Selective Activation of the Latissimus Dorsi and the Inferior Fibers of Trapezius at Various Shoulder Angles During Isometric Pu

Journal of Electromyography and Kinesiology 23 (2013) 1350–1355

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Journal of Electromyography and Kinesiology

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Selective activation of the latissimus dorsi and the inferior ﬁbers of trapezius at various shoulder angles during isometric pull-down exertion ⇑ Se-yeon Park a, Won-gyu Yoo b, a Department of Physical Therapy, The Graduate School, Inje University, Republic of Korea b Department of Physical Therapy, College of Biomedical Science and Engineering, Inje University, 607 Obangdong, Gimhae, Gyeongsangnam-do 621-749, Republic of Korea article info abstract

Article history: The aim of this study was to determine the effect of isometric pull down exercise on muscle activity with Received 25 April 2013 shoulder elevation angles of 60°,90°, and 120° and sagittal, scapular, and frontal movement planes, by Received in revised form 19 July 2013 electromyography (EMG) of the latissimus dorsi, inferior fibers of trapezius, and latissimus dorsi/inferior Accepted 20 August 2013 fibers of trapezius activity ratio. Fourteen men performed nine conditions of isometric pull down exercise (three conditions of shoulder elevation Â three conditions of movement planes). Surface EMG was used to collect data from the latissimus dorsi and inferior fibers of trapezius during exercise. Two-way Keywords: repeated analysis of variance with two within-subject factors (shoulder elevation angles and planes of Arm elevation Electromyography movement) was used to determine the significance of the latissimus dorsi and inferior fibers of trapezius Isometric exercise activity and latissimus dorsi/inferior fibers of trapezius activity ratio. The latissimus dorsi activity and LPD ratio between the latissimus dorsi and the inferior fibers of trapezius were significantly decreased as shoulder elevation angle increased from 60° to 120°. The inferior fibers of trapezius activity was significantly increased with shoulder elevation angle. The EMG activity and the ratios were not affected by changes in movement planes. This study suggests that selective activation of the latissimus dorsi is accomplished with a low shoulder elevation angle, while the inferior fibers of the trapezius are activated with high shoulder elevation angles. Ó 2013 Elsevier Ltd. All rights reserved.

1. Introduction et al. (1995) have investigated muscle power after reconstructive surgery, and have concluded that power deficit in the shoulder Selecting a proper strengthening exercise is essential for patients extension and adduction remains. with shoulder injury and dysfunction to regain their muscle perfor- In the rehabilitation setting, some recent findings implied the mance and functional movement (Holmgren et al., 2012; Marinko increasing importance of surgery, such as the capsular shift for pa- et al., 2011). Clinical literature have emphasized the exercise for tients with shoulder instability, to restore normative kinematics. activating rotator cuff or scapulothoracic musculature, whose mus- However, the findings also demonstrated that proper postopera- cle components contribute to functional arm elevation (Holmgren tive rehabilitation treatment is necessary to regain control of the et al., 2012; Neumann, 2002). However, some surgery is needed to scapulothoracic and glenohumeral musculature (Kiss et al., 2010; rehabilitate other muscles such as the latissimus dorsi. The latissi- Illyés and Kiss, 2007). Compared with controls, patients with mus dorsi is a broad muscle with many vascular branches and inner- shoulder instability showed greater displacement between the vations; therefore, it has been used as a donor site for reconstructive rotation center of the scapula and humerus as well as increased surgery (Spear and Hess, 2005). According to previous studies, loss glenohumeral motion and decreased scapulothoracic motion dur- of the latissimus dorsi could result in functional impairment after ing arm elevation (Illyés and Kiss, 2006). For patients with shoul- this kind of surgery (Forthomme et al., 2010; Koh and Morrison, der instability, strengthening the inferior fibers of the trapezius 2009; Fraulin et al., 1995). Forthomme et al. (2010) have reported might be more adequate than strengthening the inferior fibers of muscle weakness after latissimus dorsi transfer; mainly in the the latissimus dorsi. This is because activation of the inferior fibers shoulder adductor and internal rotator muscles. In addition, Fraulin of the trapezius is directly associated with the scapulothoracic joint, especially the upward rotation of the scapula during arm elevation. ⇑ Corresponding author. Tel.: +82 55 320 3994; fax: +82 55 329 1678. E-mail address: [email protected] (W.-g. Yoo).

