during horizontal adduction was higher than those during depression in the 30° and 90° positions. Conversely, the PD during horizontal adduction was lower than those during elevation in the 30°, 60°, and 90° positions. We observed differences in EMG activity between the AD and PD depending on the target position.
7. Conclusions The purpose of this study was to compare electromyography recorded from the shoulder joint muscles in the same position for different movement directions. We found that the SSP was clearly changing depending on the movement direction in the 0°, 30°, and 60° positions, and that it was clearly not dependent on the movement direction in the 90° position. In contrast, although the ISP was clearly changing depending on the movement direction in the 90° position, it was clearly not dependent on the movement direction in the 0°, 30°, and 60° positions. Our results clarified that the SSP and ISP have reverse patterns of movement-dependent EMG activity. This data should be utilized when creating an exercise program in the case of a rotator cuff tear. References Alpert SW, Pink MM, Jobe FW, et al. Electromyographic analysis of deltoid and rotator cuff function under varying loads and speeds. J Shoulder Elbow Surg 2000;9:47–58. Basmajian JV, Latif A. Integrated actions and functions of the chief flexors of the elbow: a detailed electromyographic analysis. J Bone Joint Surg Am 1957;39A:1106–18. Basmajian JV, Luca CJD. Muscles alive: their functions revealed by electromyography. 5th ed. Baltimore: Williams & Wilkins; 1985. Delagi E, Perotto A. Anatomic guide for the electromyography. 2nd ed. Springfield, Charles C Thomas; 1981. Ebaugh DD, Spinelli BA. Scapulothoracic motion and muscle activity during the raising and lowering phases of an overhead reaching task. J Electromyogr Kinesiol 2010;20:199–205. Helen JH, Jacqueline M. Daniels and Worthingham’s muscle testing: techniques of manual examination. 7th ed. Philadelphia: Saunders; 2002. Howell SM, Imobersteg AM, Seger DH, et al. Clarification of the role of the supraspinatus muscle in shoulder function. J Bone Joint Surg Am 1986;68:398–404. Inman VT, Saunders JB, Abbott LC. Observations of the function of the shoulder joint 1944. Clin Orthop Relat Res 1996;330:3–12. Kaneko F. Time-series analysis on the sequential dynamic change in electromyogram recorded from the rotator cuff muscles during throwing. J Joint Surg 2009;28:1353–60. Kaneko F, Masuda T, Kurumatani H, et al. Improved electromyogram recording technique using fine wire electrodes during rapid and ballistic movement. J Jpn Phys Ther Assoc 2003;30:280–7. Kaneko F, Masuda T, Kurumatani H, et al. Analysis on the sequential dynamic change in electromyogram recorded from shoulder muscles during throwing. J Jpn Phys Ther Assoc 2005;32:115–22. Kelly BT, Kadrmas WR, Speer KP. The manual muscle examination for rotator cuff strength. An electromyographic investigation. Am J Sports Med 1996;24:581–8. Kitsunai M, Kaneko F, Aoyama T, et al. A muscle activity characteristics of the scapular muscle during the shoulder abduction-focus on the rhomboid muscle. Biomech 2010;20:217–24.
Y. Sakaki et al. / Journal of Electromyography and Kinesiology 23 (2013) 1362–1369 Kronberg M, Nemeth G, Brostrom LA. Muscle activity and coordination in the normal shoulder. An electromyographic study. Clin Orthop Relat Res 1990;257:76–85. Kubota J, Kaneko F, Shimada M, et al. Effect of joint position on the electromyographic activity of the semitendinosus muscle. J Electromyogr Clin Neurophysiol 2009;49:149–54. Langenderfer JE, Patthanacharoenphon C, Carpenter JE, et al. Variation in external rotation moment arms among subregions of supraspinatus, infraspinatus, and teres minor muscles. J Orthop Res 2006;24:1737–44. Ludewig PM, Phadke V, Braman JP, et al. Motion of the shoulder complex during multiplanar humeral elevation. J Bone Joint Surg Am 2009;91:378–89. McLean L, Chislett M, Keith M, et al. The effect of head position, electrode site, movement and smoothing window in the determination of a reliable maximum voluntary activation of the upper trapezius muscle. J Electromyogr Kinesiol 2003;13:169–80. Otis JC, Jiang CC, Wickiewicz TL, et al. Changes in the moment arms of the rotator cuff and deltoid muscles with abduction and rotation. J Bone Joint Surg Am 1994;76:667–76. Wickham J, Pizzari T, Stansfeld K, et al. Quantifying ‘normal’ shoulder muscle activity during abduction. J Electromyogr Kinesiol 2009;20:212–22. Williams GR, Kelley M. Management of rotator cuff and impingement injuries in the athlete. J Athl Train 2000;35:300–15. Wuelker N, Korell M, Thren K. Dynamic glenohumeral joint stability. J Shoulder Elbow Surg 1998;7:43–52. Yanagawa T, Goodwin CJ, Shelburne KB, et al. Contributions of the individual muscles of the shoulder to glenohumeral joint stability during abduction. J Biomech Eng 2008;130:021024.
