Comparison of upper and lower trapezius electromyographic activity during Y-raise exercise with and without isometric adduction in healthy volunteers

Abstract

BACKGROUND:

Lower trapezius (LT) plays an important role in maintaining the stability of the scapula. Sufficient activation of LT can reduce the risk of rotator cuff tear and shoulder impingement syndrome. The Y-raise exercise has been recommended for effective LT activation. However, the upper trapezius (UT) can be co-activated during universal Y-raise exercise.

OBJECTIVE:

This study aimed to compare the activity of the UT, LT, and serratus anterior (SA) during Y-raise exercise with and without isometric adduction (IAD) using Thera-Band.

METHODS:

21 healthy males voluntarily participated in the study. The participants were asked to perform Y-raise exercise with and without IAD using Thera-Band. Surface electromyography was used to measure the muscle activity of UT, LT, and SA during Y-raise exercise with and without IAD. Paired t-test was used to analyze the significance of the muscle activity of UT, LT, and SA as well as the activity ratio of LT/UT and LT/SA. The significance level was set at $\alpha=$ 0.05.

RESULTS:

Compared with Y-raise exercise without IAD, the muscle activity of UT and SA decreased ( $p=$ 0.001 and $p=$ 0.003, respectively), whereas that of LT increased ( $p=$ 0.038) during Y-raise exercise with IAD. Additionally, the activity ratio of LT/UT and LT/SA was greater during Y-raise exercise with IAD ( $p=$ 0.001 and $p=$ 0.001, respectively).

CONCLUSION:

Y-raise exercise with IAD using Thera-Band is recommended as an efficient exercise to selectively activate the LT and increase the activity ratio of LT/UT and LT/SA.

Keywords

Lower trapezius reciprocal inhibition upper trapezius Y-raise exercise

1. Introduction

The shoulder joint is composed of complex structures of the glenohumeral joint. It is the most mobile joint among the synovial joints in the human body [1]. The shoulder joint is involved not only in sagittal (flexion and extension), frontal (adduction and abduction), and transverse (internal and external rotations, horizontal adduction, and horizontal abduction) plane motion but also in circumduction [1]. The joint structure consists of the head of the humerus and the glenoid fossa of the scapula [1]. The glenoid fossa is relatively smaller than the humerus head, indicating that joint stability is conferred by several structures [1]. During shoulder motion, the glenoid labrum, joint capsule, coracohumeral arch, and glenohumeral ligament of the scapula act as static stabilizers [2], whereas the rotator cuff and surrounding muscles (trapezius, rhomboids, and serratus anterior [SA]) act as dynamic stabilizers. Other structures such as ligaments, tendons, and connective tissues connect the humerus and scapula to maintain joint stability and contribute to the functional movement of the shoulder joint [3]. Weakness of the stabilizing soft tissues of the shoulder joint causes several shoulder problems [4, 5]. Scapular winging can be caused by weakness of the SA and impairment of the long thoracic nerve [6, 7]. The humerus anterior glide type can occur due to weakness and lengthening of the shoulder internal rotation muscle such as subscapularis due to shortness and dominance recruitment pattern of the pectoralis major (PM) [4, 5]. Weakness of the lower trapezius (LT) decreases the posterior tilt (PT) of the scapula, leading to shoulder joint dysfunction and shoulder impingement syndrome (SIS) [8].