1050-6411/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jelekin.2013.08.006 S.-y. Park, W.-g. Yoo / Journal of Electromyography and Kinesiology 23 (2013) 1350–1355 1351

Representative exercises for strengthening the latissimus dorsi 2.2. Instrumentation and inferior fibers of trapezius are pull down, pull ups, and rowing exercises. Among these, pull down exertion has been mostly A Trigno wireless system (Delsys, Boston, MA, USA) was used for investigated in kinematic and electromyography studies. Several obtaining electromyography (EMG) signals; the Trigno electrodes studies have demonstrated that muscle activation depends on grip (Delsys, Boston, MA, USA) was set as band pass of 20–450 Hz and width, expert instruction, and forearm orientation (Lusk et al., a common mode rejection ratio of 80 dB. The sensor 2010; Snyder and Leech, 2009; Signorile et al., 2002). Signorile (27 mm Â 37 mm Â 15 mm) included four skin contacts et al. (2002) have reported that wide grip hand position produces (5 Â 1 mm) made of pure silver (99.9%), which contain two pat- greater muscle activation than other hand positions. Lusk et al. ent-pending stabilizing references and distance between skin con- (2010) have recommended anterior pull down with pronated grip tacts is 1 cm. The EMG data were corrected with EMG-Works- for maximally activating the latissimus dorsi. In a recent study, pull Acquisition (Delsys) at 2000 Hz, which simultaneously showed data down was suggested as an exercise for independently activating the display. Two surface electrodes were placed on the following mus- inferior fibers of trapezius (Arlotta et al., 2011). The inferior fibers of cles of the right side: latissimus dorsi, 4 cm below the inferior tip trapezius and latissimus dorsi have similar obliquity of muscle’s of the scapula, half the distance between the spine and lateral edge pull, but the inferior fibers of trapezius could be activated with of the torso. The electrode was placed at an oblique angle of 25°; the high arm elevation angle because the most pronounced scapular and the inferior fibers of trapezius, at 1.5 cm lateral and oblique to motion occurs between 80 and 120 of arm elevation (Ebaugh et al., the T6 spinal process (Cram et al., 1998). Because there were differ- 2005; Bagg and Forrest, 1988). In addition, the inferior fibers of the ences between size of the participants, muscle belly of the latissi- trapezius are arranged within the frontal plane, while the arrange- mus dorsi and the inferior fibers trapeizus were identified with ment of the latissimus dorsi has components of both the sagittal the manual muscle testing (Kendall et al., 2005). To exclude any and frontal planes. However, there were no study investigated the influence of electrical noise, the skin was prepared for EMG mea- effect of movement planes and arm elevation angles of the pull surement by cleaning the electrode site with alcohol, and lightly down exertion on muscular activation, both of the inferior fibers abrading the skin with fine sandpaper. of trapezius and latissimus dorsi. Some previous studies have performed pull down as an isotonic 2.3. Exercise procedure exercise, which is the general form. However, difficulty remains in adjusting the exercise to patients who need rehabilitation exer- Prior to the pull-down exercises, maximal voluntary isometric cises at an early stage. It is considered that isometric exercise for contractions (MVCs) for each muscle were performed to normalize shoulder rehabilitation is a more stable way of initiating muscular the individual differences. The following EMG normalizing proce- activation without increasing load at the glenohumeral joint, espe- dure was suggested previously (Cram et al., 1998; Kendall et al., cially in patients with limitations in shoulder mobility (Ellenbecker 2005). A 5-s MVC was done for each muscle using three trials. and Cools, 2010; Millett et al., 2006). Although one previous study The first and last second of each trial was excluded and the mean has suggested activation of the shoulder muscle, including latissi- value of the middle 3 s was used for normalization. mus dorsi, under isometric conditions and various angles and Subjects performed three trials of pull down exercise for each of planes, there remains a lack of evidence about which shoulder an- nine conditions in randomized order: three planes (sagittal, scapu- gle and movement plane are effective for activating the latissimus lar, and frontal plane) Ã three shoulder angles (60°,90°, and 120°). dorsi and the inferior fibers of trapezius during the pull down exer- The load for pull down was not controlled, but determined as max- cise (Anders et al., 2004). This previous study did not statistically imal isometric exertion against a fixed pull down bar. From a compare the muscular difference according to shoulder angle and standing position, subjects grasped the bar as pronated and with movement plane but compared sex differences. a wide grip. Shoulder angle and planes for each condition were Therefore, the present study is to investigate the activation of determined by measuring with a goniometer and inclinometer, the latissimus dorsi and the inferior fibers of trapezius under con- and stacking wooden plates under the participant’s feet (Fig. 1). ditions of various shoulder angles (60°,90° and 120°), and three One researcher fixed the participant’s pelvis so as not to be rotated planes of movement (sagittal, scapular, and frontal plane) during or translated in an upward direction. Each isometric exertion was pull down exercise. The purpose was to find out effective means maintained for 5 s, and the middle 3 s were used for further anal- of isometric pull down exercise for activating the musculatures. ysis. Three seconds of EMG data during the pull down were aver- We hypothesized that the inferior fibers of the trapezius might aged, and the data were expressed as %MVC value against be activated with increased shoulder elevation angles and closer normalized data. The 5 s of isometric contraction was controlled proximity to the frontal plane, while the latissimus dorsi might by a 60-Hz metronome. Prior to measurement, each participant be activated with decreased shoulder elevation angles and closer was instructed verbally and visually about how to perform a pull proximity to the sagittal plane. down, and given a 5-min practice time for each condition for famil- iarization of exertion. Three minutes of rest time was given to each participant between trials and conditions. 2. Methods 2.4. Data analysis 2.1. Population PASW Statistics (version 18.0; SPSS, Chicago, IL, USA) was used This study was performed on 14 asymptomatic men aged 20– to analyze significant differences in the %MVC of each muscle. A 22 years (mean ± SD: 21.8 ± 1.4 years), whose height and weight two-way repeated measures analysis of variance was used to were 175.4 ± 5.2 cm and 68.1 ± 2.1 kg, respectively. Subjects with determine the effect of planes (frontal, scapular, and sagittal) and a history of upper extremity pain or discomfort in the past shoulder angles (60°,90°, and 120°) on the EMG data. Preliminary 6 months were excluded. For consistency, all subjects were right- analysis revealed there was no interaction between planes of exer- hand dominant, which the dominance was defined as the one used tion and shoulder angles. Specific pair-wise comparison between for writing. Ethical approval for this study was obtained from the conditions of shoulder angles and between those of planes were Inje University Faculty of Health Sciences Human Ethics Commit- done through Bonferroni correction, and a significant difference tee. The participants provided informed consent. was revealed (p = 0.05). 1352 S.-y. Park, W.-g. Yoo / Journal of Electromyography and Kinesiology 23 (2013) 1350–1355