Yoshinari Sakaki received the PT from Sapporo Medical University, Japan in 2009, and the MS degree in physical therapy science from Graduate School of Health Sciences, Sapporo Medical University, Japan in 2011. He currently works as the PT at Hitsujigaoka Hospital, Japan. His main interest is electromyographic analysis of function of rotator cuff.
Fuminari Kaneko received his PT from Sapporo Medical University, Japan in 1992, and PhD degree in health science from Graduate School of Medical Sciences, Hiroshima University, Japan in 2001. He worked as visiting research fellow at NeuroMuscular Research Center, Boston University, USA in 2001. Since 2001 he had worked as scientific researcher in National Institute of Advanced industrial Science and Technology, and currently he has been associate professor and chairperson of Sensorimotor Science and Sports Neuroscience Laboratory in Sapporo Medical University, Japan. Since 2010 to 2011, he worked as visiting researcher at Perception et controle du mouvement humain Laboratoire de Neuroscience Integrative et Adaptative, Universite de Provence, France. His main research interest is the neuroscientific study on sensorimotor system and development of rehabilitation intervention based on neuroscience research.
Kota Watanabe received his M.D. from Sapporo Medical University, School of Medicine, Japan in 1993, and PhD degree from Postgraduate School in Sapporo Medical University, Japan in 2009. Since 2000 to 2002, he worked as research fellow at Biomechanics laboratory, Mayo clinic, USA, and currently he has been assistant professor in the Department of Orthopaedic Surgery in Sapporo Medical University School of Medicine, Japan. His research interests include Foot/Ankle Surgery, Knee Surgery, Sports Medicine and Rheumatology
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Takuma Kobayashi received his M.D. from Sapporo Medical University, School of Medicine, Japan in 2004. He currently works as the M.D. in the Department of Orthopaedic Surgery in Sapporo Medical University School of Medicine, Japan. His research interests include Foot/Ankle Surgery, Knee Surgery, and Sports Medicine.
Masaki Katayose is Professor in Sports Physical Therapy in the School of Health Sciences at Sapporo Medical University in Sapporo, Japan and Vice Director in Division of Rehabilitation Medicine at Sapporo Medical University Hospital. His research interests include sports injury prevention and rehabilitation.
Nobuhiro Aoki received the PT from Ibaraki Prefectural University of Health Sciences, Japan in 2004, and the MS degree in physical therapy science from Graduate School of Health Sciences, Ibaraki Prefectural University of Health Sciences, Japan in 2009. He is currently assistant professor of Second Division of Physical Therapy in School of Health Science, Sapporo Medical University, Japan. His main interest is electromyographic analysis of function of hamstrings.
Eriko Shibata received PT from Sapporo Medical University, Japan in 2008, and the MS degree in physical therapy science from Graduate School of Health Sciences, Sapporo Medical University, Japan in 2010. She is currently a PhD-student at the Sensorimotor Science and Sports Neuroscience Laboratory, Sapporo Medical University, Japan. She currently works as the PT at Shinoro Orthopedic Hospital, Japan. Her main interest is kinesthetic perception by tendon vibration.
Toshihiko Yamashita received his M.D. from Sapporo Medical University, School of Medicine, Japan in 1983, and PhD degree from Postgraduate School in Sapporo Medical University, Japan in 1987. Since 1988 to 1990, he worked as Post-doctoral Fellow at Wayne State University, Bioengineering Center, USA, and currently he has been Professor and Chairman in the Department of Orthopaedic Surgery in Sapporo Medical University School of Medicine, Japan and Vice President in Sapporo Medical University Hospital. His research interests include Spine Surgery and Pain Mechanism.
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Journal of Electromyography and Kinesiology journal homepage: www.elsevier.com/locate/jelekin
Effects of different movement directions on electromyography recorded from the shoulder muscles while passing the target positions Yoshinari Sakaki a,d, Fuminari Kaneko b,⇑, Kota Watanabe c, Takuma Kobayashi c, Masaki Katayose b, Nobuhiro Aoki b, Eriko Shibata a, Toshihiko Yamashita c a
Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan Second Division of Physical Therapy, School of Health Sciences, Sapporo Medical University, Sapporo, Japan Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan d Department of Rehabilitation, Hitsujigaoka Hospital, Sapporo, Japan b c
a r t i c l e
i n f o
Article history: Received 29 January 2013 Received in revised form 7 August 2013 Accepted 28 August 2013
Keywords: Rotator cuff Shoulder joint Electromyography Movement direction Motion analysis
a b s t r a c t Purpose: We compared electromyography (EMG) recorded from the shoulder joint muscles in the same position for different movement directions. Methods: Fifteen healthy subjects participated. They performed shoulder elevation from 0° to 120°, shoulder depression from 120° to 0°, shoulder horizontal adduction from 15° to 105°, and shoulder horizontal abduction from 105° to 15°. The target positions were 90° shoulder elevation in the 0°, 30°, 60°, and 90° planes (0°, 30°, 60°, and 90° positions). EMG signals were recorded from the supraspinatus (SSP) muscle by fine-wire electrodes. EMG signals from the infraspinatus (ISP), anterior deltoid, middle deltoid, and posterior deltoid muscles were recorded using active surface electrodes. Results: During elevation and horizontal abduction, the SSP showed significantly higher activity than that shown during depression and during horizontal adduction in the 0°, 30°, and 60° positions. During elevation, the ISP showed significantly higher activity than during depression and during horizontal adduction in the 90° position. During horizontal abduction, the ISP showed significantly higher activity than during depression in the 90° position. Conclusions: When the movement tasks were performed in different movement directions at the same speed, each muscle showed characteristic activity. Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction Shoulder surface muscles include the deltoid muscle and the pectoralis major muscle, which enable the execution of shoulder movements. The rotator cuff acts to stabilize the glenohumeral joint in various limb positions (Kronberg et al., 1990; Inman et al., 1996; Wuelker et al., 1998). It was reported that in shoulder joint diseases such as subacromial impingement, frozen shoulder and thrower’s pathologic shoulder, the function of the rotator cuff is relatively less than the function of the surface muscles (Williams and Kelley, 2000). Therefore, to understand the mechanisms underlying shoulder joint diseases and to provide the optimal rehabilitation for rotator cuff, a thorough elucidation of the functional characteristics of the rotator cuff is necessary. The functional characteristics of the rotator cuff have been examined in the previous studies using techniques such as a cadaveric shoulder, electromyography, X-rays, and magnetic resonance imaging (Kronberg et al., 1990; Inman et al., 1996; Wuelker