The trapezius consists of upper, middle, and lower fibers, which play important roles in maintaining stability and functional movement [9, 10]. Lateral and upward rotations and PT of the scapula were required for scapulohumeral rhythm during arm elevation [11]. The scapulohumeral rhythm is generated by the coordinated activation of the upper trapezius (UT), middle trapezius, and LT. In particular, UT and LT generate scapula movement through a combined force with SA. Among them, the UT plays a crucial role in the kinematics of the shoulder joint by generating elevation and upward rotations of the scapula [1]. However, synergistic muscle imbalance of the scapular motion can be caused by excessive use of UT and inhibition of LT activity. Excessive use of UT may lead to muscle dominance related to increased muscle activity and possible muscle shortness [4, 12]. In contrast, inhibition of LT may cause muscle weakness due to insufficient muscle activity [13, 14]. The UT and LT can be influenced by each other on counter-balance force because both muscles are superiorly and inferiorly attached to the scapula, respectively [1]. Although both UT and LT play important roles as muscle synergists in generating the scapular upward rotation [1], the LT can be lengthened during scapula elevation with activation of UT [13]. It could alter the length–tension relationship and cause faulty movement patterns of the scapulohumeral rhythm [1, 4]. Furthermore, pain and tenderness in the UT due to increased tension can cause chronic neck and shoulder pain [15]. A myofascial trigger point may cause muscle tenderness in the UT, which may affect the strength of the shoulder joint [16]. LT plays an important role in maintaining the stability of the scapulothoracic joint and can assist in performing accurate axial rotation of the humerus [17]. In addition, LT contributes to the PT of the scapula to maintain a sufficient subacromial distance during full flexion and abduction. This motion can reduce the risk of rotator cuff tear and SIS [18]. A previous study compared UT and LT activity during arm raise exercise in patients with SIS and healthy individuals [17]. Compared with the healthy group, the UT activity increased by 21%, whereas the LT activity decreased by 14% in the SIS group [17]. Another previous systematic study investigated the scapulothoracic muscle activity between SIS and healthy groups [19]. Compared with the healthy group, excessive UT activity was reported during abduction in the SIS group in previous studies [8, 17, 20]. However, the LT activity was lower in the SIS group than in the healthy groups in previous studies [17, 20, 21]. Weakness of the LT can result in changes in faulty movement patterns such as reduced lateral and upward rotations and PT of the scapula [22, 23]. A previous study reported not only decreased internal rotation and abduction range of motion but also reduced internal rotation strength in assembly workers with SIS compared with those in the healthy group [24]. Therefore, sufficient LT activity is necessary to help prevent shoulder problems such as rotator cuff tears, SIS, and faulty movement patterns [18, 19].

Several exercises have been recommended for effective LT activation [25]. Among them, arm-lifting with shoulder abduction has been used to activate the LT in several studies [25, 26, 27, 28]. A previous study compared LT activity during arm-lifting based on shoulder abduction angles (180^∘, 160^∘, 125^∘, 90^∘, and 75^∘). The greatest LT activity was observed during 160^∘ abduction of the shoulder joint [26]. Another previous study reported that the LT activity was greater during arm-lifting with 145^∘ abduction than during that with 180^∘ abduction [27]. LT showed improved muscle activity during arm-lifting, with the arm diagonally in line with the muscle fibers [25, 26, 27, 28]. These exercises are known as Y-raise exercises as they are performed in a Y shape. However, although the universal Y-raise exercise can effectively activate the LT, the UT can be evoked with muscle co-activation. Therefore, this type of universal Y-raise exercise should be limited to selectively activating the LT [25]. In a previous study where the Y-raise exercise was performed, the average muscle activation level (%maximal voluntary isometric contraction; %MVIC) in the LT was 97%, indicating the highest activation level among other exercises [25]. However, UT also exhibited a relatively high activation level of 79% [25]. This result revealed an activity ratio of LT/UT of approximately 1.22 [25]. Additionally, a previous study investigated the effect of scapular PT exercise after pectoralis minor (Pm) stretching on the activity of scapular upward rotators (UT, LT, SA) during Y-raise exercise in patients with shortened Pm [29]. When scapular PT exercises were performed after Pm stretching, the scapular upward rotation angle increased, along with an increase in the activity of scapular upward rotators [29]. A previous study reported that the muscle activity levels of UT and LT were 41% and 69%, respectively, indicating an activity ratio of LT/UT of 1.40 [29]. Despite the application of the two exercises (scapular PT exercise after Pm stretching), a selective LT exercise could be limited because of UT muscle co-activation [29]. Therefore, UT activity inhibition is necessary to perform Y-raise exercise for the selective activation of the LT.

Reciprocal inhibition can prevent unnecessary muscle activation through the contraction of agonist muscles [30]. Although UT activity can be increased through the elevation and upward rotation of the scapula during shoulder abduction [1], it can be inhibited by the depression and downward rotation of the scapula during shoulder adduction [1]. Therefore, isometric adduction (IAD) can be adopted to effectively reduce UT activation during LT activation exercise. A previous study investigated the effects of isometric horizontal abduction (IHA) on the activity of SA and PM during SA activation exercise in a patient with scapular winging [31]. The activity of PM decreased, whereas that of SA increased while performing exercise with IHA using Thera-Band [31]. Therefore, unnecessary muscle activation can be reduced by reciprocal inhibition during exercise [31]. Furthermore, it is possible to maintain the selective muscle activity ratio by increasing the activity of the target muscle with reciprocal inhibition [31].