Fig. 1. Measurements of the isometric pull down exercises in this study. (A) Exercise with 90° shoulder ﬂexion in sagittal plane. (B) Exercise with 60° shoulder abduction in frontal plane. (C) Goniometric measurement of the shoulder. (D) Exercise with 120° shoulder ﬂexion in scapular plane.

Table 1 Descriptive statics of normalized EMG and ratio values during isometric pull down exertions.

Plane Shoulder angles P-value

60° 90° 120° Plane Angles Latissimus dorsi (LD) Frontal plane 90.46 ± 34.77 72.44 ± 28.13 52.03 ± 18.83 Scaption plane 80 ± 40.74 66.53 ± 31.25 44.46 ± 14.76 0.154 0.001* Sagittal plane 78.68 ± 33.17 67.47 ± 32.89 45.20 ± 18.12 Inferior ﬁbers of trapezius (IT) Frontal plane 34.14 ± 18.88 46.77 ± 21.58 59.29 ± 17.58 Scaption plane 29.12 ± 19.13 40 ± 22.8 55.05 ± 23.81 0.226 0.000* Sagittal plane 36.68 ± 20.77 47.55 ± 20.44 57.41 ± 19.97 Ratio(LD/IT) Frontal plane 3.28 ± 1.87 1.79 ± 0.86 0.94 ± 0.47 Scaption plane 4.19 ± 3.95 2.03 ± 1.21 1 ± 0.73 0.107 0.000* Sagittal plane 2.6 ± 1.5 1.57 ± 0.85 0.84 ± 0.35

* Signiﬁcant difference between conditions.