et al., 1998). It was reported that the supraspinatus (SSP) muscle contributes to shoulder abduction movement (Howell et al., 1986; Otis et al., 1994; Alpert et al., 2000), and that the infraspinatus (ISP) muscle pulls the head of the humerus into the glenoid fossa (Alpert et al., 2000; Yanagawa et al., 2008). These studies only focused on the rotator cuff’s functional characteristics in a single movement direction. However, the shoulder’s movements in daily living and sports activities are multidirectional, and the movement direction that passes through the same position in space is generally not one direction. In the previous studies, it was not clarified whether shoulder muscle activity differs during different movement directions when the upper limb is in the same position. The purpose of the present study was to record electromyography from the shoulder joint muscles in the same position for different movement directions. 2. Methods 2.1. Subjects
⇑ Corresponding author. Address: West 17, South 1, Chuo-ku, Sapporo City, Japan. Tel.: +81 11 611 2111. E-mail address: [email protected] (F. Kaneko). 1050-6411/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jelekin.2013.08.010
Fifteen healthy male subjects (aged 23.1 ± 1.2 years) who reported that they did not exercise regularly participated. The study
Y. Sakaki et al. / Journal of Electromyography and Kinesiology 23 (2013) 1362–1369
protocol was approved by the Ethics Committee of Sapporo Medical University. All subjects were right-hand dominant, and dominant shoulders were tested for all subjects. A clinical screening examination of each subject was conducted by a licensed physical therapist and included a test of range-of-motion, Neer test, Hawkin’s test, load and shift test, and sulcus sign (Ludewig et al., 2009). 2.2. Experimental protocol The subject stood on a wooden board with his elbow joint extended and the thumb pointing in the direction of shoulder elevation in the movement planes. The medial borders of the subject’s feet were set on lines drawn on the board, with the distance between the ankles set as 15 cm. The movement tasks were shoulder elevation from 0° to 120°, shoulder depression from 120° to 0°, shoulder horizontal adduction from 15° to 105°, and shoulder horizontal abduction from 105° to 15° (Fig. 1). The subject raised and lowered his shoulder completely across four movement planes. The horizontal abduction angles were 0° (0° plane), 30° (30° plane), 60° (60° plane), and 90° (90° plane). Each subject also completed horizontal adduction and horizontal abduction of the shoulder in the 90° shoulder elevation. The target positions were 90° shoulder elevation in the 0°, 30°, 60°, and 90° planes (0°, 30°, 60°, and 90° positions). The angular velocity was set at 10°/s, and the movement speed was kept constant in accord with the sound of an electronic metronome. The movement time was 12 s. Each movement task was performed third randomly, with an at-least 1 min rest between tasks. First, the subject was instructed to perform a maximal voluntary isometric contraction (MVIC) of the SSP, ISP, anterior deltoid (AD), middle deltoid (MD), and posterior deltoid (PD) muscles. MVIC of the SSP, AD, and MD were recorded in the sitting position,
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and those of the ISP and PD were recorded in the prone position. In MVIC of the SSP, AD, and MD, the subject was instructed to produce the shoulder flexion torque for the AD and to produce the shoulder abduction torque for the SSP and MD. In MVIC of the ISP, the subject was instructed to produce the shoulder external rotation torque. In MVIC of the PD, the subject was instructed to produce the shoulder horizontal abduction torque (Helen and Jacqueline, 2002). The subject was instructed to produce muscular contraction gradually in 2 s, sustained MVIC for 5 s, and then to relax gradually for 2 s. The MVIC was recorded after a total of two MVICs was performed for each movement. Next, after the subject was given time to practice the movement tasks, he performed the movement tasks for recording. Each movement task was performed along vertically placed aluminum poles. A monitor in which a marker was reflected was set in front of the subject. The subjects could check the movement direction and movement speed by looking at the monitor. 3. Instrumentation 3.1. Electromyography Electromyography (EMG) was recorded using surface electrodes and intramuscular fine-wire electrodes by EMG systems (EMG Telemeter System; Harada Electronic Industry Co., Sapporo, Japan). EMG signals were sampled at 1000 Hz and stored on a personal computer. The surface electrodes were placed on the ISP, AD, MD and PD, in accord with related studies (Basmajian and Latif, 1957; Basmajian and Luca, 1985; Kelly et al., 1996; Kaneko et al., 2003; McLean et al., 2003; Kitsunai et al., 2010) (Fig. 2). We used disposable surface electrodes (Blue Sensor P-00-S; Medicotest, Surrey, UK) over the muscle belly, parallel to the muscle fiber orientation with a center-to-center distance of 2 cm. The intramuscular
120° 0° 30° Movement range 60° 4 movement planes
90°
0° Coronal Plane
Horizontal Plane
(a) 120°
-15° 90° Shoulder elevation angle Movement range 105° Horizontal Plane
(b)
0° Coronal Plane
Fig. 1. Shoulder joint movement. (a) the shoulder elevation task and the shoulder depression task. (b) The shoulder horizontal adduction task and the shoulder horizontal abduction task. The shoulder elevation task and shoulder depression task were from 0° to 120°. The shoulder horizontal adduction task and shoulder horizontal abduction task were from 15° to 105°.