Many previous studies have confirmed the effects of shoulder abduction angle and arm rotation position on UT and LT activity during Y-raise exercise [26, 28]. However, no studies have investigated the effect of IAD on UT, LT, and SA activity during Y-raise exercise using Thera-Band to date. This study aimed to determine whether Y-raise exercise with or without IAD using Thera-Band can selectively increase the activity of LT. It also aimed to measure the activity ratios of LT/UT and LT/SA. We hypothesized that the muscle activity of LT and activity ratio of LT/UT and LT/SA show a greater increase during Y-raise exercise with IAD using Thera-Band.

2. Methods

2.1 Participants

In this pilot study involving five patients, G*Power (ver. 3.1.2; Franz Faul, University of Kiel, Kiel, Germany) was used to compare LT activation between Y-raise exercises with and without IAD. The software setting was as follows: power, 0.95; $\alpha$ -level, 0.05; and effect size, 1.33. Sample analysis revealed that at least eight participants were required in this study. A total of 21 healthy men (age, 22.86 $\pm$ 1.74 years; height, 175.58 $\pm$ 3.84 cm; and weight, 74.08 $\pm$ 11.90 kg) who showed negative results in scapular instability tests, such as eccentric lowering, shoulder flexion, and shoulder internal rotation tests, were included in this study [4, 5]. The exclusion criteria were a history of shoulder surgery, pain due to neurological or musculoskeletal problems within 6 months, and inability to perform a full range of motion of the shoulder joint. This study was approved by the Institutional Review Board of Hoseo University [1041231-230816-HR-165]. Written informed consent was obtained from all participants.

Figure 1.

Y-raise exercise with isometric adduction using Thera-Band (A, B) and without isometric adduction using Thera-Band (C, D).

2.2 Electromyography (EMG) and data processing

The surface EMG system (Ultium EMG system, Noraxon, USA) was used to measure UT, LT, and SA activity. The EMG signal was sampled and amplified at 1,024 Hz with bandpass filtering of 10–450 Hz. The notch filter was set at 60 Hz, and the surface EMG data were evaluated using the root mean square method with 50 ms data point of moving window [27]. Ag/AgCl electrode was attached to the muscle after shaving and cleaning the electrode region with alcohol cottons. The UT electrode was attached parallelly to the direction of the muscle fiber in the middle part between the spine and the lateral acromion on the muscle belly [32]. The LT electrode was diagonally attached to the oblique muscle at the inferomedial border of the scapula, approximately 5 cm below the spine of the scapula [32]. The SA electrode was placed on the medial side of the latissimus dorsi at the portion of the interior of the scapula below the axillary region [32]. The electrode location was determined according to the method described in previous studies [27, 28, 31]. Muscle activity was assessed based on the dominant arm of the participants, and the first and last 1 s of the signal were discarded [33].

The MVIC was measured to normalize the three muscles (UT, LT, and SA) according to the guidelines mentioned in the previous literature [34, 35]. The MVIC of the UT was measured during shoulder elevation and neck extension when the participant performed neck rotation in the contralateral direction of the dominant muscle in the sitting position. The examiner induced resistance toward the anterolateral flexion of the head and depression resistance for the shoulder [34, 35]. The MVIC of the LT was measured during arm-lifting with scapular adduction and depression when the participant performed shoulder abduction in the direction of the muscle fiber diagonally in the prone position. The examiner induced resistance toward the downward direction of the arm [34, 35]. The MVIC of the SA was measured during scapular abduction when the participant was asked to perform approximately 90^∘ flexion of the shoulder in the supine position. The examiner grabbed the participant’s fist and pushed it proximally to induce resistance [34, 35]. For each participant, the MVIC was measured for 5 s, with a rest period of 1 minute between trials.

Table 1
Comparison of muscle activity during Y-raise exercise with and without isometric adduction ( $n=$ 21)

% MVIC	Conditions		Mean difference	CI (95%)		$t$	$p$	Effect size
	Without IAD	With IAD		Lower bound	Upper bound
UT	44.43 $\pm$ 17.93	23.64 $\pm$ 12.24	20.79	15.03	26.55	7.52	0.001	1.12
LT	45.62 $\pm$ 9.82	49.50 $\pm$ 12.12	$-$ 3.88	$-$ 7.53	$-$ 0.23	$-$ 2.21	0.038	0.35
SA	41.00 $\pm$ 15.81	29.94 $\pm$ 16.03	11.06	4.30	17.82	3.41	0.003	0.66

Mean $\pm$ standard deviation. MVIC, maximal voluntary isometric contraction; CI, confidence interval; UT, upper trapezius; LT, lower trapezius; SA, serratus anterior; IAD, isometric adduction.