3. Results comparison revealed that the normalized EMG of the latissimus dorsi was significantly (p < 0.05) higher within 120° shoulder ele- 3.1. Latissimus dorsi vation than 60° and 90° elevation (Fig. 3). The pull down within 90° of shoulder elevation also showed a significantly (p < 0.05) The average of normalized EMG values of the latissimus dorsi higher normalized EMG of the latissimus dorsi than pull down differed significantly (F2.12 = 12.674, p < 0.05) according to shoulder within 60° shoulder elevation (Fig. 3). There were no major effects angle (Table 1). The activity levels of the latissimus dorsi during (F2.12 = 1.687, p = 0.226) for planes of movement in latissimus dorsi pull down exertions are shown in Fig. 2. There was no interaction activation (Table 1). Interaction between planes of movement and

(F4.10 = 0.427, p = 0.786) between shoulder angles and planes of shoulder angles was not indentified (F4.10 = 0.320, p = 0.858). movement. The pull down within 60° and 90° shoulder elevation showed a significantly (p < 0.05) higher normalized EMG of the 3.3. Ratio between latissimus dorsi and inferior fibers of trapezius (LD/ latissimus dorsi than the same exertion within 120° (Fig. 2). IT ratio) However, there were no significant (F2.12 = 2.195, p = 0.154) difference between the conditions of the planes (Table 1). The ratios between the latissimus dorsi and inferior fibers of trapezius during isometric conditions are shown in Table 1. The LD/IT

3.2. Inferior fibers of trapezius ratio differed significantly (F2.12 = 19.86, p < 0.05) according to shoulder angle (Table 1). The LD/IT ratio was significantly The normalized EMGs of the inferior fibers of trapezius during (p < 0.05) higher for 60° shoulder elevation than for 90° and 120° isometric pull down conditions are shown in Table 1. There were shoulder elevation (Fig. 4). The pull down with 90° shoulder eleva- significant effects (F2.12 = 39.29, p < 0.05) for shoulder elevation an- tion also had a significantly (p < 0.05) higher LD/IT ratio than for pull gles in latissimus dorsi activation (Table 1). The result of pair-wise down with 120° shoulder elevation (Fig. 4). For LD/IT ratio, there S.-y. Park, W.-g. Yoo / Journal of Electromyography and Kinesiology 23 (2013) 1350–1355 1353