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fine-wire electrodes were used for the SSP (Fig. 2). The intramuscular fine-wire electrode placements were based on earlier studies (Delagi and Perotto, 1981; Kaneko et al., 2003). Two fine-wire electrodes (25-lm dia.; Unique Medical Co., Tokyo, Japan) were connected to use as a single bipolar electrode (Kaneko, 2009; Kubota et al., 2009). The site was scrubbed with alcohol prior to applying the fine-wire electrodes. The fine-wire electrodes were inserted into the SSP by an orthopedist. The EMG signals (Fig. 3a) were filtered (Fig. 3b) and full waverectified (Fig. 3c) (LabView 2011; National Instruments Co., Austin, TX, USA). EMG signals were band-pass filtered from 10 to 500 Hz through a 4th-order Butterworth filter (Ebaugh and Spinelli, 2010). The data were low-pass filtered at a cut-off frequency of 3 Hz, and we calculated the averaged rectified value (ARV) (Fig. 3d). The data of each trial were standardized as the average value for 1 s with the MVIC as 100% (%ARV) (Fig. 3e). After determining the %ARV, we calculated the sampling frequency to reduce the samples from 1000 Hz to 50 Hz (Fig. 3f). The muscle activity at each shoulder joint angle was then represented depending on the temporal data of muscle activity (Fig. 3g and h). We performed a three-dimensional spline interpolation of the data and estimated the value at the interpolating point determined depending on the analysis section (Kaneko et al., 2005). The interpolation time interval was 0.1°. Therefore, the number of muscle activity data in 2° of analysis sections in each movement task was standardized to 20 points. 3.2. Motion-capture systems The shoulder joint angle was recorded using an 8-camera motion-capture system (Vicon Nexus; Mechdyne Co., Marshalltown, IA, USA). The angle data were sampled at 50 Hz and stored on a personal computer. The motion-capture markers were attached to the right acromial angle, the right epicondylus lateralis humerus, and the right epicondylus medialis humerus. The segment of the right humerus was defined by these three points in the space coordinate system. The angle data were low-pass filtered at a cut-off frequency of 3 Hz (4th-order Butterworth filter) (Yanagawa et al., 2008). Three-dimensional coordinates were analyzed with a three-dimensional living body model creation tool (Body Builder; Mechdyne Co., Marshalltown, IA, USA). The shoulder joint angle was calculated as the angle of the segment of the right humerus to the space coordinate system. The angle data were differentiated so that the average value of angular velocity, standard deviation (SD), and a coefficient of variation (CV) of angular velocity were obtained from 3.5 s before to after 14.5 s of the trial start.
3.3. Triaxial angular velocity sensor The angular velocity of the shoulder joint movements was recorded using a triaxial angular velocity sensor (9-axis wireless motion sensor; Logical Products, Inc., Waukegan, IL, USA). The angular velocity measured with the angular velocity sensor was used to monitor each trial. The angular velocity was sampled at 200 Hz and stored on a personal computer. The sensor was attached to the distal dorsal part of the subject’s forearm (Wickham et al., 2009). The angular velocity data were filtered, and we calculated the movement time, the average value of angular velocity (AVavg), and the SD and the CV of angular velocity (LabView 2011; National Instruments Co., Austin, TX, USA). All angular velocity data were low-pass filtered at a cut-off frequency of 3 Hz (4th-order Butterworth filter). In elevation and depression, the Z-axis was set as the candidate for analysis, and in horizontal adduction and horizontal abduction, the X-axis was set as the candidate for analysis. The onset time of each movement was made into the point of ±3 or more SD of the average value of the angular velocity which was recorded before the start of each movement, and the end time of each movement was made into the point of ±3 or less SD of the average value of the angular velocity which was recorded before the start of each movement after the time of onset. At this time, the trials in which the movement time exceeded 12.0 ± 2.0 s or more were excluded from the analysis. Moreover, the trials in which the angular velocity deviated ± 10°/s or more were excluded from the analysis. 4. Statistical analysis We used SPSS software (ver 15.0) for the statistical analyses. For the elevation and depression, we calculated the average values and the standard deviation of %ARV at 89–91° shoulder elevation in each plane. For the horizontal adduction and horizontal abduction, we calculated the average value and standard deviation of %ARV at 1° to 1°, 29° to 31°, 59° to 61°, and 89° to 91° shoulder horizontal adduction in the 90° shoulder elevation. We compared the muscle activity in the four movement directions (elevation, depression, horizontal adduction, and horizontal abduction) using one-way analysis of variance (ANOVA) with repeated measures. Post hoc comparisons were made using Bonferroni methods. In addition, we compared the angular velocity, which was calculated with the three-dimensional motion analysis system in the four movement directions (elevation, depression, horizontal adduction, and horizontal abduction) using ANOVA with repeated
SSP
AD PD
(a)
MD
(b)
ISP
(c)
Fig. 2. Electrode placements. (a) Electrode positions for the AD (anterior deltoid) muscle; (b) the MD (middle deltoid) and PD (posterior deltoid) muscles; (c) and the electrode positions of the supraspinatus (SSP) and infraspinatus (ISP) muscles.