Table 2

Comparison of activity ratio during Y-raise exercise with and without isometric adduction ( $n=$ 21)

Ratios	Conditions		Mean difference	CI (95%)		$t$	$p$	Effect size
	Without IAD	With IAD		Lower bound	Upper bound
LT/UT	1.19 $\pm$ 0.53	2.78 $\pm$ 2.09	$-$ 1.59	$-$ 2.47	$-$ 0.71	$-$ 3.77	0.001	0.49
LT/SA	1.28 $\pm$ 0.55	2.17 $\pm$ 1.34	$-$ 0.90	$-$ 1.36	$-$ 0.44	$-$ 4.06	0.001	0.81

Mean $\pm$ standard deviation. MVIC, maximal voluntary isometric contraction; CI, confidence interval; UT, upper trapezius; LT, lower trapezius; SA, serratus anterior; IAD, isometric adduction.

2.3 Procedures

The examiner informed the participants regarding the appropriate exercise posture. The participants familiarized themselves with the exercise for approximately 20 min. During the measurement, each participant performed three trials of each exercise with a 1 minute rest period between trials [31]. The order of the exercises was randomized using a random number generator program in Microsoft Excel (Microsoft Corp., Redmond, WA, USA). If the participant failed to maintain the accurate exercise posture during the trials, the obtained data were excluded from the analysis. The mean values of the results obtained from the three trials were used for data analysis. To avoid muscle fatigue, a 10-min resting period was provided between the conditions (with and without IAD) [31, 36]. The effects of the exercises were blinded to minimize the bias.

Resistance of IAD was applied using Thera-Band during exercise. The Thera-Band was placed on both wrists. The tensional load of the Thera-Band was considered when the participant could perform $>$ 10 reps while maintaining a consistent metronome speed [31, 37].

2.3.1 Y-raise exercise with and without Thera-Band

The angle of the shoulder was controlled using an angle plate. The angle plate could be set up with shoulder abduction angles of 90^∘–180^∘ by marking each 10^∘ with the acromion as the axis. The participants were asked to perform the Y-raise exercise at a 160^∘ abduction angle of the shoulder joint in the prone position because a previous study reported that LT was effectively activated during 160^∘ abduction of the shoulder joint [26]. The participant’s shoulder flexion at 180^∘ was measured using a goniometer, and a height-adjustable target bar was set at the corresponding position. To prevent limitation of the shoulder flexion by anatomical factors, the shoulder joint was laterally rotated [1]. When the participants performed Y-raise without IAD, their shoulder joint was abducted at 180^∘. Subsequently, the participant lifted up their arm to the target bar and performed shoulder abduction at 160^∘ (Fig. 1C, D). The angle of shoulder abduction was assessed by the examiner. The participants performed a Y-raise exercise with IAD, and Thera-Band was placed on both wrists (Fig. 1A, B) [31]. Tension force was not induced at the shoulder abduction angle of 180^∘, but appropriate tension was generated during IAD [37]. The same exercise procedure was followed for the Y-raise exercise without IAD (Fig. 1A, B). The participants maintained the touch of the target bar for 5-s under all conditions.

2.4 Statistical analysis

The data were analyzed using IBM SPSS Statistics version 20.0 (IBM Corp., Armonk, NY). The Shapiro–Wilk test was performed to analyze normally distributed data ( $p>$ 0.05). To assess the effects of IAD, the effect size was calculated using Cohen’s d. Values $>$ 0.8 were rated as strong, values $>$ 0.4 to $\leqslant$ 0.8 were considered as moderate, and values $\leqslant$ 0.4 were regarded as weak [38]. The muscle activity of UT, LT, and SA and the activity ratio of LT/UT and LT/SA were compared using paired t-test. Statistical significance was set at $\alpha=$ 0.05.

3. Results

A difference in muscle activity of the UT, LT, and SA, as well as the activity ratios of LT/UT and LT/SA between the Y-raise exercise with and without IAD were observed ( $p=$ 0.001, $p=$ 0.038, $p=$ 0.003, $p=$ 0.001 and $p=$ 0.001, respectively) (Tables 1, 2).