fered according to shoulder angle, which was significantly greater for a relatively lower elevation angle. Although we could not con- firm the causes, due to the absence of measuring three dimensional shoulder positions, the reduced active tension of the latissimus dorsi could have resulted from increased internal rotation of the shoulder, followed by arm elevation. Recent research has shown the kinematics of shoulder elevation, and has reported that the average amount of external rotation of the humerus was 14° from the starting position to 60°, but the humerus then rotated inter- nally by an average 9° by the time the shoulder reached maximum elevation (Matsuki et al., 2012). Another previous study has compared the normalized EMG of the latissimus dorsi during different types of exercise, and has reported that seated row exercise (performed with a low shoulder elevation angle) induces greater acti- Fig. 2. Comparison of normalized sEMG data (%MVC, mean ± SD) for the latissimus dorsi during isometric pull down exertions using pair-wise comparison. Ã Signifi- vation of the latissimus dorsi than other types of pull down cant difference between conditions. exercise (Lehman et al., 2004). Both the previous and present results indicate that a high level of shoulder elevation for pull down exercise is not required for activating the latissimus dorsi. In contrast to the latissimus dorsi, the mean normalized EMG in the inferior fibers of trapezius showed gradual increases with increases in shoulder elevation angle. Both the latissimus dorsi and inferior fibers of trapezius contribute to depression of the shoulder girdle, but the insertion was different that the inferior fibers of trapezius for the apex of the scapular spine, and latissimus dorsi for the intertubercular groove of humerus (Kendall et al., 2005). Re- cent findings have suggested that the most pronounced scapular upward rotation occurs in the mid-range (90–120°) of arm elevation (Ebaugh et al., 2005). Additionally, Bagg and Forrest (1988) have reported a mean glenohumeral to scapular rotation ratio of 3.29:1 below 90° of abduction, and 0.71–1 between 82° and 139° (Bagg and Forrest, 1988). In terms of the active length–tension relationship, production of muscular activation can be accomplished by adopting an appropriate position above the resting Fig. 3. Comparison of normalized sEMG data (%MVC, mean ± SD) for the inferior length. Although the length of the latissimus dorsi receded from fibers of trapezius during isometric pull down exertions using pair-wise compar- the appropriate length of exertion with increased shoulder eleva- ison. Ã Significant difference between conditions. tion angles, we estimated that the length of the inferior fibers of trapezius approached the appropriate length for exertion with increased scapular upward rotation. Another explanation for these contrast results between the latissimus dorsi and inferior fibers of trapezius is the difference in angle of pull of the muscles. A clinical literature demonstrated that the latissimus dorsi has lower obliquity of muscle’s pull for the humerus than do the inferior fibers of trapezius for the scap- ulae (Neumann et al, 2002). The greater the obliquity of the muscle’s attachment, the less the force of the muscle contraction contributes to the motion at the joint (Muscolino, 2011). Arwert et al. (1997) investigated the EMG of shoulder muscle relation to force direction, and demonstrated controversial direction of muscle’s force production between the latissimus dorsi and the inferior fibers of trapezius. We speculated that the inferior fibers of the trapezius and latissimus dorsi have close to appropriate leverage of a muscle at 120° and 60° of arm elevation, respectively. Fig. 4. Comparison of the latissimus dorsi/inferior fibers of trapezius ratio during isometric pull down exertions using pair-wise comparison. Ã Significant difference The ratios between the muscle groups have been suggested for between conditions. identifying relative and selective activation of target muscles during exercise (Park et al., 2013; Ludewig et al., 2004). With a similar pattern to normalized EMG of the latissimus dorsi, the ratios also were no interactions (F4.10 = 1.033, p = 0.437) between planes of differed significantly between angles of shoulder elevation. For movement and shoulder angles, as well as no significant difference 120° elevation during pull down exercise, the ratio was close to (F2.12 = 2.709, p = 0.107) between planes of movement (Table 1). 1, regardless of movement planes, which meant that the latissimus dorsi and the inferior fibers of the trapezius were activated at a 4. Discussion similar level. The 60° and 90° shoulder elevation conditions during pull down showed 2–4 times greater ratios than for 120° elevation, This study examined the influence of shoulder elevation angles which indicated that selective activation of the latissimus dorsi can and planes of exercise on muscular activation during isometric pull be accomplished with lower arm elevation during pull down down exertion. The normalized EMG of the latissimus dorsi dif- exertion. 1354 S.-y. Park, W.-g. Yoo / Journal of Electromyography and Kinesiology 23 (2013) 1350–1355