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(a)
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Fig. 3. EMG data of a subject’s anterior deltoid (AD) muscle (elevation in the 90° position). (a) Raw data, (b) filtered data, (c) rectified data, (d) averaged rectified value (ARV), (e) %ARV, (f) %ARV (50 Hz), (g) shoulder joint angle data, and (h) the muscle activity at each shoulder joint angle.
Table 1 The average values of angular velocity (AVavg), SDs, and CVs of angular velocity.
Elevation Depression Horizontal adduction Horizontal abduction Mean
AVavg ± SD (°/s)
CV (%)
10.00 ± 0.91 9.72 ± 0.79 10.44 ± 0.46 10.20 ± 0.52 10.09 ± 0.67
4.62 ± 1.59 4.56 ± 1.43 1.98 ± 1.19 1.49 ± 1.28 3.16 ± 1.37
Elevation
Depression
Horizontal Adduction
Horizontal Abduction
(%ARV) 60
30
(deg/sec) 15
0 Elevation
10
Depression Horizontal Adduction Horizontal Abduction
5 n.s.
0
Average value Fig. 4. The average value of angular velocity during each four direction. The average value of angular velocity did not show a significant difference in the movement direction factor (F = 3.033, p = 0.061).
0° position
30° position
60° position
90° position
Fig. 5. The %ARV values of the SSP (supraspinatus) muscle (n = 15). The SSP showed a significant difference in the movement direction factor in the 0°, 30°, and 60° positions (0° position: F = 7.581, p = 0.006, 30° position: F = 7.674, p = 0.001, 60° position: F = 4.614, p = 0.008). The SSP did not show a significant difference in the movement direction factor in the 90° position (F = 0.538, p = 0.659). : p < 0.05.
of all movement directions. The level of significance was set at p < 0.05. 5. Results 5.1. Angular velocity (Table 1)
measures. Post hoc comparisons were made using Bonferroni methods. Furthermore, in order to understand the relationship between muscle activity and the angular velocity, we used the correlation analysis for EMG activity of each muscle and the angular velocity
The average angular velocity did not show a significant difference with regard to the movement direction (Fig. 4). The average CV value for the angular velocity was less than 5% in each movement task (Elevation: 4.62 ± 1.59, Depression: 4.56 ± 1.43, Horizontal adduction: 1.98 ± 1.19, Horizontal abduction: 1.49 ± 1.28).
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Y. Sakaki et al. / Journal of Electromyography and Kinesiology 23 (2013) 1362–1369 Elevation
Depression
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(%ARV)
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Depression
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(%ARV)
30
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Fig. 6. The %ARV values of the ISP (infraspinatus) muscle (n = 15). The ISP did not show a significant difference in the movement direction factor in the 0°, 30°, and 60° positions (0° position: F = 2.018, p = 0.127, 30° position: F = 0.467, p = 0.707, 60° position: F = 2.811, p = 0.050), but a significant difference in the movement direction factor in the 90° position was observed (F = 7.468, p = 0.001). : p < 0.05.
0° position
Depression
Horizontal Adduction
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Fig. 9. The %ARV values of the PD (posterior deltoid) muscle (n = 15). The PD also showed significant differences in the movement direction factor in all positions (0° position: F = 11.551, p < 0.0005, 30° position: F = 11.831, p = 0.001, 60° position: F = 9.568, p < 0.0005, 90° position: F = 9.484, p = 0.001). : p < 0.05.
(deg) Elevation
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Fig. 7. The %ARV values of the AD (anterior deltoid) muscle (n = 15). The AD showed significant differences in the movement direction factor in all positions (0° position: F = 26.077, p < 0.0005, 30° position: F = 34.389, p < 0.0005, 60° position: F = 23.232, p < 0.0005, 90° position: F = 20.784, p < 0.0005). : p < 0.05.
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Fig. 10. Shoulder joint angle data (elevation in the 90° position). (a) Raw data, (b) angular velocity data after differentiation, and (c) EMG raw data of a subject’s anterior deltoid (AD) muscle.