4. Discussion

The present study aimed to compare the muscle activity of UT, LT, and SA during Y-raise exercise with and without IAD. We hypothesized that the muscle activity of LT as well as the activity ratio of LT/UT and LT/SA increase during Y-raise exercise with IAD. The activity levels of UT, LT, and SA were initially 44%, 45%, and 41% during Y-raise exercise without IAD; however, those activity levels changed to 23%, 49%, and 29%, respectively, during exercise with IAD. The activity ratio of LT/UT and LT/SA was 1.19 and 1.28 during the Y-raise exercise without IAD, which increased to 2.78 and 2.17 during the Y-raise exercise with IAD, respectively. This finding indicates an increase in the muscle activity and activity ratio during Y-raise exercise with IAD compared with that during Y-raise exercise without IAD.

The muscle activity of UT and SA decreased during Y-raise exercise with IAD. This result can be considered as the effect of the reciprocal inhibition mechanism. This mechanism is induced by afferent impulses originating from the muscle spindle of the agonist muscle, stimulating inhibitory interneurons within the spinal cord [31, 39, 40]. This leads to the inhibition of alpha motor neurons responsible for the activity of the antagonist muscle [39, 40]. Therefore, the resistance provided to the agonist muscle (shoulder adductor) through IAD induced an inhibitory response in the antagonist muscle (UT and SA). The activity level of SA (%RVC; reference voluntary contraction) was initially 47% during the SA activation exercise without IHA. However, it increased to 55% during exercise with IHA. The muscle activity increased by 17% between the two conditions [31]. The activity levels of PM (%RVC) were 35% and 97% during forward flexion and wall push-up plus exercise without IHA, respectively [31]. Further, the activity levels of PM were approximately 30% and 52% during forward flexion and wall push-up plus exercises with IHA, respectively. These results indicated a reduction in the activity of PM by 14% and 46% during exercises with and without IHA, respectively [31]. The activity ratio of PM/SA was 0.7 and 1.3 during forward flexion exercise with and without IHA and 1.1 and 2.3 during wall push-up plus exercise with and without IHA, respectively [31]. The results of a previous study indicated that activation of the horizontal abductor (posterior deltoid, supraspinatus, infraspinatus, and teres minor) inhibited the activity of the antagonist muscle (PM) through IHA using Thera-Band [31]. It is limited to directly compare the results of previous and present studies. This is because the previous study measured the activity of SA and PM based on %RVC during SA activation exercise (forward flexion and wall push-up plus) [31]. Based on the reciprocal inhibition mechanism, induction of agonist muscle contraction affected the inhibition of the antagonist muscle activity; thus, our study may be similar to the previous study [31]. Therefore, the muscle activity of UT and SA may be effectively inhibited when performing Y-raise exercise with IAD using Thera-Band.

According to a previous study confirming the recruitment patterns and latencies of scapular upward rotators, such as UT, LT, and SA during abduction of the shoulder joint, the recruitment patterns were initiated by the UT, followed by the SA, and finally the LT [41]. Also, these muscles were confirmed to exhibit moderate activity at shoulder abduction angles of $>$ 150^∘ [1]. The activity of the three muscles was evenly measured at a moderate level during the Y-raise exercise without IAD; this is because the Y-raise exercise was performed at a shoulder abduction angle of 160^∘ in this study. However, the muscle activity of UT and SA may have been inhibited by the reciprocal inhibition mechanism during Y-raise exercise with IAD. In contrast, the activity of LT increased. Synergistic muscles can enhance shoulder joint performance by mutually influencing each other while working together to perform movements [42, 43]. In particular, when performing a movement with the same range of motion, if the activity of one muscle decreases, the activity of adjacent muscles increases, enabling the execution of the respective movement [31, 44, 45]. In the present study, the activity of scapular upward rotators (UT and SA) decreased during Y-raise exercise with IAD using Thera-Band. Thus, to perform the same movement, the activity of LT was relatively increased, consequently, the primary muscle involved in the upward rotation of the scapula may have shown a greater contribution to Y-raise exercise performance. In another study, due to shoulder flexion at 180^∘ in the end position of the Y-raise exercise, the LT may have acted as a muscle that not only contributes to the scapular upward rotation but also generates PT [1]. Although the muscle activity of UT and SA was inhibited by IAD, the LT activity may have increased as the PT of the scapula was maintained at the end position of the Y-raise exercise.