Although different pull down actions were applied in this study funded by the Ministry of Education, Science and Technology (e.g., pull down within the sagittal plane induced shoulder exten- (No. 2012R1A1B4001058). sion mainly, but frontal plane induced shoulder adduction), there were no significant differences in latissimus dorsi, inferior fibers of trapezius, and LD/IT ratio between the movement planes. The References changes in movement plane were demonstrated as changes in grip width of the pull down exertion. In agreement with previous find- Anders C, Bretschneider S, Bernsdorf A, Erler K, Schneider W. Activation of shoulder muscles in healthy men and women under isometric conditions. J Electromyogr ings, the movement plane (grip width in previous study) did not Kinesiol 2004;14(6):699–707. significantly influence the latissimus dorsi activation, nor was Arlotta M, Lovasco G, McLean L. Selective recruitment of the lower fibers of there any interaction between grip width and shoulder orientation trapezius muscle. J Electromyogr Kinesiol 2011;21(3):403–10. Arwert HJ, de Groot J, Van Woensel WW, Rozing PM. Electromyography of shoulder (Lusk et al., 2010). It was investigated that the three positions of muscles in relation to force direction. J Shoulder Elbow Surg 1997;6(4):360–70. pull down included front of neck (scapular plane), frontal plane Bagg SD, Forrest WJ. A biomechanical analysis of scapular rotation during arm using a V-shaped bar, and behind the neck (Sperandei et al., abduction in the scapular plane. Am J Phys Med Rehabil 1988;67(6):238–45. Cram JR, Kasman GS, Holtz J. Introduction to surface electromyography. 1st 2009). They also reported that there was no significant difference ed. Aspen; 1998. in normalized EMG of the latissimus dorsi between the types of Ebaugh DD, McClure PW, Karduna AR. Three-dimensional scapulothoracic motion pull down exertion. However, the previous and present results do during active and passive arm elevation. Clin Biomech (Bristol, Avon) 2005;20(7):700–9. not indicate that there is no necessity to consider movement Ellenbecker TS, Cools A. Rehabilitation of shoulder impingement syndrome and planes during pull down exercise. The glenohumeral ligament rotator cuff injuries: an evidence-based review. Br J Sports Med could be tightened with increases of shoulder horizontal abduc- 2010;44(5):319–27. tion. When the capsular ligament is over-tightened, it may increase Fraulin FO, Louie G, Zorrilla L, Tilley W. Functional evaluation of the shoulder following latissimus dorsi muscle transfer. Ann Plast Surg 1995 joint contact pressure and lead to soft tissue damage (Itoi et al., Oct;35(4):349–55. 1996). Although the mean normalized EMG of the latissimus dorsi Forthomme B, Heymans O, Jacquemin D, Klinkenberg S, Hoffmann S, et al. Shoulder was higher during pull down with the frontal plane than the scap- function after latissimus dorsi transfer in breast reconstruction. Clin Physiol Funct Imaging 2010;30(6):406–12. ular or sagittal plane, exertion with the frontal plane is not recom- Holmgren T, Björnsson Hallgren H, Öberg B, Adolfsson L, Johansson K. Effect of mended because of the risk of shoulder strain and absence of specific exercise strategy on need for surgery in patients with subacromial significant advantages for activating the latissimus dorsi or the impingement syndrome: randomised controlled study. BMJ 2012;20(344):787. Illyés A, Kiss RM. Electromyographic analysis in patients with multidirectional inferior fibers of the trapezius. shoulder instability during pull, forward punch, elevation and overhead throw. The present study had some limitations. First, we examined Knee Surg Sports Traumatol Arthrosc 2007;15(5):624–31. EMG data normalized relative to MVCs, but some cases showed Illyés A, Kiss RM. Kinematic and muscle activity characteristics of multidirectional shoulder joint instability during elevation. Knee Surg Sports Traumatol Arthrosc >100% of the MVC. A previous study demonstrated that the isomet- 2006;14(7):673–85. ric pull-down exertion is used to induce MVC of the latissimus dor- Itoi E, Hsu HC, An KN. Biomechanical investigation of the glenohumeral joint. J si (Snyder and Leech, 2009; Signorile et al., 2002). Further study is Shoulder Elbow Surg 1996;5(5):407–24. Kendall FP, McCreary EK, Provance PG, Rodgers MM, Romani WA. Muscles: testing needed to determine the proper MVC method for the latissimus and Function, with posture and pain. 5th ed. Baltimore, MD: Lippincott dorsi. Second, the electrode placement did not include the pecto- Williams & Wilkins; 2005. ralis major and biceps brachii, to focus on the activation of the Kiss RM, Illyés A, Kiss J. Physiotherapy vs. capsular shift and physiotherapy in latissimus dorsi and inferior fibers of the trapezius during isomeric multidirectional shoulder joint instability. J Electromyogr Kinesiol 2010;20(3):489–501. pull down exercise with two variables. Finally, there was a lack of Koh CE, Morrison WA. Functional impairment after latissimus dorsi flap. ANZ J Surg input with regard to controlling the movement of the humerus and 2009;79(1–2):42–7. forearm, such as internal and external rotation, due to the absence Lehman GJ, Buchan DD, Lundy A, Myers N, Nalborczyk A. Variations in muscle activation levels during traditional latissimus dorsi weight training exercises: of kinematic data. an experimental study. Dyn Med 2004;30:3. 