0
0° position
30° position
60° position
90° position
Fig. 8. The %ARV values of the MD (middle deltoid) muscle (n = 15). The MD also showed significant differences in the movement direction factor in all positions (0° position: F = 18.662, p < 0.0005, 30° position: F = 21.009, p < 0.0005, 60° position: F = 10.521, p < 0.0005, 90° position: F = 12.136, p < 0.0005). : p < 0.05.
5.2. Muscle activity 5.2.1. SSP and ISP muscle activity The SSP showed a significant difference in the movement direction factor in the 0°, 30°, and 60° positions (0° position: F = 7.581, p = 0.006, 30° position: F = 7.674, p = 0.001, 60° position:
F = 4.614, p = 0.008). During elevation and horizontal abduction, the SSP showed significantly higher activity than that shown during depression and during horizontal adduction in the 0°, 30°, and 60° positions. The SSP did not show a significant difference in the movement direction factor in the 90° position (Fig. 5). The ISP did not show a significant difference in the movement direction factor in the 0°, 30°, and 60° positions, but we observed a significant difference in the movement direction factor in the 90° position (F = 7.468, p = 0.001). During elevation, the ISP showed significantly higher activity compared to that during depression and that during horizontal adduction in the 90° position. During horizontal abduction, the ISP showed significantly higher activity compared to depression in the 90° position (Fig. 6).
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5.2.2. Deltoid muscles The AD showed significant differences in the movement direction factor in all positions (0° position: F = 26.077, p < 0.0005, 30° position: F = 34.389, p < 0.0005, 60° position: F = 23.232, p < 0.0005, 90° position: F = 20.784, p < 0.0005). During elevation, the AD showed significantly higher activity than during depression, horizontal adduction, and horizontal abduction in all positions. In addition, during horizontal adduction, the AD showed significantly higher activity than depression in the 30° and 90° positions (Fig. 7). The MD also showed significant difference in the movement direction factor in all positions (0° position: F = 18.662, p < 0.0005, 30° position: F = 21.009, p < 0.0005, 60° position: F = 10.521, p < 0.0005, 90° position: F = 12.136, p < 0.0005). During elevation, the MD showed significantly higher activity compared to depression and horizontal adduction in all positions, and during horizontal abduction, the MD showed significantly higher activity than depression in the 0°, 30°, and 90° positions. In addition, during horizontal adduction, the MD showed significantly higher
(%ARV)
activity than depression in the 0° position. During elevation, the MD showed significantly higher activity than horizontal abduction in the 30° and 60° positions (Fig. 8). The PD also showed significant differences in the movement direction factor in all positions (0° position: F = 11.551, p < 0.0005, 30° position: F = 11.831, p = 0.001, 60° position: F = 9.568, p < 0.0005, 90° position: F = 9.484, p = 0.001). During elevation, the PD showed significantly higher activity than depression in all positions, and during horizontal abduction, the PD showed significantly higher activity than depression in the 0°, 30°, and 60° positions. During elevation, the PD showed significantly higher activity than horizontal adduction in the 30°, 60°, and 90° positions. During horizontal abduction, the PD showed significantly higher activity than horizontal adduction in the 60° position (Fig. 9). 5.3. Relationship between each muscle activity and angular velocity Raw data of the SSP muscle activity and angular velocity in the same trial are shown in Fig. 10. In addition, the relationship
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AD Fig. 11. Relationship between the EMG activity of each muscle and the angular velocities for all movement directions (n = 15). EMG activity for each muscle and the angular velocity did not show a significant correlation (SSP: r = 0.105, p = 0.104, ISP: r = 0.023, p = 0.721, AD: r = 0.023, p = 0.123, MD: r = 0.119, p = 0.066, PD: r = 0.057, p = 0.381).
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between the EMG activity for each muscle and the angular velocities for all movement directions is shown in Fig. 11. The EMG activity for each muscle and the angular velocity did not show a significant correlation.