The Y-raise exercise has been widely recommended to effectively activate the LT [25, 26, 27, 28]. However, a previous study reported that the activity levels of LT and UT during Y-raise exercise were 97% and 79%, respectively [25]. Accordingly, the activity ratio of LT/UT was calculated as 1.22 [25]. In our study, the activity levels of LT and UT during Y-raise exercise without IAD were 45% and 44%, respectively. Accordingly, the activity ratio of LT/UT was 1.19, which was similar to that reported in previous studies [25]. Furthermore, the activity levels of LT and UT during the Y-raise exercise with IAD were 49% and 23%, respectively, and the activity ratio of LT/UT was calculated as approximately 2.78. Thus, the activity ratio of LT/UT increased during the Y-raise exercise with IAD compared with that during the Y-raise exercise without IAD. The SA can be activated via upward rotation and protraction of the scapula [1]. During the Y-raise exercise with and without IAD, the SA activity levels were 29% and 41% and the activity ratio of the LT/SA was 2.17 and 1.28, respectively. SA is an important muscle that provides stability to the scapula and trunk [1, 30, 46]. However, efficient activation of the SA has been reported during exercises with scapular protraction or weight-bearing through the arms [47], contrary to the exercise method used in this study. Therefore, Y-raise exercise with IAD may be recommended to selectively increase the activity of the LT, which is a scapular upward rotator.

Selective activation of the target muscle is important in the early-stage of rehabilitation [48]. Moreover, it is necessary to inhibit the surrounding synergistic muscles for increasing the activation of the specific muscles with weakness [4], as compensatory dominance of synergist muscles can lead to weakness in the agonist muscle [4, 48]. Muscle balance among the UT, LT, and SA is essential for achieving sufficient upward rotation of the scapular without compensations [1]. Therefore, the selective activity of LT should be accompanied by the controlled inhibition of UT [1, 4]. After selective muscle strengthening of LT is performed, upward rotation of the scapula should be functionally accompanied with sufficient muscle activation of LT as well as the UT and SA in the late-stage of rehabilitation.

Our study has several limitations. Measuring the standardized force of participants using an isokinetic dynamometer during the exercises was not possible due to experimental limitations. Activation of the agonist muscle (shoulder adductor) was not measured during the Y-raise exercise with IAD. Therefore, further study is needed to confirm the activation of the agonist muscle during exercises. The EMG data were obtained during the static contraction phase in the present study. The activity changes in UT, LT, and SA during dynamic contraction (abduction and adduction) with IAD should be further investigated in the future. The time epoch of EMG measurement was used only 50 ms in this study. Further study is needed to confirm rigorous analysis of changes in muscle activity and activation patterns during exercise, based on different time epoch setting such as 100 ms, 200 ms, and 300 ms. The strength of the shoulder adductor was not measured during the Y-raise exercise using Thera-Band. Thus, future studies need to determine the percentage of maximal strength that can be indicated for inducing selective LT activity during Y-raise exercise with IAD.

5. Conclusions

The Y-raise exercise with IAD using Thera-Band can be recommended for selectively increasing the LT activity while reciprocally inhibiting the UT and SA activities. The Y-raise exercise with IAD may be preferred in early-stage shoulder rehabilitation due to less muscle activity of UT and SA relative to LT muscle.

Author contributions

CONCEPTION: Jeon IC.

PERFORMANCE OF WORK: Hwang BH, Jeon IC.

INTERPRETATION OR ANALYSIS OF DATA: Hwang BH, Jeon IC.

PREPARATION OF THE MANUSCRIPT: Hwang BH, Jeon IC.

SUPERVISION: Jeon IC.

Ethical considerations

This study was approved by the Institutional Review Board of Hoseo University [1041231-230816-HR-165].

Funding

The authors report no funding.

Footnotes

Acknowledgments

The authors express their gratitude to all participants for their valuable time and dedicated participation in the present study.

Conflict of interest

The authors have no conflicts of interest to report.

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Comparison of upper and lower trapezius electromyographic activity during Y-raise exercise with and without isometric adduction in healthy volunteers

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSION:

Keywords

1. Introduction

2. Methods

2.1 Participants

Table 1 Comparison of muscle activity during Y-raise exercise with and without isometric adduction ( n = 21)

2.3.1 Y-raise exercise with and without Thera-Band

2.4 Statistical analysis

3. Results

4. Discussion

5. Conclusions

Author contributions

Ethical considerations

Funding

Footnotes

Acknowledgments

Conflict of interest

References

Table 1
Comparison of muscle activity during Y-raise exercise with and without isometric adduction ( $n=$ 21)