1. Ludewig PM, Hoff MS, Osowski EE, Meschke SA, Rundquist PJ. Relative balance of serratus anterior and upper trapezius muscle activity during push-up exercises. 5. Conclusions Am J Sports Med 2004;32:484–93. Lusk SJ, Hale BD, Russell DM. Grip width and forearm orientation effects on muscle activity during the lat pull-down. J Strength Cond Res 2010;24(7):1895–900. The present study was performed to evaluate whether shoulder Marinko LN, Chacko JM, Dalton D, Chacko CC. The effectiveness of therapeutic elevation angle and plane of movement affected the latissimus exercise for painful shoulder conditions: a meta-analysis. J Shoulder Elbow Surg dorsi and inferior fibers of trapezius during isometric pull down 2011;20(8):1351–9. Matsuki K, Matsuki KO, Yamaguchi S, Ochiai N, Sasho T, Sugaya H, et al. Dynamic exercise. Activation of the latissimus dorsi was gradually decreased in vivo glenohumeral kinematics during scapular plane abduction in healthy with increases in arm elevation angle, but the inferior fibers of tra- shoulders. J Orthop Sports Phys Ther 2012;42(2):96–104. pezius activity showed the opposite pattern. In addition, we con- Millett PJ, Wilcox 3rd RB, O’Holleran JD, Warner JJ. Rehabilitation of the rotator cuff: firmed that the both the latissimus dorsi and inferior fibers of an evaluation-based approach. J Am Acad Orthop Surg 2006;14(11):599–609. Muscolino JE. Kinesiology: the skeletal system and muscle function. 2nd ed. St trapezius activities were not related to planes of movement. Dur- Louis: Mosby; 2011. p. 479–99. ing isomeric pull down for activating the latissimus dorsi, we rec- Neumann DA. Kinesiology of the musculoskeletal system: foundations for physical ommend that selective activation of the latissimus dorsi can be rehabilitation. St Louis: Mosby; 2002. Park KM, Cynn HS, Yi CH, Kwon OY. Effect of isometric horizontal abduction on accomplished with low shoulder elevation angle and selecting less pectoralis major and serratus anterior EMG activity during three exercises in horizontally abducted posture, to reduce risk of injury. subjects with scapular winging. J Electromyogr Kinesiol 2013 [Epub ahead of print]. Signorile JF, Zink AJ, Szwed SP. A comparative electromyographical investigation of Conflict of Interest muscle utilization patterns using various hand positions during the lat pull- down. J Strength Cond Res 2002;16(4):539–46. Snyder BJ, Leech JR. Voluntary increase in latissimus dorsi muscle activity during The authors declare that there are no conflicts of interest. the lat pull-down following expert instruction. J Strength Cond Res 2009;23(8):2204–9. Spear SL, Hess CL. A review of the biomechanical and functional changes in the Acknowledgments shoulder following transfer of the latissimus dorsi muscles. Plast Reconstr Surg 2005;115(7):2070–3. Sperandei S, Barros MA, Silveira-Júnior PC, Oliveira CG. Electromyographic analysis This research was supported by the Basic Science Research Pro- of three different types of lat pull-down. J Strength Cond Res gram through the National Research Foundation of Korea (NRF) 2009;23(7):2033–8. S.-y. Park, W.-g. Yoo / Journal of Electromyography and Kinesiology 23 (2013) 1350–1355 1355

Se-yeon Park received his master of science in physical Won-gyu Yoo received the Ph.D. in Physical Therapy therapy at the Inje university in 2012 and now is a Treatments for Musculoskeletal Disorders from the doctor of science student in physical therapy and Yonsei University, the Republic of Korea, in 2008. He rehabilitation sciences at Inje university. He is currently was the acting head of the Department of Physical working as a researcher of National Research Founda- Therapy at Inje University in Gimhea, Gyeongsangnam- tion of Korea and a member of the Korean Physical do, Republic of Korea. He is working as the main Therapy Association. His research interests include researcher of National Research Foundation of Korea for musculoskeletal response in physical therapy inter- posture correction research of computer users. His ventions, and scapular dyskinesis. research interests include biological signal processing, chronic muscle pain and dysfunction due to overuse, and medical device development for physical therapy interventions.