6. Discussion In previous studies of shoulder kinematics, the subjects received a feedback signal of the motion speed with only a metronome or a signal, and the size of the variation in motion speed was not clear (Inman et al., 1996; Langenderfer et al., 2006). In the present study, the result of the angular velocity sensor was checked immediately after measurement, and when three trials were successful, we decided to finish the test session. As a result, a significant difference in angular velocity among the movement directions was not detected in this study. It was also clear that the CV was less than 5% for each movement task. It was therefore recognized that the angular velocity during the movement tasks was almost constant. The angular velocity of each movement was constant, and the EMG activity of each muscle and angular velocity did not show a correlation. Therefore, the difference in EMG activity can be interpreted as a changing of the movement directions and target positions. In our results, the EMG activity of the SSP changed among movement directions in the 0°, 30°, and 60° positions, while there was no difference in the EMG activity of the SSP among the movement directions in the 90° position. The function of the SSP in elevation has been described as producing shoulder abduction torque in 90° shoulder elevation in the 0° and 30° planes (0° and 30° positions) (Howell et al., 1986; Otis et al., 1994; Alpert et al., 2000). However, the present EMG results indicate that the SSP may have contributed to the execution on shoulder elevation and horizontal abduction movement not only in the 0° and 30° positions but also in the 60° position. Moreover, the SSP’s contribution to movement in the 90° position may be lower than in the 0°, 30°, and 60° positions. However, it becomes a future study because we did not compare the muscle activity among the target positions. In our results, the EMG activity of the ISP changed among movement directions in the 90° position, while there was no difference in the EMG activity of the ISP among the movement directions in the 0°, 30°, and 60° positions. The function of the ISP was described as pulling the head of the humerus into the glenoid fossa in the 0°, 30°, and 90° positions (Yanagawa et al., 2008). However, the present EMG results indicate that the ISP may have contributed to the execution on shoulder elevation and horizontal abduction movement in the 90° position. The present EMG results indicated that the EMG activity of the SSP during elevation was low in the 0°, 30°, 60°, and 90° positions, in that order, whereas the EMG activity of the ISP during elevation was high in the 0°, 30°, 60°, and 90° positions, in that order. The SSP and ISP clearly showed reverse patterns of movement-dependent EMG activity. We consider that these results have clinical implications. In the case of supraspinatus tear, depression may be preferred as a less stressful movement for passing through the target positions in the 0°, 30°, and 60° positions compared to elevation movement tasks. In contrast, there was no difference in the EMG activity of the ISP among the movement directions in the 90° position. On the other hand, in the case of infraspinatus tear, depression may be preferred as a less stressful movement for passing through the target positions in the 90° positions compared to elevation movement tasks. However, there was no difference in the EMG activity of
the ISP among the movement directions in the 0°, 30°, and 60° positions. Our present data may help in the design of therapeutic exercise programs for rotator cuff injuries, since the data make it possible to consider which direction of movement and which movement plane has lower risks when considering therapeutic exercises for these injuries. Our results of the deltoid muscle revealed that the EMG activities of the three fibers of the deltoid muscle during elevation were higher than those during depression in all positions. This result was not contradictory to previous studies. Our findings indicated that the three fibers of the deltoid muscle may act on synergistic muscles. Moreover, the AD during horizontal adduction was higher than those during depression in the 30° and 90° positions. Conversely, the PD during horizontal adduction was lower than those during elevation in the 30°, 60°, and 90° positions. We observed differences in EMG activity between the AD and PD depending on the target position.
7. Conclusions The purpose of this study was to compare electromyography recorded from the shoulder joint muscles in the same position for different movement directions. We found that the SSP was clearly changing depending on the movement direction in the 0°, 30°, and 60° positions, and that it was clearly not dependent on the movement direction in the 90° position. In contrast, although the ISP was clearly changing depending on the movement direction in the 90° position, it was clearly not dependent on the movement direction in the 0°, 30°, and 60° positions. Our results clarified that the SSP and ISP have reverse patterns of movement-dependent EMG activity. This data should be utilized when creating an exercise program in the case of a rotator cuff tear. References Alpert SW, Pink MM, Jobe FW, et al. Electromyographic analysis of deltoid and rotator cuff function under varying loads and speeds. J Shoulder Elbow Surg 2000;9:47–58. Basmajian JV, Latif A. Integrated actions and functions of the chief flexors of the elbow: a detailed electromyographic analysis. J Bone Joint Surg Am 1957;39A:1106–18. Basmajian JV, Luca CJD. Muscles alive: their functions revealed by electromyography. 5th ed. Baltimore: Williams & Wilkins; 1985. Delagi E, Perotto A. Anatomic guide for the electromyography. 2nd ed. Springfield, Charles C Thomas; 1981. Ebaugh DD, Spinelli BA. Scapulothoracic motion and muscle activity during the raising and lowering phases of an overhead reaching task. J Electromyogr Kinesiol 2010;20:199–205. Helen JH, Jacqueline M. Daniels and Worthingham’s muscle testing: techniques of manual examination. 7th ed. Philadelphia: Saunders; 2002. Howell SM, Imobersteg AM, Seger DH, et al. Clarification of the role of the supraspinatus muscle in shoulder function. J Bone Joint Surg Am 1986;68:398–404. Inman VT, Saunders JB, Abbott LC. Observations of the function of the shoulder joint 1944. Clin Orthop Relat Res 1996;330:3–12. Kaneko F. Time-series analysis on the sequential dynamic change in electromyogram recorded from the rotator cuff muscles during throwing. J Joint Surg 2009;28:1353–60. Kaneko F, Masuda T, Kurumatani H, et al. Improved electromyogram recording technique using fine wire electrodes during rapid and ballistic movement. J Jpn Phys Ther Assoc 2003;30:280–7. Kaneko F, Masuda T, Kurumatani H, et al. Analysis on the sequential dynamic change in electromyogram recorded from shoulder muscles during throwing. J Jpn Phys Ther Assoc 2005;32:115–22. Kelly BT, Kadrmas WR, Speer KP. The manual muscle examination for rotator cuff strength. An electromyographic investigation. Am J Sports Med 1996;24:581–8. Kitsunai M, Kaneko F, Aoyama T, et al. A muscle activity characteristics of the scapular muscle during the shoulder abduction-focus on the rhomboid muscle. Biomech 2010;20:217–24.
Y. Sakaki et al. / Journal of Electromyography and Kinesiology 23 (2013) 1362–1369 Kronberg M, Nemeth G, Brostrom LA. Muscle activity and coordination in the normal shoulder. An electromyographic study. Clin Orthop Relat Res 1990;257:76–85. Kubota J, Kaneko F, Shimada M, et al. Effect of joint position on the electromyographic activity of the semitendinosus muscle. J Electromyogr Clin Neurophysiol 2009;49:149–54. Langenderfer JE, Patthanacharoenphon C, Carpenter JE, et al. Variation in external rotation moment arms among subregions of supraspinatus, infraspinatus, and teres minor muscles. J Orthop Res 2006;24:1737–44. Ludewig PM, Phadke V, Braman JP, et al. Motion of the shoulder complex during multiplanar humeral elevation. J Bone Joint Surg Am 2009;91:378–89. McLean L, Chislett M, Keith M, et al. The effect of head position, electrode site, movement and smoothing window in the determination of a reliable maximum voluntary activation of the upper trapezius muscle. J Electromyogr Kinesiol 2003;13:169–80. Otis JC, Jiang CC, Wickiewicz TL, et al. Changes in the moment arms of the rotator cuff and deltoid muscles with abduction and rotation. J Bone Joint Surg Am 1994;76:667–76. Wickham J, Pizzari T, Stansfeld K, et al. Quantifying ‘normal’ shoulder muscle activity during abduction. J Electromyogr Kinesiol 2009;20:212–22. Williams GR, Kelley M. Management of rotator cuff and impingement injuries in the athlete. J Athl Train 2000;35:300–15. Wuelker N, Korell M, Thren K. Dynamic glenohumeral joint stability. J Shoulder Elbow Surg 1998;7:43–52. Yanagawa T, Goodwin CJ, Shelburne KB, et al. Contributions of the individual muscles of the shoulder to glenohumeral joint stability during abduction. J Biomech Eng 2008;130:021024.
Yoshinari Sakaki received the PT from Sapporo Medical University, Japan in 2009, and the MS degree in physical therapy science from Graduate School of Health Sciences, Sapporo Medical University, Japan in 2011. He currently works as the PT at Hitsujigaoka Hospital, Japan. His main interest is electromyographic analysis of function of rotator cuff.
Fuminari Kaneko received his PT from Sapporo Medical University, Japan in 1992, and PhD degree in health science from Graduate School of Medical Sciences, Hiroshima University, Japan in 2001. He worked as visiting research fellow at NeuroMuscular Research Center, Boston University, USA in 2001. Since 2001 he had worked as scientific researcher in National Institute of Advanced industrial Science and Technology, and currently he has been associate professor and chairperson of Sensorimotor Science and Sports Neuroscience Laboratory in Sapporo Medical University, Japan. Since 2010 to 2011, he worked as visiting researcher at Perception et controle du mouvement humain Laboratoire de Neuroscience Integrative et Adaptative, Universite de Provence, France. His main research interest is the neuroscientific study on sensorimotor system and development of rehabilitation intervention based on neuroscience research.
Kota Watanabe received his M.D. from Sapporo Medical University, School of Medicine, Japan in 1993, and PhD degree from Postgraduate School in Sapporo Medical University, Japan in 2009. Since 2000 to 2002, he worked as research fellow at Biomechanics laboratory, Mayo clinic, USA, and currently he has been assistant professor in the Department of Orthopaedic Surgery in Sapporo Medical University School of Medicine, Japan. His research interests include Foot/Ankle Surgery, Knee Surgery, Sports Medicine and Rheumatology
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Takuma Kobayashi received his M.D. from Sapporo Medical University, School of Medicine, Japan in 2004. He currently works as the M.D. in the Department of Orthopaedic Surgery in Sapporo Medical University School of Medicine, Japan. His research interests include Foot/Ankle Surgery, Knee Surgery, and Sports Medicine.
Masaki Katayose is Professor in Sports Physical Therapy in the School of Health Sciences at Sapporo Medical University in Sapporo, Japan and Vice Director in Division of Rehabilitation Medicine at Sapporo Medical University Hospital. His research interests include sports injury prevention and rehabilitation.
Nobuhiro Aoki received the PT from Ibaraki Prefectural University of Health Sciences, Japan in 2004, and the MS degree in physical therapy science from Graduate School of Health Sciences, Ibaraki Prefectural University of Health Sciences, Japan in 2009. He is currently assistant professor of Second Division of Physical Therapy in School of Health Science, Sapporo Medical University, Japan. His main interest is electromyographic analysis of function of hamstrings.
Eriko Shibata received PT from Sapporo Medical University, Japan in 2008, and the MS degree in physical therapy science from Graduate School of Health Sciences, Sapporo Medical University, Japan in 2010. She is currently a PhD-student at the Sensorimotor Science and Sports Neuroscience Laboratory, Sapporo Medical University, Japan. She currently works as the PT at Shinoro Orthopedic Hospital, Japan. Her main interest is kinesthetic perception by tendon vibration.
Toshihiko Yamashita received his M.D. from Sapporo Medical University, School of Medicine, Japan in 1983, and PhD degree from Postgraduate School in Sapporo Medical University, Japan in 1987. Since 1988 to 1990, he worked as Post-doctoral Fellow at Wayne State University, Bioengineering Center, USA, and currently he has been Professor and Chairman in the Department of Orthopaedic Surgery in Sapporo Medical University School of Medicine, Japan and Vice President in Sapporo Medical University Hospital. His research interests include Spine Surgery and Pain Mechanism.